Re: How to exit if program is not found

[Timothy Madden]

On 06/14/2012 07:37 PM, Timothy Madden wrote:
> On 06/14/2012 07:07 PM, Roger Pau Monné wrote:
> > On Thu, Jun 14, 2012 at 5:01 PM, Timothy
> > Madden<address@hidden> wrote:
> > > Hello
> > >
> > > I see in the info pages that autoconf macros check for various
> > > programs and
> > > set a variable if found, but how do I get the behaviour I see in most
> > > configure programs to exit with an error if a program is not found ?
> >
> > I usually use the following macro:
> >
> > AC_DEFUN([AX_PATH_PROG_OR_FAIL],
> > [AC_PATH_PROG([$1], [$2], [no])
> > if test x"${$1}" == x"no"
> > then
> > AC_MSG_ERROR([Unable to find $2, please install $2])
> > fi])
> >
> > So on my configure.ac I make the following calls:
> >
> > AX_PATH_PROG_OR_FAIL([PERL], [perl])
> >
> > Where "PERL" is the name of the variable where to store the path, and
> > "perl" is the name of the program to search for.
>
> How about the predefined programs ?
>
> AC_PROG_YACC might set YACC to 'bison -y', how would I check that 'bison
> -y' is found or is on path ?

I find that the following command
        command -v bison -y
works as expected and returns 0 if bison is found or non-zero if there 
is no bison.

What do you know about the portability of `command` ? Can I use it in my 
configure.ac ?

Or is there a better way to exit after AC_PROG_YACC if bison is not 
found ? Or to exit if AC_PROG_CXX does not find a C++ compiler ?

> And really, is there no support in autoconf itself for this ?

Is there no flag or option to make the resulting configure exit 
automatically if any of the checks fail ?

Thank you,
Timothy Madden