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(autoconf.info)Generic Programs

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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 (Note: 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, Note: 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 exists on the `PATH'.  If it 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 (Note: Canonicalizing).  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 (Note:
     Canonicalizing). 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.