My Notes on Makefiles

April 16, 2021 - Reading time: 3 minutes

Stuff I use most

Output Functions

• $(info ...) - Print out some info message
• $(warning ...) - Print out a warning
• $(error ...) - Print out an error and STOP

Defines

• D = something - Set D equal to 'something' every time D is used (expand every time)
• D := something - Set D equal to 'something' once (expand only once. non-recursive)
• D ?= something - Set D equal to 'something' only if not already set

Functions

• $(shell ) - Run 'command' in a shell and return output

• $(call var,arg,arg,...) - Call a function, var, with args.

  call example call example: reverse = $(2) $(1) D = $(call reverse,a,b) # D will contain 'b a'

• $(filter pat,text) - Filter 'text' by 'pat'

  filter example filter example: D = a.h a.c b.h b.c CFiles = $(filter %.c,$(D)) # CFiles will contain 'a.c b.c' only

• $(if ,,) - If 'cond' is non-empty string, do 'then'...

• $(or arg,arg,...) - Return first non-empty arg or empty string

• $(and arg,arg,...) - Return empty string or last non-empty arg

List Functions

• $(sort ) - Sort list
• $(firstword list) - Return first item in space-separated list
• $(lastword list) - Return last item in space-separated list
• $(word nth,list) - Return 1-based nth word in list
• $(words list) - Return the number of words in space-separated list
• $(wordlist start,end,list) - Return words from start to end in list

Directory/Path/File Functions

• $(abspath ...) - Get absolute path of a file and don't check for existence
• $(realpath ...) - Get real path of a file and return empty string if it doesn't exist
• $(wildcard ) - Get list of files matching 'pattern'

Create/Append to File

• $(file >$(log),stuff) - Write 'stuff' to log file

More stuff