How to run a bash script from a Makefile?

Question

I have a Makefile from which I want to call another external bash script to do another part of the building. How would I best go about doing this?

Answer 1

Just like calling any other command from a makefile:

target: prerequisites
    shell_script arg1 arg2 arg3

Regarding your further explanation:

.PHONY: do_script

do_script: 
    shell_script arg1 arg2 arg3

prerequisites: do_script

target: prerequisites 

Answer 2

Perhaps not the "right" way to do it like the answers already provided, but I came across this question because I wanted my makefile to run a script I wrote to generate a header file that would provide the version for a whole package of software. I have quite a bit of targets in this package, and didn't want to add a brand new prerequisite to them all. Putting this towards the beginning of my makefile worked for me

$(shell ./genVer.sh)

which tells make to simply run a shell command. ./genVer.sh is the path (same directory as the makefile) and name of my script to run. This runs no matter which target I specify (including clean, which is the downside, but ultimately not a huge deal to me).

Answer 3

Each of the actions in the makefile rule is a command that will be executed in a subshell. You need to ensure that each command is independent, since each one will be run inside a separate subshell.

For this reason, you will often see line breaks escaped when the author wants several commands to run in the same subshell:

targetfoo:
        command_the_first foo bar baz
        command_the_second wibble wobble warble
        command_the_third which is rather too long \
            to fit on a single line so \
            intervening line breaks are escaped
        command_the_fourth spam eggs beans