What does @[arguments] mean in a makefile?

Question

What does the @[arguments] syntax in a makefile mean? For example, I have come across a makefile that contains the following:

all: $(EXEC_NAME)
   @[ -p video_fifo ] || mkfifo video_fifo

What does this do?

Answer 1

Nothing. You are parsing it incorrectly.

The leading @ is for make. It means "silence this command". See Recipe Echoing in the GNU make manual.

The rest of the line is a shell script. In this case it starts with a test [ -p video_fifo ] (you often see this in the context of an if statement if [ -n "$var" ] or whatever see the bash manual for more about [ / test and for the -p flag) and then || mkfifo video_fifo || mkfifo video_fifo to create the video_fifo fifo if the [ test returns false (hence the || OR operator).