5.2.2 Generic Program and File Checks

These macros are used to find programs not covered by the "particular" test macros. If you need to check the behavior of a program as well as find out whether it is present, you have to write your own test for it (see section 6. Writing Tests). By default, these macros use the environment variable PATH. If you need to check for a program that might not be in the user's PATH, you can pass a modified path to use instead, like this:

AC_PATH_PROG([INETD], [inetd], [/usr/libexec/inetd], [$PATH:/usr/libexec:/usr/sbin:/usr/etc:etc])

You are strongly encouraged to declare the variable passed to AC_CHECK_PROG etc. as precious, See section 7.2 Setting Output Variables, AC_ARG_VAR, for more details.

Macro: AC_CHECK_PROG (variable, prog-to-check-for, value-if-found, [value-if-not-found], [path], [reject])

Check whether program prog-to-check-for exists in PATH. If it is found, set variable to value-if-found, otherwise to value-if-not-found, if given. Always pass over reject (an absolute file name) even if it is the first found in the search path; in that case, set variable using the absolute file name of the prog-to-check-for found that is not reject. If variable was already set, do nothing. Calls AC_SUBST for variable.

Macro: AC_CHECK_PROGS (variable, progs-to-check-for, [value-if-not-found], [path])

Check for each program in the whitespace-separated list progs-to-check-for existing in the PATH. If one is found, set variable to the name of that program. Otherwise, continue checking the next program in the list. If none of the programs in the list are found, set variable to value-if-not-found; if value-if-not-found is not specified, the value of variable is not changed. Calls AC_SUBST for variable.

Macro: AC_CHECK_TOOL (variable, prog-to-check-for, [value-if-not-found], [path])

Like AC_CHECK_PROG, but first looks for prog-to-check-for with a prefix of the host type as determined by AC_CANONICAL_HOST, followed by a dash (see section 11.2 Getting the Canonical System Type). For example, if the user runs `configure --host=i386-gnu', then this call:

AC_CHECK_TOOL(RANLIB, ranlib, :)

sets RANLIB to `i386-gnu-ranlib' if that program exists in PATH, or otherwise to `ranlib' if that program exists in PATH, or to `:' if neither program exists.

Macro: AC_CHECK_TOOLS (variable, progs-to-check-for, [value-if-not-found], [path])

Like AC_CHECK_TOOL, each of the tools in the list progs-to-check-for are checked with a prefix of the host type as determined by AC_CANONICAL_HOST, followed by a dash (see section 11.2 Getting the Canonical System Type). If none of the tools can be found with a prefix, then the first one without a prefix is used. If a tool is found, set variable to the name of that program. If none of the tools in the list are found, set variable to value-if-not-found; if value-if-not-found is not specified, the value of variable is not changed. Calls AC_SUBST for variable.

Macro: AC_PATH_PROG (variable, prog-to-check-for, [value-if-not-found], [path])

Like AC_CHECK_PROG, but set variable to the entire path of prog-to-check-for if found.

Macro: AC_PATH_PROGS (variable, progs-to-check-for, [value-if-not-found], [path])

Like AC_CHECK_PROGS, but if any of progs-to-check-for are found, set variable to the entire path of the program found.

Macro: AC_PATH_TOOL (variable, prog-to-check-for, [value-if-not-found], [path])

Like AC_CHECK_TOOL, but set variable to the entire path of the program if it is found.