Command-Replacement Macro References

If you supply a shell command as the definition of a macro:

COMMAND= cat Listfile

you can use a command-replacement macro reference to instruct make to replace the reference with the output of the command in the macro's value. This form of command substitution can occur anywhere within a makefile:

COMMAND= cat Listfile 
$(COMMAND:sh): $$(@:=.c)

This example imports a list of targets from another file and indicates that each target depends on a corresponding .c file.

As with shell command substitution, a command replacement reference evaluates to the standard output of the command. NEWLINE characters are converted to SPACE characters. The command is performed whenever the reference is encountered. The command's standard error is ignored. However, if the command returns a non-zero exit status, make halts with an error.

A workaround for this is to append the true command to the command line:

COMMAND = cat Listfile ; true