From 754bbf7a25a8dda49b5d08ef0d0443bbf5af0e36 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Sun, 7 Apr 2024 13:41:34 -0500 Subject: new repository --- devdocs/gnu_make/override-directive.html | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) create mode 100644 devdocs/gnu_make/override-directive.html (limited to 'devdocs/gnu_make/override-directive.html') diff --git a/devdocs/gnu_make/override-directive.html b/devdocs/gnu_make/override-directive.html new file mode 100644 index 00000000..bcf6d42e --- /dev/null +++ b/devdocs/gnu_make/override-directive.html @@ -0,0 +1,18 @@ +

The override Directive

If a variable has been set with a command argument (see Overriding Variables), then ordinary assignments in the makefile are ignored. If you want to set the variable in the makefile even though it was set with a command argument, you can use an override directive, which is a line that looks like this: 

override variable = value
+
+

or 

override variable := value
+
+

To append more text to a variable defined on the command line, use: 

override variable += more text
+
+

See Appending More Text to Variables.

Variable assignments marked with the override flag have a higher priority than all other assignments, except another override. Subsequent assignments or appends to this variable which are not marked override will be ignored.

The override directive was not invented for escalation in the war between makefiles and command arguments. It was invented so you can alter and add to values that the user specifies with command arguments.

For example, suppose you always want the ‘-g’ switch when you run the C compiler, but you would like to allow the user to specify the other switches with a command argument just as usual. You could use this override directive: 

override CFLAGS += -g
+
+

You can also use override directives with define directives. This is done as you might expect: 

override define foo =
+bar
+endef
+
+

See Defining Multi-Line Variables.

+

+ Copyright © 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022 Free Software Foundation, Inc.
Licensed under the GNU Free Documentation License.
+ https://www.gnu.org/software/make/manual/html_node/Override-Directive.html +

+
-- cgit v1.2.3