Check if a program exists from a Makefile

Question

How can I check if a program is callable from a Makefile?

(That is, the program should exist in the path or otherwise be callable.)

It could be used to chec

Answer 1

My solution involves a little helper script¹ that places a flag file if all required commands exist. This comes with the advantage that the check for the required commands is only done once and not on every make invocation.

check_cmds.sh

#!/bin/bash

NEEDED_COMMANDS="jlex byaccj ant javac"

for cmd in ${NEEDED_COMMANDS} ; do
    if ! command -v ${cmd} &> /dev/null ; then
        echo Please install ${cmd}!
        exit 1
    fi
done

touch .cmd_ok

Makefile

.cmd_ok:
    ./check_cmds.sh

build: .cmd_ok target1 target2

¹ More about the command -v technique can be found here.