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

I am personally defining a require target which runs before all the others. This target simply runs the version commands of all requirements one at a time and prints appropriate error messages if the command is invalid.

all: require validate test etc

require:
    @echo "Checking the programs required for the build are installed..."
    @shellcheck --version >/dev/null 2>&1 || (echo "ERROR: shellcheck is required."; exit 1)
    @derplerp --version >/dev/null 2>&1 || (echo "ERROR: derplerp is required."; exit 1) 

# And the rest of your makefile below.

The output of the below script is

Checking the programs required for the build are installed...
ERROR: derplerp is required.
makefile:X: recipe for target 'prerequisites' failed
make: *** [prerequisites] Error 1