Autoconf check for program and fail if not found

Question

I\'m creating a project and using GNU Autoconf tools to do the configuring and making. I\'ve set up all my library checking and header file checking but can\'t seem to figure ou

Answer 1

This is not exactly a short approach, it's rather a general purporse approach (although when there are dozens of programs to check it might be also the shortest approach). It's taken from a project of mine (the prefix NA_ stands for “Not Autotools”).

A general purpose macro

dnl  ***************************************************************************
dnl  NA_REQ_PROGS(prog1, [descr1][, prog2, [descr2][, etc., [...]]])
dnl
dnl  Checks whether one or more programs have been provided by the user or can
dnl  be retrieved automatically. For each program `progx` an uppercase variable
dnl  named `PROGX` containing the path where `progx` is located will be created.
dnl  If a program is not reachable and the user has not provided any path for it
dnl  an error will be generated. The program names given to this function will
dnl  be advertised among the `influential environment variables` visible when
dnl  launching `./configure --help`.
dnl  ***************************************************************************
AC_DEFUN([NA_REQ_PROGS], [
    m4_if([$#], [0], [], [
        AC_ARG_VAR(m4_translit([$1], [a-z], [A-Z]), [$2])
        AS_IF([test "x@S|@{]m4_translit([$1], [a-z], [A-Z])[}" = x], [
            AC_PATH_PROG(m4_translit([$1], [a-z], [A-Z]), [$1])
            AS_IF([test "x@S|@{]m4_translit([$1], [a-z], [A-Z])[}" = x], [
                AC_MSG_ERROR([$1 utility not found])
            ])
        ])
        m4_if(m4_eval([$# + 1 >> 1]), [1], [], [NA_REQ_PROGS(m4_shift2($*))])
    ])
])

Sample usage

NA_REQ_PROGS(
    [find],             [Unix find utility],
    [xargs],            [Unix xargs utility],
    [customprogram],    [Some custom program],
    [etcetera],         [Et cetera]
)

So that within Makefile.am you can do

$(XARGS)

or

$(CUSTOMPROGRAM)

and so on.

Features

• It advertises the programs among the “influential environment variables” visible when the final user launches ./configure --help, so that an alternative path to the program can be provided
• A bash variable named with the same name of the program, but upper case, containing the path where the program is located, is created
• En error is thrown if any of the programs given have not been found and the user has not provided any alternative path for them
• The macro can take infinite (couples of) arguments

When you should use it

1. When the programs to be tested are vital for compiling your project, so that the user must be able to provide an alternative path for them and an error must be thrown if at least one program is not available at all
2. When condition #1 applies to more than one single program, in which case there is no need to write a general purpose macro and you should just use your own customized code