Add SSH remote backup support, new commands, and test suite

  - Add remote mode for SSH-based backups to servers like TrueNAS
  - Add SSH_IDENTITY_FILE config for non-root SSH keys
  - Add new commands: backup, status, list, dryrun
  - Add dependency checks for rsync, ssh, flock
  - Add timestamped logging
  - Fix: duplicate cron jobs on repeated setup
  - Fix: use mktemp for temp files
  - Fix: use portable sed instead of grep -oP
  - Fix: strengthen input validation with regex anchors
  - Fix: handle paths with spaces (newline-separated includes)
  - Change license from MIT to GPL v3
  - Add automated test suite (25 tests)
  - Update README with new features and testing docs

11 files changed, 2925 insertions, 285 deletions

diff --git a/LICENSE b/LICENSE
index 405b842..f288702 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,21 +1,674 @@
-MIT License
-
-Copyright (c) 2020 Craig Jennings
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+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.
diff --git a/README.org b/README.org
index 475280a..a9c012c 100644
--- a/README.org
+++ b/README.org
@@ -1,73 +1,215 @@
-* About rsyncshot
-Linux backups backup with bash, cron, rsync, and hard links. 
-Inspired by http://www.mikerubel.org/computers/rsync_snapshots/
-* Usage
-** Simple Setup
-rsyncshot installs itself. To setup, just run the following commands: 
+#+TITLE: rsyncshot
+#+AUTHOR: Craig Jennings
+
+* About
+
+rsyncshot creates space-efficient backups using rsync and hard links. Each snapshot looks like a full backup, but unchanged files share disk space across all snapshots.
+
+Supports backing up to local drives (USB, NFS) or remote servers via SSH.
+
+Inspired by [[http://www.mikerubel.org/computers/rsync_snapshots/][Mike Rubel's rsync snapshots]].
+
+* Quick Start
+
 #+begin_src sh
-  wget https://raw.githubusercontent.com/cjennings/rsyncshot/main/rsyncshot
-  sudo bash ./rsyncshot setup
+# Download and install
+wget https://raw.githubusercontent.com/cjennings/rsyncshot/main/rsyncshot
+sudo bash ./rsyncshot setup
+
+# Or clone and install
+git clone https://github.com/cjennings/rsyncshot
+cd rsyncshot && sudo make install
 #+end_src
-or simply clone this repo and run make install as root.
-** Automatic Hourly/Daily/Weekly Schedule via Cron
-rsyncshot will install a default schedule: 
-- every hour at the top of the hour
-- every day at noon
-- every week on Sunday at noon
-
-Edit the schedule with: 
+
+After setup, edit =/etc/rsyncshot/config= to set your backup destination.
+
+* Commands
+
+| Command                    | Description                              |
+|----------------------------+------------------------------------------|
+| =rsyncshot backup=         | Run an immediate one-off backup          |
+| =rsyncshot <name> <count>= | Create snapshot with name and retention  |
+| =rsyncshot setup=          | Install script and configure cron jobs   |
+| =rsyncshot status=         | Show installation and environment status |
+| =rsyncshot list=           | Show existing snapshots with sizes       |
+| =rsyncshot dryrun <n> <c>= | Preview backup without making changes    |
+| =rsyncshot help=           | Show help message                        |
+
+** Examples
+
 #+begin_src sh
-sudo crontab -e 
+# Immediate backup (creates manual.0)
+sudo rsyncshot backup
+
+# Keep 24 hourly snapshots
+sudo rsyncshot hourly 24
+
+# Keep 7 daily snapshots
+sudo rsyncshot daily 7
+
+# Preview what would be backed up
+sudo rsyncshot dryrun manual 1
+
+# Check if everything is configured correctly
+sudo rsyncshot status
+
+# See existing snapshots
+sudo rsyncshot list
 #+end_src
-** Manual Backups
-Manual backups in the terminal with two arguments: 
-- TYPE is a way to group backups together. Automatic backups will have the TYPE as HOURLY, DAILY, or WEEKLY. But you can give your manual backups any TYPE you wish. 
-- MAX is the maximum number of backups before the oldest gets removed. 
 
-For instance: 
+* Configuration
+
+All settings live in =/etc/rsyncshot/config=. Created automatically by =rsyncshot setup=.
+
+** Backup Modes
+
+*** Remote Mode (SSH)
+
+Back up to a remote server over SSH:
+
+#+begin_src sh
+REMOTE_HOST="myserver"
+REMOTE_PATH="/mnt/backups"
+#+end_src
+
+Backups go to =myserver:/mnt/backups/hostname/=.
+
+If your SSH key isn't in root's =~/.ssh/=, specify the path:
+
 #+begin_src sh
-rsyncshot manual 100
+SSH_IDENTITY_FILE="/home/youruser/.ssh/id_ed25519"
 #+end_src
 
-** Filtering
-Specify which directories to backup by editing /etc/rsyncshot/includes.txt. The defaults are:
+*** Local Mode
+
+Back up to a mounted drive (USB, NFS, etc.):
+
+#+begin_src sh
+REMOTE_HOST=""
+MOUNTDIR="/media/backup"
+#+end_src
+
+Backups go to =/media/backup/hostname/=. If the drive isn't mounted, rsyncshot will try to mount it.
+
+** What Gets Backed Up
+
+Edit =/etc/rsyncshot/include.txt= - one directory per line (supports paths with spaces):
+
 #+begin_src
-  - /home
-  - /etc 
-  - /usr/local/bin
+/home
+/etc
+/usr/local/bin
+# Comments start with #
 #+end_src
-Specify what filetype patterns to exclude by editing /etc/rsyncshot/excludes.txt. The defaults are:
+
+** What Gets Excluded
+
+Edit =/etc/rsyncshot/exclude.txt= - one pattern per line:
+
 #+begin_src
-  - *.pyc
-  - *.pyo
-  - *.class
-  - *.elc
-  - *.o
-  - *.tmp
-  - .cache*
+# Caches and temp files
+.cache
+*.tmp
+*.log
+
+# Build artifacts
+node_modules
+__pycache__
+*.pyc
 #+end_src
-** A Few Safeguards
-- rsyncshot separates backups by the machine's name. Use one external drive to backup multiple machines without conflicts.
-- rsyncshot leverages lockfiles to prevent overapping runs. A rsyncshot backup will not begin if a previous run is still in progress. 
-- rsyncshot will validate the specified source directories exist before beginning the backup. 
-- rsyncshot validates it's backing up to a mounted drive. If the drive isn't mounted, rsyncshot attempts to mount it. 
-- Backup directory permissions are changed to read-only to avoid mistaken deletion.
-- rsyncshot logs the details of all runs to /var/log/rsyncshot.log. 
-** Requirements
-- Bash
-- Cron
-- Rsync
-- Grep
-- Flock
-** Uninstalling
-- run 'sudo make uninstall' from the cloned directory.
-- delete relevant cron entries as root
-
-or become root and remove
-- the /usr/local/bin/rsyncshot script
-- the /etc/rsyncshot directory
-- (optional) /var/log/rsyncshot.log
-... and the relevant cron entries with crontab -e
-
-* Notes
-rsyncshot isn't production software, even though the underlying utilities are.
+
+* Automatic Backups
+
+Setup installs a default cron schedule:
+
+| Type   | Schedule                    | Retention |
+|--------+-----------------------------+-----------|
+| Hourly | Every hour, 1am-11pm        | 22        |
+| Daily  | Noon, Monday-Saturday       | 6         |
+| Weekly | Noon, Sunday                | 51        |
+
+Edit with =sudo crontab -e=.
+
+* How It Works
+
+1. rsync copies your directories to =destination/latest/=
+2. Oldest snapshot beyond retention count is deleted
+3. Existing snapshots rotate (=hourly.0= → =hourly.1= → =hourly.2=...)
+4. =latest/= is hard-linked to =hourly.0= (or whatever type you specified)
+
+Hard links mean unchanged files share disk space. A 100GB backup with 24 hourly snapshots might only use 110GB total if most files don't change.
+
+* Safeguards
+
+- *Separate by hostname* - one drive can back up multiple machines
+- *Lockfile* - prevents overlapping runs
+- *Validates sources* - checks directories exist before starting
+- *Validates destination* - checks mount or SSH connectivity
+- *Checks rsync exit code* - won't rotate if backup failed
+- *Read-only snapshots* - prevents accidental deletion
+- *Timestamped logging* - all runs logged to =/var/log/rsyncshot.log=
+
+* Requirements
+
+- bash
+- rsync
+- cron
+- grep
+- flock
+- ssh (for remote mode)
+
+The script checks for rsync and ssh at startup and shows install instructions if missing.
+
+* Uninstalling
+
+#+begin_src sh
+# If you cloned the repo
+sudo make uninstall
+
+# Or manually
+sudo rm /usr/local/bin/rsyncshot
+sudo rm -rf /etc/rsyncshot
+sudo rm /var/log/rsyncshot.log  # optional
+sudo crontab -e  # remove rsyncshot entries
+#+end_src
+
+* Testing
+
+An automated test suite is included in the =tests/= directory.
+
+** Running Tests
+
+#+begin_src sh
+# Run all tests (requires sudo)
+sudo ./tests/test_rsyncshot.sh
+
+# Skip slow backup/cron tests
+sudo ./tests/test_rsyncshot.sh --quick
+
+# Verbose output
+sudo ./tests/test_rsyncshot.sh -v
+#+end_src
+
+** Test Coverage
+
+| Category    | Tests | Description                                          |
+|-------------+-------+------------------------------------------------------|
+| Validation  |     6 | Input validation, help command, argument checking    |
+| Include     |     5 | Path parsing, comments, empty lines, spaces in paths |
+| Dry-run     |     4 | Preview mode doesn't modify anything                 |
+| Backup      |     7 | Directory creation, file copying, rotation, retention, exclusions |
+| Cron        |     3 | Cron job management, no duplicates, preserves existing jobs |
+
+** Test Structure
+
+- =tests/test_rsyncshot.sh= - Main test runner
+- =tests/lib/test_helpers.sh= - Assertion functions and test environment setup
+- =tests/cases/test_validation.sh= - Input validation tests
+- =tests/cases/test_includes.sh= - Include file parsing tests
+- =tests/cases/test_dryrun.sh= - Dry-run mode tests
+- =tests/cases/test_backup.sh= - Backup and rotation tests
+- =tests/cases/test_cron.sh= - Cron job management tests
+
+* License
+
+GPL v3. See [[file:LICENSE][LICENSE]] file.
diff --git a/rsyncshot b/rsyncshot
index 471168c..ead2e11 100755
--- a/rsyncshot
+++ b/rsyncshot
@@ -1,188 +1,975 @@
 #!/usr/bin/env bash
 
-# rsyncshot
-# convenient backups using rsync and hard links
-
-# Craig Jennings <c@cjennings.net>
-# Inspired by Mike Rubel: http://www.mikerubel.org/computers/rsync_snapshots/
-# requirements: bash, rsync, flock, cron, grep
-# - unix filesystem capable of hard links at destination
-# - core unix utilities: rm, mv, cp, touch
-
-# debugging: uncomment next 4 lines for debugging output
+# ==============================================================================
+# rsyncshot - Compact Snapshots Using rsync and Hard Links
+# ==============================================================================
+#
+# Creates space-efficient incremental backups using rsync and hard links.
+# Supports both local mount destinations (USB drives, NFS) and remote SSH.
+#
+# Author: Craig Jennings <c@cjennings.net>
+# Inspired by: Mike Rubel (http://www.mikerubel.org/computers/rsync_snapshots/)
+#
+# REQUIREMENTS:
+#   - bash, rsync, flock, cron, grep
+#   - Unix filesystem capable of hard links at destination
+#   - Core unix utilities: rm, mv, cp, touch
+#   - For remote mode: ssh with key-based authentication
+#     (set SSH_IDENTITY_FILE in config if key is not in root's ~/.ssh/)
+#
+# USAGE:
+#   rsyncshot <name> <count>   Run backup with snapshot name and retention count
+#   rsyncshot backup           Run immediate one-off backup (alias for 'manual 1')
+#   rsyncshot setup            Install script, create config files, add cron jobs
+#   rsyncshot status           Show installation and environment status
+#   rsyncshot list             Show existing snapshots and sizes
+#   rsyncshot dryrun <n> <c>   Preview backup without making changes
+#   rsyncshot help             Display usage information
+#
+# EXAMPLES:
+#   rsyncshot hourly 24        Keep 24 hourly snapshots (hourly.0 through hourly.23)
+#   rsyncshot daily 7          Keep 7 daily snapshots
+#   rsyncshot weekly 4         Keep 4 weekly snapshots
+#   rsyncshot manual 1         One-off backup (manual.0 only)
+#   rsyncshot dryrun hourly 24 Preview what hourly backup would do
+#   rsyncshot list             Show all snapshots with timestamps and sizes
+#
+# CONFIGURATION:
+#   Settings are stored in /etc/rsyncshot/config (created by setup).
+#   Edit this file to change backup destination, not the script itself.
+#
+# HOW IT WORKS:
+#   1. rsync copies source directories to <destination>/latest/
+#   2. Oldest snapshot beyond retention count is deleted
+#   3. Existing snapshots are rotated (name.0 -> name.1, name.1 -> name.2, etc.)
+#   4. <destination>/latest/ is hard-linked to <destination>/name.0
+#
+#   Hard links mean unchanged files share disk space across all snapshots.
+#   Only modified files consume additional space.
+#
+# ==============================================================================
+
+# ------------------------------------------------------------------------------
+# DEBUG MODE
+# ------------------------------------------------------------------------------
+# Uncomment the following 4 lines to enable verbose debug output to syslog.
+# Useful for troubleshooting cron job failures.
+#
 # exec 5> >(logger -t $0)
 # BASH_XTRACEFD="5"
 # PS4='$LINENO: '
 # set -x
 
-# default locations for setup
-# modify MOUNTDIR to point to the mount point of your backup
-
-#  ---------------------------- Constants ----------------------------
-
-MOUNTDIR=/media/backup;
-SCRIPTLOC=/usr/local/bin/rsyncshot;
-DESTINATION=$MOUNTDIR/$HOSTNAME
-
-INSTALLHOME=/etc/rsyncshot
-LOGFILE=/var/log/rsyncshot.log;
-
-INCLUDES="$INSTALLHOME/include.txt";
-EXCLUDES="$INSTALLHOME/exclude.txt";
+# ==============================================================================
+# DEFAULT CONFIGURATION
+# ==============================================================================
+# These defaults are used if /etc/rsyncshot/config doesn't exist or doesn't
+# define a value. After running 'rsyncshot setup', edit /etc/rsyncshot/config
+# to customize settings.
+
+# ------------------------------------------------------------------------------
+# BACKUP MODE SELECTION
+# ------------------------------------------------------------------------------
+# rsyncshot supports two backup modes:
+#
+# REMOTE MODE (SSH):
+#   Backups are sent over the network via SSH to a remote server.
+#   Set REMOTE_HOST to the SSH hostname or IP address.
+#   Set REMOTE_PATH to the base backup directory on the remote server.
+#   The script will create <REMOTE_PATH>/<hostname>/ for this machine's backups.
+#
+#   Example:
+#     REMOTE_HOST="truenas"
+#     REMOTE_PATH="/mnt/vault/Backups"
+#   Result: Backups go to truenas:/mnt/vault/Backups/myhostname/
+#
+# LOCAL MODE (Mount):
+#   Backups are written to a locally mounted filesystem (USB drive, NFS, etc.).
+#   Set REMOTE_HOST="" (empty) to enable local mode.
+#   Set MOUNTDIR to the mount point of your backup drive.
+#   The script will attempt to mount the filesystem if not already mounted.
+#
+#   Example:
+#     REMOTE_HOST=""
+#     MOUNTDIR="/media/backup"
+#   Result: Backups go to /media/backup/myhostname/
+#
+# ------------------------------------------------------------------------------
+
+# Remote mode settings (defaults)
+REMOTE_HOST=""
+REMOTE_PATH=""
+
+# SSH identity file (optional, for remote mode)
+# If root's SSH key is in a non-standard location (e.g., a user's home directory),
+# specify the path here. Leave empty to use SSH's default key discovery.
+# Example: SSH_IDENTITY_FILE="/home/cjennings/.ssh/id_ed25519"
+SSH_IDENTITY_FILE=""
+
+# Local mode settings (defaults)
+MOUNTDIR="/media/backup"
+
+# ------------------------------------------------------------------------------
+# INSTALLATION PATHS
+# ------------------------------------------------------------------------------
+
+# Where to install the script for system-wide access
+# These can be overridden via environment variables for testing
+SCRIPTLOC="${SCRIPTLOC:-/usr/local/bin/rsyncshot}"
+
+# Directory for configuration files
+INSTALLHOME="${INSTALLHOME:-/etc/rsyncshot}"
+
+# Configuration file path
+CONFIGFILE="$INSTALLHOME/config"
+
+# Log file location for cron job output
+LOGFILE="${LOGFILE:-/var/log/rsyncshot.log}"
+
+# Paths to include and exclude configuration files
+INCLUDES="$INSTALLHOME/include.txt"    # Directories to back up (one per line)
+EXCLUDES="$INSTALLHOME/exclude.txt"    # Patterns to exclude (one per line)
+
+# ------------------------------------------------------------------------------
+# COMMAND ALIASES
+# ------------------------------------------------------------------------------
+# Use absolute paths to avoid issues with shell aliases that might add
+# interactive prompts (e.g., alias rm='rm -i'). Only used in local mode.
 
-# copy, move, and rm commands have been aliased by the user or distro
-# creator to require confirmation on certain actions.
-# using variables allows us to sidestep any alias
 CP="/usr/bin/cp"
 MV="/usr/bin/mv"
 RM="/usr/bin/rm"
 
-# prevent overlapping runs with flock
+# ------------------------------------------------------------------------------
+# CONCURRENCY CONTROL
+# ------------------------------------------------------------------------------
+# Use flock to prevent multiple instances from running simultaneously.
+# This is important when cron might trigger a new run before the previous
+# one completes (e.g., slow network, large backup).
+
 FLOCKCHECK="flock -x /tmp/rsyncshot.lock -c"
 
-# default cron job entries
-CRON_H="0 1-23 * * * "; # hourly on minute 0 from 1am to 11pm
-CRON_D="0 12 * * 1-6 ";  # daily at noon, monday - saturday
-CRON_W="0 12 * * 7 ";    # weekly at noon on sundays
+# ------------------------------------------------------------------------------
+# DEFAULT CRON SCHEDULE
+# ------------------------------------------------------------------------------
+# These schedules are installed by 'rsyncshot setup'. Modify as needed.
+#
+# Format: minute hour day-of-month month day-of-week
+#
+# Default schedule:
+#   - Hourly: Every hour from 1am to 11pm (not midnight to avoid daily/weekly)
+#   - Daily: Noon, Monday through Saturday
+#   - Weekly: Noon on Sundays
+
+CRON_H="0 1-23 * * * "   # Hourly: minute 0, hours 1-23, every day
+CRON_D="0 12 * * 1-6 "   # Daily: noon, Monday-Saturday
+CRON_W="0 12 * * 7 "     # Weekly: noon, Sunday
+
+# ==============================================================================
+# LOAD CONFIGURATION FILE
+# ==============================================================================
+# Source the config file if it exists, overriding defaults above.
+# This allows customization without editing the script.
+
+if [ -f "$CONFIGFILE" ]; then
+    # shellcheck source=/etc/rsyncshot/config
+    source "$CONFIGFILE"
+fi
+
+# ------------------------------------------------------------------------------
+# DERIVED PATHS (auto-configured based on mode)
+# ------------------------------------------------------------------------------
+# These are calculated from the settings above. Do not modify directly.
+
+if [ -n "$REMOTE_HOST" ]; then
+    # Remote mode: backup destination is on a remote server via SSH
+    REMOTE_DEST="$REMOTE_PATH/$HOSTNAME"           # Full path on remote server
+    DESTINATION="$REMOTE_HOST:$REMOTE_DEST"        # rsync-compatible remote path
+    MODE="remote"
+else
+    # Local mode: backup destination is a locally mounted filesystem
+    DESTINATION="$MOUNTDIR/$HOSTNAME"              # Local backup path
+    MODE="local"
+fi
+
+# ==============================================================================
+# UTILITY FUNCTIONS
+# ==============================================================================
 
-#  ------------------------ Utility Functions ------------------------
+# ------------------------------------------------------------------------------
+# help() - Display usage information
+# ------------------------------------------------------------------------------
+# Shows command syntax, current mode, and configuration details.
 
 help()
 {
     printf "\nrsyncshot - compact snapshots on Linux using rsync and hard links.\n\n"
-    printf "Usage:\nrsyncshot <name> <number of backups to retain>\n"
-    printf "          setup (installs rsyncshot and cron jobs)\n"
-    printf "          help  (prints this info)\n"
-    printf "Notes:\n"
-    printf '%s\n'  "- rsyncshot must be run as root"
-	printf '%s\n\n' "- install and log locations defined in script."
+    printf "Usage:\n"
+    printf "  rsyncshot <name> <count>   Create snapshot with given name and retention count\n"
+    printf "  rsyncshot backup           Run immediate one-off backup\n"
+    printf "  rsyncshot setup            Install script and configure cron jobs\n"
+    printf "  rsyncshot status           Show installation and environment status\n"
+    printf "  rsyncshot list             Show existing snapshots with sizes\n"
+    printf "  rsyncshot dryrun <n> <c>   Preview backup without making changes\n"
+    printf "  rsyncshot help             Show this help message\n"
+    printf "\nExamples:\n"
+    printf "  rsyncshot hourly 24        Keep 24 hourly snapshots\n"
+    printf "  rsyncshot daily 7          Keep 7 daily snapshots\n"
+    printf "  rsyncshot backup           Immediate one-off backup\n"
+    printf "  rsyncshot dryrun manual 1  Preview a manual backup\n"
+    printf "\nConfiguration:\n"
+    printf "  Config file: %s\n" "$CONFIGFILE"
+    printf "  Includes:    %s\n" "$INCLUDES"
+    printf "  Excludes:    %s\n" "$EXCLUDES"
+    printf "\nCurrent settings:\n"
+    printf '%s\n' "- rsyncshot must be run as root"
+
+    # Display mode-specific configuration
+    if [ "$MODE" = "remote" ]; then
+        printf '%s\n'   "- Mode: remote (SSH)"
+        printf '%s\n'   "- Remote host: $REMOTE_HOST"
+        printf '%s\n\n' "- Remote path: $REMOTE_PATH/$HOSTNAME"
+    else
+        printf '%s\n'   "- Mode: local (mount)"
+        printf '%s\n\n' "- Mount dir: $MOUNTDIR/$HOSTNAME"
+    fi
 }
 
+# ------------------------------------------------------------------------------
+# error() - Display error message and exit
+# ------------------------------------------------------------------------------
+# Arguments:
+#   $@ - Error message to display
+#
+# Outputs error to stderr and exits with code 1.
+
 error()
 {
-	echo "ERROR: $0:" "$@" 1>&2;
+    echo "ERROR: $0:" "$@" 1>&2
     echo "See \"rsyncshot help\" for usage."
-    exit 1;
+    exit 1
+}
+
+# ------------------------------------------------------------------------------
+# log() - Print timestamped log message
+# ------------------------------------------------------------------------------
+# Arguments:
+#   $@ - Message to log
+#
+# Outputs message with ISO timestamp prefix.
+
+log()
+{
+    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*"
+}
+
+# ------------------------------------------------------------------------------
+# run_cmd() - Execute a command locally or remotely based on mode
+# ------------------------------------------------------------------------------
+# Arguments:
+#   $@ - Command to execute (as a single string for remote, or arguments for local)
+#
+# In remote mode: Executes command on REMOTE_HOST via SSH
+# In local mode: Executes command locally using eval
+#
+# If SSH_IDENTITY_FILE is set, uses that key for SSH connections.
+# This abstraction allows the same rotation logic to work in both modes.
+
+run_cmd()
+{
+    if [ "$MODE" = "remote" ]; then
+        if [ -n "$SSH_IDENTITY_FILE" ]; then
+            ssh -i "$SSH_IDENTITY_FILE" "$REMOTE_HOST" "$@"
+        else
+            ssh "$REMOTE_HOST" "$@"
+        fi
+    else
+        eval "$@"
+    fi
+}
+
+# ------------------------------------------------------------------------------
+# get_base_path() - Return the base backup path for file operations
+# ------------------------------------------------------------------------------
+# Returns the path where snapshots are stored, appropriate for the current mode.
+#
+# Remote mode: Returns the path on the remote server (for use with run_cmd)
+# Local mode: Returns the local filesystem path
+#
+# This is needed because rsync uses "host:path" format, but ssh commands
+# and local operations need just the path portion.
+
+get_base_path()
+{
+    if [ "$MODE" = "remote" ]; then
+        echo "$REMOTE_DEST"
+    else
+        echo "$MOUNTDIR/$HOSTNAME"
+    fi
+}
+
+# ------------------------------------------------------------------------------
+# list_snapshots() - Display existing snapshots with timestamps and sizes
+# ------------------------------------------------------------------------------
+# Shows all snapshot directories at the backup destination, sorted by name,
+# with modification time and disk usage.
+
+list_snapshots()
+{
+    # Verify we can access the destination
+    if [ "$MODE" = "remote" ]; then
+        SSH_OPTS="-o BatchMode=yes -o ConnectTimeout=5"
+        if [ -n "$SSH_IDENTITY_FILE" ]; then
+            SSH_OPTS="$SSH_OPTS -i $SSH_IDENTITY_FILE"
+        fi
+        if ! ssh $SSH_OPTS "$REMOTE_HOST" "true" 2>/dev/null; then
+            error "Cannot connect to $REMOTE_HOST via SSH."
+        fi
+    else
+        if [ ! -d "$MOUNTDIR" ]; then
+            error "$MOUNTDIR doesn't exist."
+        fi
+        if ! grep -qs "$MOUNTDIR" /proc/mounts 2>/dev/null; then
+            error "$MOUNTDIR is not mounted."
+        fi
+    fi
+
+    BASE_PATH=$(get_base_path)
+
+    echo ""
+    echo "Snapshots at: $DESTINATION"
+    echo "============================================================"
+
+    # Build command to list snapshots with details
+    # Format: name, modification time, size
+    LIST_CMD="
+        if [ -d '$BASE_PATH' ]; then
+            cd '$BASE_PATH'
+            found=0
+            for dir in */ ; do
+                if [ -d \"\$dir\" ] && [ \"\$dir\" != '*/' ]; then
+                    found=1
+                    name=\$(basename \"\$dir\")
+                    mtime=\$(stat -c '%y' \"\$dir\" 2>/dev/null | cut -d'.' -f1)
+                    size=\$(du -sh \"\$dir\" 2>/dev/null | cut -f1)
+                    printf '%-20s %s  %s\n' \"\$name\" \"\$mtime\" \"\$size\"
+                fi
+            done | sort
+            if [ \"\$found\" -eq 0 ]; then
+                echo 'No snapshots found.'
+            fi
+        else
+            echo 'No snapshots found.'
+        fi
+    "
+
+    run_cmd "$LIST_CMD"
+    echo ""
 }
 
+# ------------------------------------------------------------------------------
+# show_status() - Display installation and environment status
+# ------------------------------------------------------------------------------
+# Shows comprehensive status of rsyncshot installation, configuration,
+# destination accessibility, and cron job status.
+
+show_status()
+{
+    echo ""
+    echo "rsyncshot status"
+    echo "============================================================"
+
+    # --- Installation status ---
+    echo ""
+    echo "Installation:"
+    if [ -x "$SCRIPTLOC" ]; then
+        echo "  ✓ Script installed at $SCRIPTLOC"
+    else
+        echo "  ✗ Script NOT installed (run 'rsyncshot setup')"
+    fi
+
+    # --- Configuration files ---
+    echo ""
+    echo "Configuration:"
+    if [ -f "$CONFIGFILE" ]; then
+        echo "  ✓ Config file: $CONFIGFILE"
+    else
+        echo "  ✗ Config file NOT found: $CONFIGFILE"
+    fi
+
+    if [ -f "$INCLUDES" ]; then
+        # Count non-empty, non-comment lines
+        INCLUDE_COUNT=$(grep -cv '^[[:space:]]*#\|^[[:space:]]*$' "$INCLUDES" 2>/dev/null || echo 0)
+        echo "  ✓ Include file: $INCLUDES ($INCLUDE_COUNT directories)"
+    else
+        echo "  ✗ Include file NOT found: $INCLUDES"
+    fi
+
+    if [ -f "$EXCLUDES" ]; then
+        EXCLUDE_COUNT=$(grep -cv '^#\|^$' "$EXCLUDES" 2>/dev/null || echo 0)
+        echo "  ✓ Exclude file: $EXCLUDES ($EXCLUDE_COUNT patterns)"
+    else
+        echo "  ✗ Exclude file NOT found: $EXCLUDES"
+    fi
+
+    # --- Backup mode and destination ---
+    echo ""
+    echo "Backup Destination:"
+    echo "  Mode: $MODE"
+
+    if [ "$MODE" = "remote" ]; then
+        echo "  Remote host: $REMOTE_HOST"
+        echo "  Remote path: $REMOTE_PATH/$HOSTNAME"
+
+        if [ -n "$SSH_IDENTITY_FILE" ]; then
+            if [ -f "$SSH_IDENTITY_FILE" ]; then
+                echo "  ✓ SSH key: $SSH_IDENTITY_FILE"
+            else
+                echo "  ✗ SSH key NOT found: $SSH_IDENTITY_FILE"
+            fi
+        else
+            echo "  SSH key: (using default)"
+        fi
+
+        # Test SSH connectivity
+        SSH_OPTS="-o BatchMode=yes -o ConnectTimeout=5"
+        if [ -n "$SSH_IDENTITY_FILE" ]; then
+            SSH_OPTS="$SSH_OPTS -i $SSH_IDENTITY_FILE"
+        fi
+        if ssh $SSH_OPTS "$REMOTE_HOST" "true" 2>/dev/null; then
+            echo "  ✓ SSH connection: OK"
+
+            # Check if backup directory exists
+            if run_cmd "[ -d '$REMOTE_DEST' ]" 2>/dev/null; then
+                echo "  ✓ Backup directory exists"
+            else
+                echo "  ✗ Backup directory NOT found (will be created on first backup)"
+            fi
+        else
+            echo "  ✗ SSH connection: FAILED"
+        fi
+    else
+        echo "  Mount point: $MOUNTDIR"
+
+        if [ -d "$MOUNTDIR" ]; then
+            echo "  ✓ Mount point exists"
+
+            if grep -qs "$MOUNTDIR" /proc/mounts 2>/dev/null; then
+                echo "  ✓ Filesystem mounted"
+
+                if [ -d "$MOUNTDIR/$HOSTNAME" ]; then
+                    echo "  ✓ Backup directory exists"
+                else
+                    echo "  ✗ Backup directory NOT found (will be created on first backup)"
+                fi
+            else
+                echo "  ✗ Filesystem NOT mounted"
+            fi
+        else
+            echo "  ✗ Mount point does NOT exist"
+        fi
+    fi
+
+    # --- Cron jobs ---
+    echo ""
+    echo "Scheduled Backups:"
+    CRON_JOBS=$(crontab -l 2>/dev/null | grep -c "rsyncshot" || echo 0)
+    if [ "$CRON_JOBS" -gt 0 ]; then
+        echo "  ✓ $CRON_JOBS cron job(s) installed:"
+        crontab -l 2>/dev/null | grep "rsyncshot" | while read -r line; do
+            # Extract the backup type from the cron line
+            if echo "$line" | grep -q "hourly"; then
+                SCHED=$(echo "$line" | awk '{print $1, $2, $3, $4, $5}')
+                echo "    - hourly: $SCHED"
+            elif echo "$line" | grep -q "daily"; then
+                SCHED=$(echo "$line" | awk '{print $1, $2, $3, $4, $5}')
+                echo "    - daily:  $SCHED"
+            elif echo "$line" | grep -q "weekly"; then
+                SCHED=$(echo "$line" | awk '{print $1, $2, $3, $4, $5}')
+                echo "    - weekly: $SCHED"
+            fi
+        done
+    else
+        echo "  ✗ No cron jobs installed (run 'rsyncshot setup')"
+    fi
+
+    # --- Log file ---
+    echo ""
+    echo "Logging:"
+    if [ -f "$LOGFILE" ]; then
+        LOG_SIZE=$(du -h "$LOGFILE" 2>/dev/null | cut -f1)
+        LOG_LINES=$(wc -l < "$LOGFILE" 2>/dev/null)
+        echo "  ✓ Log file: $LOGFILE ($LOG_SIZE, $LOG_LINES lines)"
+
+        # Show last backup time from log
+        LAST_BACKUP=$(grep "completed successfully" "$LOGFILE" 2>/dev/null | tail -1)
+        if [ -n "$LAST_BACKUP" ]; then
+            # Extract timestamp from [YYYY-MM-DD HH:MM:SS] format (portable, no Perl regex)
+            LAST_TIME=$(echo "$LAST_BACKUP" | sed 's/.*\[\([^]]*\)\].*/\1/')
+            echo "  Last successful backup: $LAST_TIME"
+        fi
+    else
+        echo "  ✗ Log file NOT found: $LOGFILE"
+    fi
+
+    # --- Snapshots summary ---
+    echo ""
+    echo "Snapshots:"
+    if [ "$MODE" = "remote" ]; then
+        if ssh $SSH_OPTS "$REMOTE_HOST" "true" 2>/dev/null; then
+            SNAP_COUNT=$(run_cmd "ls -d '$REMOTE_DEST'/*/ 2>/dev/null | wc -l" 2>/dev/null || echo 0)
+            if [ "$SNAP_COUNT" -gt 0 ]; then
+                echo "  $SNAP_COUNT snapshot(s) found (run 'rsyncshot list' for details)"
+            else
+                echo "  No snapshots found"
+            fi
+        else
+            echo "  (cannot check - SSH connection failed)"
+        fi
+    else
+        if [ -d "$MOUNTDIR/$HOSTNAME" ]; then
+            SNAP_COUNT=$(ls -d "$MOUNTDIR/$HOSTNAME"/*/ 2>/dev/null | wc -l || echo 0)
+            if [ "$SNAP_COUNT" -gt 0 ]; then
+                echo "  $SNAP_COUNT snapshot(s) found (run 'rsyncshot list' for details)"
+            else
+                echo "  No snapshots found"
+            fi
+        else
+            echo "  (backup directory does not exist)"
+        fi
+    fi
+
+    echo ""
+}
+
+# ------------------------------------------------------------------------------
+# setup() - Install rsyncshot and configure the system
+# ------------------------------------------------------------------------------
+# Performs initial setup:
+#   1. Verifies connectivity (SSH for remote, mount point for local)
+#   2. Copies script to /usr/local/bin/rsyncshot
+#   3. Creates /etc/rsyncshot/ directory
+#   4. Creates config file with current settings
+#   5. Creates default include.txt (directories to back up)
+#   6. Creates default exclude.txt (patterns to skip)
+#   7. Creates backup destination directory
+#   8. Installs cron jobs for automated backups
+#
+# After setup, edit /etc/rsyncshot/config, include.txt, and exclude.txt as needed.
+
 setup()
 {
-    # copy this file to directory on path and make executable
-	$CP -f "$0" "$SCRIPTLOC"
-	sudo chmod +x "$SCRIPTLOC"
-	echo "$0 copied to $SCRIPTLOC and made executable"
-
-    # make install home if it doesn't exist;
-    if [ ! -d $INSTALLHOME ]; then
-	   mkdir -p $INSTALLHOME;
-	   echo "Created install home at $INSTALLHOME";
-    fi
-
-    # create includes file and add default entries
-    if [ -f $INCLUDES ]; then $RM $INCLUDES; fi
-    printf "/home /etc /usr/local/bin" >> $INCLUDES;
-    echo "modify include file at $INCLUDES";
-
-    # create excludes file and add default entries
-    if [ -f $EXCLUDES ]; then $RM $EXCLUDES; fi
-    printf "*.pyc\n*.pyo\n*.class\n*.elc\n*.o\n*.tmp\n.cache*" >>  $EXCLUDES;
-    echo "modify exclude file at $EXCLUDES";
-
-	# write out current crontab, append default entries, and install
-	touch "$LOGFILE"
-	crontab -l > crontemp;
-	{
-		echo "$CRON_H $FLOCKCHECK '$SCRIPTLOC hourly 22 >> $LOGFILE 2>&1'"
-		echo "$CRON_D $FLOCKCHECK '$SCRIPTLOC daily 6 >> $LOGFILE 2>&1'"
-		echo "$CRON_W $FLOCKCHECK '$SCRIPTLOC weekly 51 >> $LOGFILE 2>&1'"
-	} >> crontemp
-    crontab crontemp;
-    $RM crontemp;
-    echo "hourly, daily, and weekly cron jobs installed.";
+    # --- Verify destination is accessible ---
+    if [ "$MODE" = "remote" ]; then
+        # Remote mode: test SSH connectivity with key-based auth
+        echo "Testing SSH connection to $REMOTE_HOST..."
+        SSH_TEST_OPTS="-o BatchMode=yes -o ConnectTimeout=5"
+        if [ -n "$SSH_IDENTITY_FILE" ]; then
+            SSH_TEST_OPTS="$SSH_TEST_OPTS -i $SSH_IDENTITY_FILE"
+        fi
+        if ! ssh $SSH_TEST_OPTS "$REMOTE_HOST" "echo 'SSH connection successful'" 2>/dev/null; then
+            error "Cannot connect to $REMOTE_HOST via SSH. Ensure SSH key auth is configured."
+        fi
+    else
+        # Local mode: verify mount directory exists
+        if [ ! -d "$MOUNTDIR" ]; then
+            error "$MOUNTDIR doesn't exist. Create it or update MOUNTDIR in script."
+        fi
+    fi
+
+    # --- Install script to system path ---
+    $CP -f "$0" "$SCRIPTLOC"
+    chmod +x "$SCRIPTLOC"
+    echo "$0 copied to $SCRIPTLOC and made executable"
+
+    # --- Create configuration directory ---
+    if [ ! -d "$INSTALLHOME" ]; then
+        mkdir -p "$INSTALLHOME"
+        echo "Created install home at $INSTALLHOME"
+    fi
+
+    # --- Create config file ---
+    # Contains the key settings that users will want to customize
+    cat > "$CONFIGFILE" << EOF
+# ==============================================================================
+# rsyncshot configuration
+# ==============================================================================
+# Edit this file to customize backup settings.
+# Changes take effect on next rsyncshot run.
+
+# ------------------------------------------------------------------------------
+# BACKUP MODE
+# ------------------------------------------------------------------------------
+# Set REMOTE_HOST for SSH mode, or leave empty for local mount mode.
+
+# Remote mode (SSH to a server):
+REMOTE_HOST="$REMOTE_HOST"
+REMOTE_PATH="$REMOTE_PATH"
+
+# SSH identity file (optional, for remote mode)
+# If running as root but your SSH key is in your user's home directory,
+# specify the full path here. Leave empty to use SSH's default key discovery.
+# Example: SSH_IDENTITY_FILE="/home/username/.ssh/id_ed25519"
+SSH_IDENTITY_FILE="$SSH_IDENTITY_FILE"
+
+# Local mode (USB drive, NFS mount, etc.):
+# REMOTE_HOST=""
+MOUNTDIR="$MOUNTDIR"
+EOF
+    echo "Created config file at $CONFIGFILE"
+
+    # --- Create include file (directories to back up) ---
+    # Default: /home (user data), /etc (system config), /usr/local/bin (custom scripts)
+    # Format: one directory per line (supports paths with spaces)
+    if [ -f "$INCLUDES" ]; then $RM "$INCLUDES"; fi
+    cat >> "$INCLUDES" << 'EOF'
+/home
+/etc
+/usr/local/bin
+EOF
+    echo "Modify include file at $INCLUDES"
+
+    # --- Create exclude file (patterns to skip) ---
+    # Default excludes: caches, temp files, compiled code, editor backups
+    # Format: one pattern per line (rsync --exclude-from format)
+    if [ -f "$EXCLUDES" ]; then $RM "$EXCLUDES"; fi
+    cat >> "$EXCLUDES" << 'EOF'
+# Compiled/bytecode files
+*.pyc
+*.pyo
+*.class
+*.elc
+*.o
+
+# Temporary files
+*.tmp
+*.swp
+*~
+
+# Cache directories
+.cache
+.cache*
+*/.cache/*
+
+# Trash and browser caches
+.local/share/Trash
+.mozilla/firefox/*/cache2
+.thunderbird/*/ImapMail
+
+# Package manager caches and build artifacts
+node_modules
+__pycache__
+
+# Log files (usually regenerated)
+*.log
+EOF
+    echo "Modify exclude file at $EXCLUDES"
+
+    # --- Create backup destination directory ---
+    BASE_PATH=$(get_base_path)
+    echo "Creating backup directory..."
+    run_cmd "mkdir -p '$BASE_PATH'"
+
+    # --- Install cron jobs ---
+    # Remove any existing rsyncshot entries, then add fresh ones
+    # This prevents duplicate entries if setup is run multiple times
+    touch "$LOGFILE"
+    CRONTEMP=$(mktemp)
+    crontab -l 2>/dev/null | grep -v "rsyncshot" > "$CRONTEMP" || true
+    {
+        echo "# rsyncshot automated backups"
+        echo "$CRON_H $FLOCKCHECK '$SCRIPTLOC hourly 22 >> $LOGFILE 2>&1'"
+        echo "$CRON_D $FLOCKCHECK '$SCRIPTLOC daily 6 >> $LOGFILE 2>&1'"
+        echo "$CRON_W $FLOCKCHECK '$SCRIPTLOC weekly 51 >> $LOGFILE 2>&1'"
+    } >> "$CRONTEMP"
+    crontab "$CRONTEMP"
+    $RM "$CRONTEMP"
+    echo "Hourly, daily, and weekly cron jobs installed."
+
+    # --- Display summary ---
+    echo ""
+    echo "Setup complete. Configuration:"
+    echo "  Mode:           $MODE"
+    if [ "$MODE" = "remote" ]; then
+        echo "  Remote host:    $REMOTE_HOST"
+        echo "  Remote path:    $REMOTE_DEST"
+    else
+        echo "  Mount dir:      $MOUNTDIR"
+        echo "  Destination:    $DESTINATION"
+    fi
+    echo "  Config file:    $CONFIGFILE"
+    echo "  Includes:       $INCLUDES"
+    echo "  Excludes:       $EXCLUDES"
+    echo "  Log file:       $LOGFILE"
+    echo ""
+    echo "Next steps:"
+    echo "  1. Edit $CONFIGFILE to set backup destination"
+    echo "  2. Edit $INCLUDES to specify directories to back up"
+    echo "  3. Edit $EXCLUDES to add any additional exclusion patterns"
+    echo "  4. Run 'sudo rsyncshot dryrun manual 1' to preview"
+    echo "  5. Run 'sudo rsyncshot manual 1' to test"
 }
 
-#  ----------------------------- Script ----------------------------
+# ==============================================================================
+# MAIN SCRIPT
+# ==============================================================================
 
-# uppercase for case-insensitivity
-TYPE=$(tr '[a-z]' '[A-Z]' <<< $1);
+# --- Handle help command (before root check, so anyone can view help) ---
+TYPE=$(tr '[:lower:]' '[:upper:]' <<< "$1")
 if [ "$TYPE" = "HELP" ]; then help; exit; fi
 
-# ensure we're running as root
+# --- Verify running as root ---
+# Root is required for:
+#   - Reading all files in /home and /etc
+#   - Writing to /var/log and /usr/local/bin
+#   - Installing cron jobs
 if [ "$EUID" -ne 0 ]; then error "This script must be run as root."; fi
 
-# display start information
-echo "rsyncshot invoked on $(date -u) with: $0 $1 $2";
+# --- Verify required commands exist ---
+if ! command -v rsync &> /dev/null; then
+    echo "ERROR: rsync is not installed." 1>&2
+    echo ""
+    echo "Install rsync using your package manager:"
+    echo "  Arch Linux:    sudo pacman -S rsync"
+    echo "  Debian/Ubuntu: sudo apt install rsync"
+    echo "  Fedora/RHEL:   sudo dnf install rsync"
+    echo "  macOS:         brew install rsync"
+    exit 1
+fi
+
+if ! command -v flock &> /dev/null; then
+    echo "ERROR: flock is not installed (required for cron job locking)." 1>&2
+    echo ""
+    echo "Install flock using your package manager:"
+    echo "  Arch Linux:    sudo pacman -S util-linux"
+    echo "  Debian/Ubuntu: sudo apt install util-linux"
+    echo "  Fedora/RHEL:   sudo dnf install util-linux"
+    echo "  macOS:         brew install flock"
+    exit 1
+fi
+
+if [ "$MODE" = "remote" ] && ! command -v ssh &> /dev/null; then
+    echo "ERROR: ssh is not installed (required for remote mode)." 1>&2
+    echo ""
+    echo "Install openssh using your package manager:"
+    echo "  Arch Linux:    sudo pacman -S openssh"
+    echo "  Debian/Ubuntu: sudo apt install openssh-client"
+    echo "  Fedora/RHEL:   sudo dnf install openssh-clients"
+    exit 1
+fi
+
+# --- Handle list command ---
+if [ "$TYPE" = "LIST" ]; then list_snapshots; exit; fi
 
-# if logfile was removed, recreate it.
-[ ! -f "$LOGFILE" ] || touch "$LOGFILE"
+# --- Handle status command ---
+if [ "$TYPE" = "STATUS" ]; then show_status; exit; fi
 
-# validate backup type
-# first argument must be alpha characters
-if ! [[ $1 =~ [a-zA-Z] ]]; then error "snapshot type not recognized."; fi
+# --- Handle backup command (immediate one-off backup) ---
+# 'rsyncshot backup' is a convenient alias for 'rsyncshot manual 1'
+if [ "$TYPE" = "BACKUP" ]; then
+    set -- "manual" "1"  # Replace arguments
+    TYPE="MANUAL"
+fi
+
+# --- Handle dryrun command ---
+# Dryrun mode: show what would be backed up without making changes
+DRYRUN=false
+if [ "$TYPE" = "DRYRUN" ]; then
+    DRYRUN=true
+    shift  # Remove 'dryrun' from arguments, process remaining as normal
+    TYPE=$(tr '[:lower:]' '[:upper:]' <<< "$1")
+fi
+
+# --- Log invocation ---
+if [ "$DRYRUN" = true ]; then
+    log "rsyncshot DRYRUN invoked with: $0 $1 $2 (mode: $MODE)"
+else
+    log "rsyncshot invoked with: $0 $1 $2 (mode: $MODE)"
+fi
+
+# --- Ensure log file exists ---
+[ -f "$LOGFILE" ] || touch "$LOGFILE"
+
+# --- Validate first argument (snapshot type) ---
+# Must be alphabetic only (e.g., "hourly", "daily", "weekly", "manual")
+if ! [[ $1 =~ ^[a-zA-Z]+$ ]]; then error "snapshot type must be alphabetic (e.g., hourly, daily, manual)."; fi
+
+# --- Handle setup command ---
 if [ "$TYPE" = "SETUP" ]; then setup; exit; fi
 
-# validate max snapshots
-# second argument must be numeric
-if ! [[ $2 =~ [0-9] ]]; then error "max snapshots not a number."; fi
-MAX=$(($2-1));
+# --- Validate second argument (retention count) ---
+# Must be numeric only (e.g., 24 for 24 hourly snapshots)
+if ! [[ $2 =~ ^[0-9]+$ ]]; then error "max snapshots must be a number (e.g., 24)."; fi
+MAX=$(($2-1))  # Convert count to max index (e.g., 24 -> 23 for indices 0-23)
 
-# validate include file (source directories) exist
-# validates the include file exists, and checks the file contents are valid directories
+# --- Validate include file exists and contains valid directories ---
 if [ ! -f "$INCLUDES" ]; then error "include file $INCLUDES not found."; fi
-SOURCES=$(<$INCLUDES);
-for SOURCE in $SOURCES
-do
+
+# Read include file line by line (supports paths with spaces)
+while IFS= read -r SOURCE || [ -n "$SOURCE" ]; do
+    # Skip empty lines and comments
+    [[ -z "$SOURCE" || "$SOURCE" =~ ^[[:space:]]*# ]] && continue
     if [ ! -d "$SOURCE" ]; then error "source $SOURCE not found"; fi
-done
+done < "$INCLUDES"
 
-# validate exclude file (exclusion patterns) exist
+# --- Validate exclude file exists ---
 if [ ! -f "$EXCLUDES" ]; then error "Exclude file $EXCLUDES not found."; fi
 
-[ -d $MOUNTDIR ] || error "$MOUNTDIR doesn't exist."
+# --- Mode-specific destination validation ---
+if [ "$MODE" = "remote" ]; then
+    # Verify SSH identity file exists if specified
+    if [ -n "$SSH_IDENTITY_FILE" ] && [ ! -f "$SSH_IDENTITY_FILE" ]; then
+        error "SSH identity file not found: $SSH_IDENTITY_FILE"
+    fi
 
-# if destination filesystem not mounted attempt mounting; error if attempt fails
-if ! grep -qs "$MOUNTDIR" /proc/mounts >> /dev/null 2>&1; then
-	mount "$MOUNTDIR" >> /dev/null 2>&1
-	if ! grep -qs "$MOUNTDIR" /proc/mounts >> /dev/null 2>&1; then
-		error "$MOUNTDIR not mounted and mount attempt failed."
-	fi
+    # Remote mode: verify SSH connectivity
+    # Uses BatchMode to fail immediately if key auth doesn't work
+    # Uses ConnectTimeout to fail quickly if host is unreachable
+    SSH_OPTS="-o BatchMode=yes -o ConnectTimeout=10"
+    if [ -n "$SSH_IDENTITY_FILE" ]; then
+        SSH_OPTS="$SSH_OPTS -i $SSH_IDENTITY_FILE"
+    fi
+    if ! ssh $SSH_OPTS "$REMOTE_HOST" "true" 2>/dev/null; then
+        error "Cannot connect to $REMOTE_HOST via SSH."
+    fi
+else
+    # Local mode: verify mount point exists
+    [ -d "$MOUNTDIR" ] || error "$MOUNTDIR doesn't exist."
+
+    # Attempt to mount if not already mounted
+    # This supports fstab entries with 'noauto' option
+    # RSYNCSHOT_SKIP_MOUNT_CHECK can be set for testing purposes
+    if [ "${RSYNCSHOT_SKIP_MOUNT_CHECK:-}" != "1" ]; then
+        if ! grep -qs "$MOUNTDIR" /proc/mounts >> /dev/null 2>&1; then
+            mount "$MOUNTDIR" >> /dev/null 2>&1
+            if ! grep -qs "$MOUNTDIR" /proc/mounts >> /dev/null 2>&1; then
+                error "$MOUNTDIR not mounted and mount attempt failed."
+            fi
+        fi
+    fi
 fi
 
-[ -d "$DESTINATION" ] || mkdir "$DESTINATION" || \
-	error "$DESTINATION doesn't exist, and attempt to create directory failed."
+# --- Get base path for file operations ---
+BASE_PATH=$(get_base_path)
 
-# sync each backup directory in turn
-for SOURCE in $SOURCES
-do
-    rsync -avh -i --times \
-    	  --delete  --delete-excluded \
-		  --exclude-from="$EXCLUDES" \
-		  --update "$SOURCE" "$DESTINATION"/latest ;
-done
+# --- Ensure destination directory structure exists ---
+if [ "$DRYRUN" = false ]; then
+    run_cmd "mkdir -p '$BASE_PATH/latest'"
+fi
 
-# delete max+1 snapshot if it exists
-if [ -d "$DESTINATION"/"$TYPE"."$MAX" ]; then
-	$RM -rf "$DESTINATION"/"$TYPE"."$MAX";
+# ==============================================================================
+# BACKUP PHASE: Sync source directories to destination
+# ==============================================================================
+# rsync options:
+#   -a          Archive mode (preserves permissions, timestamps, symlinks, etc.)
+#   -v          Verbose output
+#   -h          Human-readable sizes
+#   --times     Preserve modification times
+#   --delete    Delete files in destination that don't exist in source
+#   --delete-excluded  Also delete excluded files from destination
+#   --exclude-from     Read exclusion patterns from file
+#   --dry-run   Show what would be transferred without making changes
+
+# Track if any rsync operation fails
+RSYNC_FAILED=false
+
+# Set RSYNC_RSH environment variable if using custom SSH identity
+# rsync automatically uses this variable for the remote shell command
+if [ "$MODE" = "remote" ] && [ -n "$SSH_IDENTITY_FILE" ]; then
+    export RSYNC_RSH="ssh -i $SSH_IDENTITY_FILE"
+fi
+
+# Read include file and sync each directory
+while IFS= read -r SOURCE || [ -n "$SOURCE" ]; do
+    # Skip empty lines and comments
+    [[ -z "$SOURCE" || "$SOURCE" =~ ^[[:space:]]*# ]] && continue
+
+    log "Syncing $SOURCE to $DESTINATION/latest"
+
+    if [ "$DRYRUN" = true ]; then
+        # Dry run: show what would be transferred
+        rsync -avh --times \
+              --delete --delete-excluded \
+              --exclude-from="$EXCLUDES" \
+              --dry-run \
+              "$SOURCE" "$DESTINATION"/latest
+        RSYNC_EXIT=$?
+    else
+        # Actual backup
+        rsync -avh --times \
+              --delete --delete-excluded \
+              --exclude-from="$EXCLUDES" \
+              "$SOURCE" "$DESTINATION"/latest
+        RSYNC_EXIT=$?
+    fi
 
+    # Check rsync exit code
+    if [ $RSYNC_EXIT -ne 0 ]; then
+        echo "ERROR: rsync failed for $SOURCE (exit code: $RSYNC_EXIT)" 1>&2
+        RSYNC_FAILED=true
+    fi
+done < "$INCLUDES"
+
+# --- Abort if rsync failed ---
+# Don't rotate snapshots if the backup didn't complete successfully
+if [ "$RSYNC_FAILED" = true ]; then
+    error "Backup failed. Snapshot rotation skipped to preserve existing backups."
 fi
 
-# rotate remaining snapshots descending
-for (( start=$((MAX)); start>=0; start--)); do
-	end=$((start+1));
-	if [ -d "$DESTINATION"/"$TYPE".$start ]; then
-		$MV "$DESTINATION"/"$TYPE".$start "$DESTINATION"/"$TYPE".$end;
-	fi
+# --- Exit here if dry run ---
+if [ "$DRYRUN" = true ]; then
+    log "Dry run complete. No changes were made."
+    echo ""
+    echo "To perform actual backup, run without 'dryrun':"
+    echo "  sudo rsyncshot $1 $2"
+    exit 0
+fi
+
+# ==============================================================================
+# ROTATION PHASE: Manage snapshot history
+# ==============================================================================
+# Snapshot naming: TYPE.N where N is the age (0 = newest, MAX = oldest)
+#
+# Example with "hourly 4" (keep 4 snapshots, indices 0-3, MAX=3):
+#   Before: hourly.0, hourly.1, hourly.2, hourly.3
+#   Step 1: Delete hourly.3 (oldest, beyond retention)
+#   Step 2: Rotate: hourly.2 -> hourly.3, hourly.1 -> hourly.2, hourly.0 -> hourly.1
+#   Step 3: Hard-link latest/ to hourly.0 (newest snapshot)
+#   After: hourly.0 (new), hourly.1, hourly.2, hourly.3
+
+log "Rotating snapshots..."
+
+# --- Delete oldest snapshot if it exceeds retention count ---
+if run_cmd "[ -d '$BASE_PATH/$TYPE.$MAX' ]"; then
+    log "Deleting oldest snapshot: $TYPE.$MAX"
+    run_cmd "rm -rf '$BASE_PATH/$TYPE.$MAX'"
+fi
+
+# --- Rotate existing snapshots (newest to oldest to avoid overwriting) ---
+for (( start=$((MAX)); start>=0; start-- )); do
+    end=$((start+1))
+    if run_cmd "[ -d '$BASE_PATH/$TYPE.$start' ]"; then
+        log "Rotating: $TYPE.$start -> $TYPE.$end"
+        run_cmd "mv '$BASE_PATH/$TYPE.$start' '$BASE_PATH/$TYPE.$end'"
+    fi
 done
 
-# reset directory timestamp
-touch "$DESTINATION"/latest
+# --- Update timestamp on latest/ directory ---
+run_cmd "touch '$BASE_PATH/latest'"
+
+# --- Create new snapshot using hard links ---
+# cp -al creates a copy where all files are hard links to the originals.
+# This is instant and uses no additional disk space for unchanged files.
+# Only files that differ between snapshots consume extra space.
+log "Creating new snapshot: $TYPE.0"
+run_cmd "cp -al '$BASE_PATH/latest' '$BASE_PATH/$TYPE.0'"
 
-# hard link / copy to destination
-$CP -al "$DESTINATION"/latest "$DESTINATION"/"$TYPE".0;
+# --- Make snapshot read-only to prevent accidental modification ---
+run_cmd "chmod -w '$BASE_PATH/$TYPE.0'"
 
-# make directory type read-only
-chmod -w "$DESTINATION"/"$TYPE".0
+# ==============================================================================
+# COMPLETION
+# ==============================================================================
 
-# print time and exit
-echo "rsyncshot completed $(date -u) ";
-exit 0;
+log "rsyncshot completed successfully"
+exit 0
diff --git a/tests/cases/test_backup.sh b/tests/cases/test_backup.sh
new file mode 100755
index 0000000..1ab4fbd
--- /dev/null
+++ b/tests/cases/test_backup.sh
@@ -0,0 +1,239 @@
+#!/usr/bin/env bash
+# ==============================================================================
+# Backup and Rotation Tests
+# ==============================================================================
+
+source "$(dirname "${BASH_SOURCE[0]}")/../lib/test_helpers.sh"
+
+# ------------------------------------------------------------------------------
+# Test: Creates backup directory structure
+# ------------------------------------------------------------------------------
+test_creates_backup_structure() {
+    setup_test_env
+
+    create_test_config
+    create_test_includes
+    create_test_excludes
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" manual 1 2>&1)
+    local exit_code=$?
+
+    # Check directory structure
+    assert_dir_exists "$TEST_BACKUP_DIR/$HOSTNAME" "should create hostname dir" || {
+        teardown_test_env
+        return 1
+    }
+    assert_dir_exists "$TEST_BACKUP_DIR/$HOSTNAME/latest" "should create latest dir" || {
+        teardown_test_env
+        return 1
+    }
+    assert_dir_exists "$TEST_BACKUP_DIR/$HOSTNAME/MANUAL.0" "should create MANUAL.0 snapshot" || {
+        teardown_test_env
+        return 1
+    }
+
+    teardown_test_env
+}
+
+# ------------------------------------------------------------------------------
+# Test: Copies files to backup
+# ------------------------------------------------------------------------------
+test_copies_files() {
+    setup_test_env
+
+    create_test_config
+    create_test_includes
+    create_test_excludes
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" manual 1 2>&1)
+
+    # Check files were copied
+    assert_file_exists "$TEST_BACKUP_DIR/$HOSTNAME/latest/home/testuser/file1.txt" "should copy file1.txt" || {
+        teardown_test_env
+        return 1
+    }
+    assert_file_exists "$TEST_BACKUP_DIR/$HOSTNAME/latest/etc/test.conf" "should copy test.conf" || {
+        teardown_test_env
+        return 1
+    }
+
+    teardown_test_env
+}
+
+# ------------------------------------------------------------------------------
+# Test: Snapshot is read-only
+# ------------------------------------------------------------------------------
+test_snapshot_readonly() {
+    setup_test_env
+
+    create_test_config
+    create_test_includes
+    create_test_excludes
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" manual 1 2>&1)
+
+    # Check snapshot directory has no write permission
+    # Note: We use stat to check actual permissions because -w always returns true for root
+    local perms
+    perms=$(stat -c '%A' "$TEST_BACKUP_DIR/$HOSTNAME/MANUAL.0" 2>/dev/null)
+    if [[ "$perms" == *w* ]]; then
+        echo "FAIL: Snapshot should be read-only (perms: $perms)"
+        teardown_test_env
+        return 1
+    fi
+
+    teardown_test_env
+    return 0
+}
+
+# ------------------------------------------------------------------------------
+# Test: Rotation works correctly
+# ------------------------------------------------------------------------------
+test_rotation() {
+    setup_test_env
+
+    create_test_config
+    create_test_includes
+    create_test_excludes
+
+    # Run backup twice
+    sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" manual 3 2>&1 >/dev/null
+    sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" manual 3 2>&1 >/dev/null
+
+    # Should have MANUAL.0 and MANUAL.1
+    assert_dir_exists "$TEST_BACKUP_DIR/$HOSTNAME/MANUAL.0" "should have MANUAL.0" || {
+        teardown_test_env
+        return 1
+    }
+    assert_dir_exists "$TEST_BACKUP_DIR/$HOSTNAME/MANUAL.1" "should have MANUAL.1 after rotation" || {
+        teardown_test_env
+        return 1
+    }
+
+    teardown_test_env
+}
+
+# ------------------------------------------------------------------------------
+# Test: Deletes oldest snapshot beyond retention
+# ------------------------------------------------------------------------------
+test_retention_limit() {
+    setup_test_env
+
+    create_test_config
+    create_test_includes
+    create_test_excludes
+
+    # Run backup 4 times with retention of 3
+    for i in 1 2 3 4; do
+        sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" manual 3 2>&1 >/dev/null
+    done
+
+    # Should have MANUAL.0, MANUAL.1, MANUAL.2 but NOT MANUAL.3
+    assert_dir_exists "$TEST_BACKUP_DIR/$HOSTNAME/MANUAL.0" "should have MANUAL.0" || {
+        teardown_test_env
+        return 1
+    }
+    assert_dir_exists "$TEST_BACKUP_DIR/$HOSTNAME/MANUAL.1" "should have MANUAL.1" || {
+        teardown_test_env
+        return 1
+    }
+    assert_dir_exists "$TEST_BACKUP_DIR/$HOSTNAME/MANUAL.2" "should have MANUAL.2" || {
+        teardown_test_env
+        return 1
+    }
+    assert_dir_not_exists "$TEST_BACKUP_DIR/$HOSTNAME/MANUAL.3" "should NOT have MANUAL.3 (beyond retention)" || {
+        teardown_test_env
+        return 1
+    }
+
+    teardown_test_env
+}
+
+# ------------------------------------------------------------------------------
+# Test: Backup command works as alias
+# ------------------------------------------------------------------------------
+test_backup_command() {
+    setup_test_env
+
+    create_test_config
+    create_test_includes
+    create_test_excludes
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" backup 2>&1)
+    local exit_code=$?
+
+    # Should create MANUAL.0 (backup is alias for manual 1)
+    assert_dir_exists "$TEST_BACKUP_DIR/$HOSTNAME/MANUAL.0" "backup should create MANUAL.0" || {
+        teardown_test_env
+        return 1
+    }
+
+    teardown_test_env
+}
+
+# ------------------------------------------------------------------------------
+# Test: Excludes files matching patterns
+# ------------------------------------------------------------------------------
+test_excludes_patterns() {
+    setup_test_env
+
+    create_test_config
+    create_test_includes
+
+    # Create exclude file
+    cat > "$TEST_CONFIG_DIR/exclude.txt" << 'EOF'
+*.tmp
+*.log
+EOF
+
+    # Create files that should be excluded
+    echo "temp" > "$TEST_SOURCE_DIR/home/testuser/temp.tmp"
+    echo "log" > "$TEST_SOURCE_DIR/home/testuser/app.log"
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" manual 1 2>&1)
+
+    # Excluded files should not exist in backup
+    assert_file_not_exists "$TEST_BACKUP_DIR/$HOSTNAME/latest/home/testuser/temp.tmp" "should exclude .tmp files" || {
+        teardown_test_env
+        return 1
+    }
+    assert_file_not_exists "$TEST_BACKUP_DIR/$HOSTNAME/latest/home/testuser/app.log" "should exclude .log files" || {
+        teardown_test_env
+        return 1
+    }
+    # Regular files should still exist
+    assert_file_exists "$TEST_BACKUP_DIR/$HOSTNAME/latest/home/testuser/file1.txt" "should include regular files" || {
+        teardown_test_env
+        return 1
+    }
+
+    teardown_test_env
+}
+
+# ------------------------------------------------------------------------------
+# Run tests
+# ------------------------------------------------------------------------------
+run_backup_tests() {
+    echo ""
+    echo "Running backup tests..."
+    echo "------------------------------------------------------------"
+
+    run_test "creates backup directory structure" test_creates_backup_structure
+    run_test "copies files to backup" test_copies_files
+    run_test "snapshot is read-only" test_snapshot_readonly
+    run_test "rotation works correctly" test_rotation
+    run_test "respects retention limit" test_retention_limit
+    run_test "backup command works as alias" test_backup_command
+    run_test "excludes files matching patterns" test_excludes_patterns
+}
+
+# Run if executed directly
+if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
+    run_backup_tests
+    print_summary
+fi
diff --git a/tests/cases/test_cron.sh b/tests/cases/test_cron.sh
new file mode 100755
index 0000000..2fdb6f5
--- /dev/null
+++ b/tests/cases/test_cron.sh
@@ -0,0 +1,138 @@
+#!/usr/bin/env bash
+# ==============================================================================
+# Cron Job Management Tests
+# ==============================================================================
+
+source "$(dirname "${BASH_SOURCE[0]}")/../lib/test_helpers.sh"
+
+# Save original crontab to restore later
+ORIGINAL_CRONTAB=""
+
+save_crontab() {
+    ORIGINAL_CRONTAB=$(crontab -l 2>/dev/null || true)
+}
+
+restore_crontab() {
+    if [ -n "$ORIGINAL_CRONTAB" ]; then
+        echo "$ORIGINAL_CRONTAB" | crontab -
+    else
+        crontab -r 2>/dev/null || true
+    fi
+}
+
+# ------------------------------------------------------------------------------
+# Test: Setup adds cron jobs
+# ------------------------------------------------------------------------------
+test_setup_adds_cron_jobs() {
+    setup_test_env
+    save_crontab
+
+    # Clear existing crontab
+    crontab -r 2>/dev/null || true
+
+    # Create minimal config
+    cat > "$TEST_CONFIG_DIR/config" << EOF
+REMOTE_HOST=""
+MOUNTDIR="$TEST_BACKUP_DIR"
+EOF
+    create_test_includes
+    create_test_excludes
+
+    # Run setup (will fail on some checks but should still add cron)
+    sudo INSTALLHOME="$TEST_CONFIG_DIR" SCRIPTLOC="/tmp/rsyncshot-test" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" setup 2>&1 >/dev/null || true
+
+    # Check crontab contains rsyncshot entries
+    local crontab_content
+    crontab_content=$(crontab -l 2>/dev/null)
+
+    restore_crontab
+    teardown_test_env
+
+    assert_contains "$crontab_content" "rsyncshot" "crontab should contain rsyncshot" || return 1
+    assert_contains "$crontab_content" "hourly" "crontab should contain hourly job" || return 1
+    assert_contains "$crontab_content" "daily" "crontab should contain daily job" || return 1
+    assert_contains "$crontab_content" "weekly" "crontab should contain weekly job" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Repeated setup doesn't duplicate entries
+# ------------------------------------------------------------------------------
+test_no_duplicate_cron_entries() {
+    setup_test_env
+    save_crontab
+
+    # Clear existing crontab
+    crontab -r 2>/dev/null || true
+
+    cat > "$TEST_CONFIG_DIR/config" << EOF
+REMOTE_HOST=""
+MOUNTDIR="$TEST_BACKUP_DIR"
+EOF
+    create_test_includes
+    create_test_excludes
+
+    # Run setup twice
+    sudo INSTALLHOME="$TEST_CONFIG_DIR" SCRIPTLOC="/tmp/rsyncshot-test" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" setup 2>&1 >/dev/null || true
+    sudo INSTALLHOME="$TEST_CONFIG_DIR" SCRIPTLOC="/tmp/rsyncshot-test" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" setup 2>&1 >/dev/null || true
+
+    # Count rsyncshot entries
+    local crontab_content hourly_count
+    crontab_content=$(crontab -l 2>/dev/null)
+    hourly_count=$(echo "$crontab_content" | grep -c "hourly" || echo 0)
+
+    restore_crontab
+    teardown_test_env
+
+    # Should only have 1 hourly entry, not 2
+    assert_equals "1" "$hourly_count" "should have exactly 1 hourly entry after repeated setup" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Setup preserves existing cron jobs
+# ------------------------------------------------------------------------------
+test_preserves_existing_cron() {
+    setup_test_env
+    save_crontab
+
+    # Add a custom cron job
+    (crontab -l 2>/dev/null || true; echo "0 5 * * * /custom/job.sh") | crontab -
+
+    cat > "$TEST_CONFIG_DIR/config" << EOF
+REMOTE_HOST=""
+MOUNTDIR="$TEST_BACKUP_DIR"
+EOF
+    create_test_includes
+    create_test_excludes
+
+    # Run setup
+    sudo INSTALLHOME="$TEST_CONFIG_DIR" SCRIPTLOC="/tmp/rsyncshot-test" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" setup 2>&1 >/dev/null || true
+
+    # Check custom job still exists
+    local crontab_content
+    crontab_content=$(crontab -l 2>/dev/null)
+
+    restore_crontab
+    teardown_test_env
+
+    assert_contains "$crontab_content" "/custom/job.sh" "should preserve existing cron jobs" || return 1
+    assert_contains "$crontab_content" "rsyncshot" "should also have rsyncshot jobs" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Run tests
+# ------------------------------------------------------------------------------
+run_cron_tests() {
+    echo ""
+    echo "Running cron tests..."
+    echo "------------------------------------------------------------"
+
+    run_test "setup adds cron jobs" test_setup_adds_cron_jobs
+    run_test "repeated setup doesn't duplicate entries" test_no_duplicate_cron_entries
+    run_test "setup preserves existing cron jobs" test_preserves_existing_cron
+}
+
+# Run if executed directly
+if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
+    run_cron_tests
+    print_summary
+fi
diff --git a/tests/cases/test_dryrun.sh b/tests/cases/test_dryrun.sh
new file mode 100755
index 0000000..bff45e1
--- /dev/null
+++ b/tests/cases/test_dryrun.sh
@@ -0,0 +1,120 @@
+#!/usr/bin/env bash
+# ==============================================================================
+# Dry-Run Mode Tests
+# ==============================================================================
+
+source "$(dirname "${BASH_SOURCE[0]}")/../lib/test_helpers.sh"
+
+# ------------------------------------------------------------------------------
+# Test: Dry-run doesn't create backup directory
+# ------------------------------------------------------------------------------
+test_dryrun_no_directory_creation() {
+    setup_test_env
+
+    create_test_config
+    create_test_includes
+    create_test_excludes
+
+    # Remove backup dir to verify it's not created
+    rmdir "$TEST_BACKUP_DIR"
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" dryrun manual 1 2>&1)
+
+    # Backup directory should NOT be created in dry-run mode
+    assert_dir_not_exists "$TEST_BACKUP_DIR/$HOSTNAME" "backup dir should not be created in dryrun" || {
+        teardown_test_env
+        return 1
+    }
+
+    teardown_test_env
+}
+
+# ------------------------------------------------------------------------------
+# Test: Dry-run shows what would be transferred
+# ------------------------------------------------------------------------------
+test_dryrun_shows_transfer_info() {
+    setup_test_env
+
+    create_test_config
+    create_test_includes
+    create_test_excludes
+
+    # Create the backup directory structure for dryrun to work
+    mkdir -p "$TEST_BACKUP_DIR/$HOSTNAME/latest"
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" dryrun manual 1 2>&1)
+
+    teardown_test_env
+
+    # Should show syncing messages
+    assert_contains "$output" "Syncing" "should show syncing info" || return 1
+    # Should show dry run message
+    assert_contains "$output" "Dry run complete" "should show dryrun complete message" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Dry-run shows command to run actual backup
+# ------------------------------------------------------------------------------
+test_dryrun_shows_actual_command() {
+    setup_test_env
+
+    create_test_config
+    create_test_includes
+    create_test_excludes
+
+    mkdir -p "$TEST_BACKUP_DIR/$HOSTNAME/latest"
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" dryrun manual 1 2>&1)
+
+    teardown_test_env
+
+    # Should show how to run actual backup
+    assert_contains "$output" "sudo rsyncshot manual 1" "should show actual command" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Dry-run doesn't create snapshots
+# ------------------------------------------------------------------------------
+test_dryrun_no_snapshot_creation() {
+    setup_test_env
+
+    create_test_config
+    create_test_includes
+    create_test_excludes
+
+    mkdir -p "$TEST_BACKUP_DIR/$HOSTNAME/latest"
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" dryrun manual 1 2>&1)
+
+    # Should not create manual.0 snapshot
+    assert_dir_not_exists "$TEST_BACKUP_DIR/$HOSTNAME/manual.0" "snapshot should not be created in dryrun" || {
+        teardown_test_env
+        return 1
+    }
+
+    teardown_test_env
+}
+
+# ------------------------------------------------------------------------------
+# Run tests
+# ------------------------------------------------------------------------------
+run_dryrun_tests() {
+    echo ""
+    echo "Running dry-run tests..."
+    echo "------------------------------------------------------------"
+
+    run_test "dry-run doesn't create backup directory" test_dryrun_no_directory_creation
+    run_test "dry-run shows transfer info" test_dryrun_shows_transfer_info
+    run_test "dry-run shows actual command" test_dryrun_shows_actual_command
+    run_test "dry-run doesn't create snapshots" test_dryrun_no_snapshot_creation
+}
+
+# Run if executed directly
+if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
+    run_dryrun_tests
+    print_summary
+fi
diff --git a/tests/cases/test_includes.sh b/tests/cases/test_includes.sh
new file mode 100755
index 0000000..8f556e3
--- /dev/null
+++ b/tests/cases/test_includes.sh
@@ -0,0 +1,161 @@
+#!/usr/bin/env bash
+# ==============================================================================
+# Include File Parsing Tests
+# ==============================================================================
+
+source "$(dirname "${BASH_SOURCE[0]}")/../lib/test_helpers.sh"
+
+# ------------------------------------------------------------------------------
+# Test: Reads newline-separated paths
+# ------------------------------------------------------------------------------
+test_reads_newline_paths() {
+    setup_test_env
+
+    # Create config and include files
+    create_test_config
+    create_test_excludes
+
+    # Create include file with newline-separated paths
+    cat > "$TEST_CONFIG_DIR/include.txt" << EOF
+$TEST_SOURCE_DIR/home
+$TEST_SOURCE_DIR/etc
+EOF
+
+    # Run dryrun to test parsing
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" dryrun manual 1 2>&1)
+    local exit_code=$?
+
+    teardown_test_env
+
+    # Should process both directories
+    assert_contains "$output" "Syncing $TEST_SOURCE_DIR/home" "should sync home" || return 1
+    assert_contains "$output" "Syncing $TEST_SOURCE_DIR/etc" "should sync etc" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Skips comment lines
+# ------------------------------------------------------------------------------
+test_skips_comments() {
+    setup_test_env
+
+    create_test_config
+    create_test_excludes
+
+    # Create include file with comments
+    cat > "$TEST_CONFIG_DIR/include.txt" << EOF
+# This is a comment
+$TEST_SOURCE_DIR/home
+# Another comment
+$TEST_SOURCE_DIR/etc
+EOF
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" dryrun manual 1 2>&1)
+
+    teardown_test_env
+
+    # Should not try to sync comment lines
+    assert_not_contains "$output" "Syncing # This" "should skip comments" || return 1
+    assert_contains "$output" "Syncing $TEST_SOURCE_DIR/home" "should sync home" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Skips empty lines
+# ------------------------------------------------------------------------------
+test_skips_empty_lines() {
+    setup_test_env
+
+    create_test_config
+    create_test_excludes
+
+    # Create include file with empty lines
+    cat > "$TEST_CONFIG_DIR/include.txt" << EOF
+$TEST_SOURCE_DIR/home
+
+$TEST_SOURCE_DIR/etc
+
+EOF
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" dryrun manual 1 2>&1)
+
+    teardown_test_env
+
+    # Should process both directories without errors
+    assert_contains "$output" "Syncing $TEST_SOURCE_DIR/home" "should sync home" || return 1
+    assert_contains "$output" "Syncing $TEST_SOURCE_DIR/etc" "should sync etc" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Handles paths with spaces
+# ------------------------------------------------------------------------------
+test_handles_paths_with_spaces() {
+    setup_test_env
+
+    create_test_config
+    create_test_excludes
+
+    # Create a directory with spaces
+    mkdir -p "$TEST_SOURCE_DIR/path with spaces"
+    echo "test" > "$TEST_SOURCE_DIR/path with spaces/file.txt"
+
+    # Create include file with path containing spaces
+    cat > "$TEST_CONFIG_DIR/include.txt" << EOF
+$TEST_SOURCE_DIR/path with spaces
+EOF
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" dryrun manual 1 2>&1)
+
+    teardown_test_env
+
+    # Should handle the path with spaces
+    assert_contains "$output" "path with spaces" "should handle spaces in path" || return 1
+    assert_not_contains "$output" "not found" "should not report path not found" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Reports missing directory
+# ------------------------------------------------------------------------------
+test_reports_missing_directory() {
+    setup_test_env
+
+    create_test_config
+    create_test_excludes
+
+    # Create include file with non-existent path
+    cat > "$TEST_CONFIG_DIR/include.txt" << EOF
+/nonexistent/path/that/does/not/exist
+EOF
+
+    local output
+    output=$(sudo INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" dryrun manual 1 2>&1)
+    local exit_code=$?
+
+    teardown_test_env
+
+    assert_exit_code 1 "$exit_code" "should fail for missing directory" || return 1
+    assert_contains "$output" "not found" "should report directory not found" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Run tests
+# ------------------------------------------------------------------------------
+run_includes_tests() {
+    echo ""
+    echo "Running include file tests..."
+    echo "------------------------------------------------------------"
+
+    run_test "reads newline-separated paths" test_reads_newline_paths
+    run_test "skips comment lines" test_skips_comments
+    run_test "skips empty lines" test_skips_empty_lines
+    run_test "handles paths with spaces" test_handles_paths_with_spaces
+    run_test "reports missing directory" test_reports_missing_directory
+}
+
+# Run if executed directly
+if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
+    run_includes_tests
+    print_summary
+fi
diff --git a/tests/cases/test_validation.sh b/tests/cases/test_validation.sh
new file mode 100755
index 0000000..03da676
--- /dev/null
+++ b/tests/cases/test_validation.sh
@@ -0,0 +1,106 @@
+#!/usr/bin/env bash
+# ==============================================================================
+# Input Validation Tests
+# ==============================================================================
+
+source "$(dirname "${BASH_SOURCE[0]}")/../lib/test_helpers.sh"
+
+# ------------------------------------------------------------------------------
+# Test: Help works without root
+# ------------------------------------------------------------------------------
+test_help_without_root() {
+    local output
+    output=$("$SCRIPT_PATH" help 2>&1)
+    local exit_code=$?
+
+    assert_exit_code 0 "$exit_code" "help should exit with 0" || return 1
+    assert_contains "$output" "rsyncshot" "help should mention rsyncshot" || return 1
+    assert_contains "$output" "Usage" "help should show usage" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Rejects non-alphabetic snapshot type
+# ------------------------------------------------------------------------------
+test_rejects_numeric_snapshot_type() {
+    local output
+    output=$(sudo "$SCRIPT_PATH" "123" "5" 2>&1)
+    local exit_code=$?
+
+    assert_exit_code 1 "$exit_code" "should reject numeric snapshot type" || return 1
+    assert_contains "$output" "must be alphabetic" "should show alphabetic error" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Rejects mixed alphanumeric snapshot type
+# ------------------------------------------------------------------------------
+test_rejects_mixed_snapshot_type() {
+    local output
+    output=$(sudo "$SCRIPT_PATH" "hourly123" "5" 2>&1)
+    local exit_code=$?
+
+    assert_exit_code 1 "$exit_code" "should reject mixed snapshot type" || return 1
+    assert_contains "$output" "must be alphabetic" "should show alphabetic error" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Rejects non-numeric retention count
+# ------------------------------------------------------------------------------
+test_rejects_alpha_retention_count() {
+    local output
+    output=$(sudo "$SCRIPT_PATH" "manual" "abc" 2>&1)
+    local exit_code=$?
+
+    assert_exit_code 1 "$exit_code" "should reject alphabetic count" || return 1
+    assert_contains "$output" "must be a number" "should show number error" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Rejects mixed alphanumeric retention count
+# ------------------------------------------------------------------------------
+test_rejects_mixed_retention_count() {
+    local output
+    output=$(sudo "$SCRIPT_PATH" "manual" "5abc" 2>&1)
+    local exit_code=$?
+
+    assert_exit_code 1 "$exit_code" "should reject mixed count" || return 1
+    assert_contains "$output" "must be a number" "should show number error" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Test: Accepts valid alphabetic snapshot types
+# ------------------------------------------------------------------------------
+test_accepts_valid_snapshot_types() {
+    # We use dryrun to avoid actual backup, and expect it to fail on missing config
+    # but it should get past the validation stage
+    local output
+    output=$(sudo "$SCRIPT_PATH" dryrun "hourly" "24" 2>&1)
+
+    # Should not contain the validation error (might fail for other reasons like missing config)
+    assert_not_contains "$output" "must be alphabetic" "should accept valid type" || return 1
+}
+
+# ------------------------------------------------------------------------------
+# Run tests
+# ------------------------------------------------------------------------------
+run_validation_tests() {
+    echo ""
+    echo "Running validation tests..."
+    echo "------------------------------------------------------------"
+
+    setup_test_env
+
+    run_test "help works without root" test_help_without_root
+    run_test "rejects numeric snapshot type" test_rejects_numeric_snapshot_type
+    run_test "rejects mixed alphanumeric snapshot type" test_rejects_mixed_snapshot_type
+    run_test "rejects alphabetic retention count" test_rejects_alpha_retention_count
+    run_test "rejects mixed retention count" test_rejects_mixed_retention_count
+    run_test "accepts valid snapshot types" test_accepts_valid_snapshot_types
+
+    teardown_test_env
+}
+
+# Run if executed directly
+if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
+    run_validation_tests
+    print_summary
+fi
diff --git a/tests/lib/test_helpers.sh b/tests/lib/test_helpers.sh
new file mode 100755
index 0000000..726d788
--- /dev/null
+++ b/tests/lib/test_helpers.sh
@@ -0,0 +1,247 @@
+#!/usr/bin/env bash
+# ==============================================================================
+# Test Helper Functions for rsyncshot
+# ==============================================================================
+
+# Colors for output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[0;33m'
+NC='\033[0m' # No Color
+
+# Counters
+TESTS_RUN=0
+TESTS_PASSED=0
+TESTS_FAILED=0
+
+# Test environment paths
+TEST_DIR=""
+TEST_CONFIG_DIR=""
+TEST_BACKUP_DIR=""
+SCRIPT_PATH=""
+
+# ------------------------------------------------------------------------------
+# Setup/Teardown
+# ------------------------------------------------------------------------------
+
+setup_test_env() {
+    # Create temporary directories for testing
+    TEST_DIR=$(mktemp -d)
+    TEST_CONFIG_DIR="$TEST_DIR/etc/rsyncshot"
+    TEST_BACKUP_DIR="$TEST_DIR/backup"
+    TEST_SOURCE_DIR="$TEST_DIR/source"
+
+    mkdir -p "$TEST_CONFIG_DIR"
+    mkdir -p "$TEST_BACKUP_DIR"
+    mkdir -p "$TEST_SOURCE_DIR/home/testuser"
+    mkdir -p "$TEST_SOURCE_DIR/etc"
+
+    # Create some test files
+    echo "test file 1" > "$TEST_SOURCE_DIR/home/testuser/file1.txt"
+    echo "test file 2" > "$TEST_SOURCE_DIR/home/testuser/file2.txt"
+    echo "config data" > "$TEST_SOURCE_DIR/etc/test.conf"
+
+    # Find the script (relative to tests directory)
+    SCRIPT_PATH="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)/rsyncshot"
+
+    if [ ! -f "$SCRIPT_PATH" ]; then
+        echo "ERROR: Cannot find rsyncshot script at $SCRIPT_PATH"
+        exit 1
+    fi
+}
+
+teardown_test_env() {
+    # Clean up temporary directories
+    if [ -n "$TEST_DIR" ] && [ -d "$TEST_DIR" ]; then
+        rm -rf "$TEST_DIR"
+    fi
+}
+
+# Run rsyncshot with test environment variables
+# Usage: run_rsyncshot [args...]
+run_rsyncshot() {
+    INSTALLHOME="$TEST_CONFIG_DIR" RSYNCSHOT_SKIP_MOUNT_CHECK=1 "$SCRIPT_PATH" "$@"
+}
+
+# Create a test config file
+create_test_config() {
+    local config_file="$TEST_CONFIG_DIR/config"
+    cat > "$config_file" << EOF
+REMOTE_HOST=""
+MOUNTDIR="$TEST_BACKUP_DIR"
+EOF
+    echo "$config_file"
+}
+
+# Create a test include file
+create_test_includes() {
+    local include_file="$TEST_CONFIG_DIR/include.txt"
+    cat > "$include_file" << EOF
+$TEST_SOURCE_DIR/home
+$TEST_SOURCE_DIR/etc
+EOF
+    echo "$include_file"
+}
+
+# Create a test exclude file
+create_test_excludes() {
+    local exclude_file="$TEST_CONFIG_DIR/exclude.txt"
+    cat > "$exclude_file" << EOF
+*.tmp
+*.log
+.cache
+EOF
+    echo "$exclude_file"
+}
+
+# ------------------------------------------------------------------------------
+# Assertions
+# ------------------------------------------------------------------------------
+
+assert_equals() {
+    local expected="$1"
+    local actual="$2"
+    local message="${3:-Values should be equal}"
+
+    if [ "$expected" = "$actual" ]; then
+        return 0
+    else
+        echo -e "${RED}FAIL${NC}: $message"
+        echo "  Expected: $expected"
+        echo "  Actual:   $actual"
+        return 1
+    fi
+}
+
+assert_exit_code() {
+    local expected="$1"
+    local actual="$2"
+    local message="${3:-Exit code should be $expected}"
+
+    if [ "$expected" -eq "$actual" ]; then
+        return 0
+    else
+        echo -e "${RED}FAIL${NC}: $message"
+        echo "  Expected exit code: $expected"
+        echo "  Actual exit code:   $actual"
+        return 1
+    fi
+}
+
+assert_contains() {
+    local haystack="$1"
+    local needle="$2"
+    local message="${3:-Output should contain '$needle'}"
+
+    if echo "$haystack" | grep -q "$needle"; then
+        return 0
+    else
+        echo -e "${RED}FAIL${NC}: $message"
+        echo "  Looking for: $needle"
+        echo "  In output:   $haystack"
+        return 1
+    fi
+}
+
+assert_not_contains() {
+    local haystack="$1"
+    local needle="$2"
+    local message="${3:-Output should not contain '$needle'}"
+
+    if ! echo "$haystack" | grep -q "$needle"; then
+        return 0
+    else
+        echo -e "${RED}FAIL${NC}: $message"
+        echo "  Should not contain: $needle"
+        echo "  But found in:       $haystack"
+        return 1
+    fi
+}
+
+assert_file_exists() {
+    local file="$1"
+    local message="${2:-File should exist: $file}"
+
+    if [ -f "$file" ]; then
+        return 0
+    else
+        echo -e "${RED}FAIL${NC}: $message"
+        return 1
+    fi
+}
+
+assert_dir_exists() {
+    local dir="$1"
+    local message="${2:-Directory should exist: $dir}"
+
+    if [ -d "$dir" ]; then
+        return 0
+    else
+        echo -e "${RED}FAIL${NC}: $message"
+        return 1
+    fi
+}
+
+assert_file_not_exists() {
+    local file="$1"
+    local message="${2:-File should not exist: $file}"
+
+    if [ ! -f "$file" ]; then
+        return 0
+    else
+        echo -e "${RED}FAIL${NC}: $message"
+        return 1
+    fi
+}
+
+assert_dir_not_exists() {
+    local dir="$1"
+    local message="${2:-Directory should not exist: $dir}"
+
+    if [ ! -d "$dir" ]; then
+        return 0
+    else
+        echo -e "${RED}FAIL${NC}: $message"
+        return 1
+    fi
+}
+
+# ------------------------------------------------------------------------------
+# Test Runner
+# ------------------------------------------------------------------------------
+
+run_test() {
+    local test_name="$1"
+    local test_func="$2"
+
+    TESTS_RUN=$((TESTS_RUN + 1))
+
+    # Run the test function and capture result
+    if $test_func; then
+        echo -e "${GREEN}PASS${NC}: $test_name"
+        TESTS_PASSED=$((TESTS_PASSED + 1))
+        return 0
+    else
+        TESTS_FAILED=$((TESTS_FAILED + 1))
+        return 1
+    fi
+}
+
+print_summary() {
+    echo ""
+    echo "============================================================"
+    echo "Test Summary"
+    echo "============================================================"
+    echo -e "Total:  $TESTS_RUN"
+    echo -e "Passed: ${GREEN}$TESTS_PASSED${NC}"
+    echo -e "Failed: ${RED}$TESTS_FAILED${NC}"
+    echo ""
+
+    if [ "$TESTS_FAILED" -eq 0 ]; then
+        echo -e "${GREEN}All tests passed!${NC}"
+        return 0
+    else
+        echo -e "${RED}Some tests failed.${NC}"
+        return 1
+    fi
+}
diff --git a/tests/test_rsyncshot.sh b/tests/test_rsyncshot.sh
new file mode 100755
index 0000000..15f2a99
--- /dev/null
+++ b/tests/test_rsyncshot.sh
@@ -0,0 +1,120 @@
+#!/usr/bin/env bash
+# ==============================================================================
+# rsyncshot Test Suite
+# ==============================================================================
+#
+# Runs all automated tests for rsyncshot.
+#
+# Usage:
+#   sudo ./tests/test_rsyncshot.sh           # Run all tests
+#   sudo ./tests/test_rsyncshot.sh -v        # Verbose output
+#   sudo ./tests/test_rsyncshot.sh --quick   # Skip slow tests
+#
+# ==============================================================================
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+VERBOSE=false
+QUICK=false
+
+# Parse arguments
+while [[ $# -gt 0 ]]; do
+    case $1 in
+        -v|--verbose)
+            VERBOSE=true
+            shift
+            ;;
+        -q|--quick)
+            QUICK=true
+            shift
+            ;;
+        -h|--help)
+            echo "Usage: $0 [-v|--verbose] [-q|--quick]"
+            echo ""
+            echo "Options:"
+            echo "  -v, --verbose  Show detailed test output"
+            echo "  -q, --quick    Skip slow tests (backup/rotation)"
+            exit 0
+            ;;
+        *)
+            echo "Unknown option: $1"
+            exit 1
+            ;;
+    esac
+done
+
+# Check for root
+if [ "$EUID" -ne 0 ]; then
+    echo "Tests must be run as root (sudo ./tests/test_rsyncshot.sh)"
+    exit 1
+fi
+
+# Source test helpers
+source "$SCRIPT_DIR/lib/test_helpers.sh"
+
+echo "============================================================"
+echo "rsyncshot Test Suite"
+echo "============================================================"
+echo ""
+echo "Script: $(cd "$SCRIPT_DIR/.." && pwd)/rsyncshot"
+echo "Date:   $(date)"
+echo ""
+
+# Track overall results
+TOTAL_RUN=0
+TOTAL_PASSED=0
+TOTAL_FAILED=0
+
+# Run a test file and accumulate results
+run_test_file() {
+    local test_file="$1"
+    local test_name="$2"
+
+    # Reset counters before sourcing
+    TESTS_RUN=0
+    TESTS_PASSED=0
+    TESTS_FAILED=0
+
+    # Source and run the test file
+    source "$test_file"
+
+    # Call the run function
+    "run_${test_name}_tests"
+
+    # Accumulate totals
+    TOTAL_RUN=$((TOTAL_RUN + TESTS_RUN))
+    TOTAL_PASSED=$((TOTAL_PASSED + TESTS_PASSED))
+    TOTAL_FAILED=$((TOTAL_FAILED + TESTS_FAILED))
+}
+
+# Run test suites
+run_test_file "$SCRIPT_DIR/cases/test_validation.sh" "validation"
+run_test_file "$SCRIPT_DIR/cases/test_includes.sh" "includes"
+run_test_file "$SCRIPT_DIR/cases/test_dryrun.sh" "dryrun"
+
+if [ "$QUICK" = false ]; then
+    run_test_file "$SCRIPT_DIR/cases/test_backup.sh" "backup"
+    run_test_file "$SCRIPT_DIR/cases/test_cron.sh" "cron"
+else
+    echo ""
+    echo "Skipping slow tests (backup, cron) - use without --quick to run all"
+fi
+
+# Print final summary
+echo ""
+echo "============================================================"
+echo "Final Summary"
+echo "============================================================"
+echo -e "Total:  $TOTAL_RUN"
+echo -e "Passed: ${GREEN}$TOTAL_PASSED${NC}"
+echo -e "Failed: ${RED}$TOTAL_FAILED${NC}"
+echo ""
+
+if [ "$TOTAL_FAILED" -eq 0 ]; then
+    echo -e "${GREEN}All tests passed!${NC}"
+    exit 0
+else
+    echo -e "${RED}Some tests failed.${NC}"
+    exit 1
+fi
diff --git a/todo.org b/todo.org
deleted file mode 100644
index e2a1374..0000000
--- a/todo.org
+++ /dev/null
@@ -1,73 +0,0 @@
-* Rsyncshot Open Work
-** [#B] crontab should offer more schedules
-*** 2024-05-06 Mon @ 15:51:58 -0500 problem to solve
-currently, rsyncshot has the following
-hourly each day
-daily each week
-every week
-
-...and that's it. Of course, the user can fiddle with this as they please to achieve any backup schedule they desire. However, most users won't want to mess with cron.
-
-We should do it for them. Here's what I suspect these two will be the most common:
-
-DATE BOUND
-- hourly, expiring past a specific date period (e.g., month or year)
-- daily, expiring past a specific date period  (e.g., month or year)
-- every X minutes, expiring past a specific date period  (e.g., month or year)
-
-STAGGERED
-- every 10 mins for the hour (max 5, as the last will be the hourly)
-- every hour for the day (max 23, as the last will be daily)
-- every day for the week (max 6 as, the last will be weekly)
-- every week for the year (max 51 as, the last will be yearly)
-- every year (ongoing)
-
-This means that a full year will have 86 backups.
-The user can choose to not do the 10 min or hourly backups and just allow for day, week, year.
-** [#B] backup pruning should be more robust
-*** 2024-05-06 Mon @ 16:21:29 -0500 problem to solve
-if the user uses a
-use awk to identify files outside of range and delete via loop
-** [#C] strip - and -- to ease users finding help/usage options
-*** 2024-05-06 Mon @ 15:31:50 -0500 problem to solve
-The user may not know how to even get help on the command line
-typical command line arguments are --help -h and others.
-let's make it easy for the user by stripping off the
-** [#C] help should be able to tell more about environment and act on it
-*** 2024-05-06 Mon @ 15:34:10 -0500 problem to solve
-is there a drive mounted on /media/backup (or the default location)?
-has rsyncshot been installed?
-have the cron jobs been set up?
-
-instructions should then change based on install state
-- if not installed, setup instructions are clear
-- if installed, install and log location is clear
-- if installed but no cron jobs, tell user how to set them up, offer to set up dailies, etc.
-- if no drive mounted, give user the command line option or offer to mount the drive
-
-You could tackle this in pieces: installation check, cron job check, mounted drive check, etc.
-** [#C] backup drive should have an optional command line argument
-*** 2024-05-06 Mon @ 15:47:56 -0500 problem to solve
-reason: users may want to backup to a different directory via crontab or manually
-default exists now (i.e., "/media/backup")
-changing it means changing the source
-
-we should allow the user to pass -d (for destination) with a path
-- validate the path exists
-- assigning the destination
-** [#C] ability to trigger immediate backup
-*** 2024-05-06 Mon @ 16:21:53 -0500 problem to solve
-the user has to wait for the cron job to kick off for a backup
-however, they may want to manually trigger a backup immediately
-they can do this by: "rsyncshot <some-random-name> <some-random-number>
-
-however, we should make it easier for them.
-options:
-- no command line arguments issues the equivalent of rsyncshot BACKUP 100
-  the downside here is that the user may expect this to be a way to get usage information.
-- a command line option like: "rsyncshot --backup-now"
-  it's not obvious what to choose for the switch.
-  what have other authors chosen for an option in similar situations?
-
-* Rsyncshot Resolved
-** DONE [#B] backups should be contained in a subdirectory based on hostname