What do $@ and $< in a makefile mean

make

I am seeing a makefile and it has the symbols $@ and $< in it. I have never seen them, and Google does not show any results about them. Do you know what these commands do?

Best Answer

From make manpage:

$@ is:

The file name of the target of the rule. If the target is an archive member, then ‘$@’ is the name of the archive file. In a pattern rule that has multiple targets (see Introduction to Pattern Rules), ‘$@’ is the name of whichever target caused the rule's recipe to be run.

$< is:

The name of the first prerequisite. If the target got its recipe from an implicit rule, this will be the first prerequisite added by the implicit rule.

You can see complete manual here.

Related Solutions

Output to multiple files with Makefile

Try this:

TEX = pandoc
MEXT = md
SRC = $(wildcard *.$(MEXT))
PDFS = $(SRC:.md=.pdf)
TMP = template.tex
FLAGS = --latex-engine=xelatex

all:    ${PDFS}

%.pdf:  %.md ${TMP}
        ${TEX} $(filter-out $<,$^ ) -o $@ --template=${TMP} $(FLAGS) $<


.PHONY: clean
clean:
        rm *.pdf

Bash – What does “-” mean in this “-cp” command

- in a recipe tells Make to ignore any errors (see Errors in recipes).

In this specific case, any error reported by cp will be ignored (the output will contain any messages, but the build will continue).

This only works if - is interpreted by Make, i.e. it's the first non-whitespace character in the line (or the characters preceding it are also interpreted by Make). In this case, $(hide) needs to be considered: if hide is empty or @, -cp will have the intended effect; but if hide is for instance @>/dev/null (so the command isn't echoed and its standard output is discarded), -cp will be passed as-is to the shell and the command will fail.

Best Answer

Related Solutions

Output to multiple files with Makefile

Bash – What does “-” mean in this “-cp” command

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