#+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
# 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

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
# 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

* 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
SSH_IDENTITY_FILE="/home/youruser/.ssh/id_ed25519"
#+end_src

*** 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
# Comments start with #
#+end_src

** What Gets Excluded

Edit =/etc/rsyncshot/exclude.txt= - one pattern per line:

#+begin_src
# Caches and temp files
.cache
*.tmp
*.log

# Build artifacts
node_modules
__pycache__
*.pyc
#+end_src

* 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.