Calling `command -v find` from GNU Makefile

问题

I use a shell (bash, but I need portability) and a GNU Makefile. I have this code:

check_commands:
        command -v find >/dev/null
        command -v asdf >/dev/null

As supposed, the first command is passed, the second aborts the Makefile with an error. Now, I remove the >/dev/null. Why does then

check_commands:
        command -v find

produce the following error?

make: command: Command not found.

回答1:

Judging from a quick look at job.c in GNU make's sources, it attempts to avoid launching a shell when it can, i.e. when the command line is simple enough (of the form cmd args, without redirection, compound commands, etc.) and the shell is the default one. The issue is then that command is a built-in and does not have an associated executable, hence the error message from make. It does not occur when you have > /dev/null as make considers the command as too complicated and leaves it to sh to launch it.

来源：https://stackoverflow.com/questions/12989869/calling-command-v-find-from-gnu-makefile