ac_very_nice

A macro to check the options of nice, in order to have a VERY_NICE variable which runs a program at the lowest priority VERY_NICE is undefined if we don't find the proper options, so you can safely use:

   @VERY_NICE@ mycommand

in a shell script.

The VERY_NICE variable includes the placeholder NICE_VALUE that you have to instantiate at run-time. If you give a argument to AC_VERY_NICE, it will be used as an argument of nice for testing and included in VERY_NICE instead of the above placeholder.

AC_DEFUN([AC_VERY_NICE],[
if test "x$1" != "x"; then
  NICE_VALUE=$1
else
  NICE_VALUE=20
fi
AC_CHECK_PROGS(TEST_NICE, date)
AC_CHECK_PROGS(NICE, nice, )
AC_MSG_CHECKING(syntax of nice)
if test "x$NICE" != "x"; then
     if  ( $NICE -n $NICE_VALUE $TEST_NICE > /dev/null 2>&1 ) ;  then
        VERY_NICE="$NICE -n $NICE_VALUE"
     else
      if  ( $NICE -$NICE_VALUE $TEST_NICE > /dev/null 2>&1 ) ;  then
        VERY_NICE="$NICE -$NICE_VALUE"
      fi
     fi
fi
if test "x$1" = "x"; then
  VERY_NICE=`echo $VERY_NICE | sed "s/$NICE_VALUE/NICE_VALUE/"`
fi
AC_MSG_RESULT($VERY_NICE)
AC_SUBST(VERY_NICE)
])