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How to use shell commands in makefile Stack Overflow?
However, each line is run by a separate shell, so this variable will not survive to the next line, so you must then use it immediately: This is all a bit silly since the shell will expand * (and other shell glob expressions) for you in the first place, so you can just:
How to assign a makefile variable to a command result?
I’m trying to assign the output of this command ( that is in my makefile ) to the makefile HEADER var like in this following line of code: And if I run this command directly in the console, and directly where my makefile is:
What’s the assignment for the right hand side of Makefile?
Also, in addition to torek’s answer: one thing that stands out is that you’re using a lazily-evaluated macro assignment. If you’re on GNU Make, use the := assignment instead of =. This assignment causes the right hand side to be expanded immediately, and stored in the left hand variable.
What does it mean to use shell in make job?
If you use the = assignment, it means that every single occurrence of $ (FILES) will be expanding the $ (shell …) syntax and thus invoking the shell command. This will make your make job run slower, or even have some surprising consequences.
Can a multi line shell script be used inside make?
Multi line shell scripts may be used inside make by a backslash newline sequence in the make files. The performance argument does not apply to modern make implementations since modern implementations try to avoid to call the shell in case that the command line does not contain shell specific meta characters.
Why does making.oneshell break older makefiles?
Making .ONESHELL the default behaviour in make would potentially break older Makefiles. Even though this is not a question relating to the POSIX standard or the compliance to that standard by GNU make, the Rationale of the POSIX specification for make has this to say about the issue at hand:
What can a makefile be used to control?
You can use a makefile to control any kind of procedure where you need to selectively execute certain commands depending on which files have changed. You could, for example, use makepp to do data analysis, where your input files are raw data and analysis programs, and your output files are processed data or graphs or whatever.