#! /bin/sh
#---------------------------------------------------------------------------#
# vim: ts=4 sw=4 et ft=sh
#---------------------------------------------------------------------------#
# @configure_input@
#---------------------------------------------------------------------------#
# Copyright (C) 1995-1997 The University of Melbourne.
# This file may only be copied under the terms of the GNU General
# Public License - see the file COPYING in the Mercury distribution.
#---------------------------------------------------------------------------#
#
# MERCURY_UPDATE_INTERFACE
#
# usage:
#   mercury_update_interface [-v] filename
#
# Move `filename.tmp' to `filename', but only if necessary.
# If they are identical, then we simply remove `filename.tmp',
# and leave `filename's time-stamp unaltered.
#
# If the `-v' (verbose) option is specified, then we print progress messages.
#
# Enviroment variables: none.

verbose=false

if test "$#" -ge 1 -a "$1" = "-v"
then
    verbose=true
    shift
fi

if test "$#" -ne 1
then
    echo "Usage: `basename $0` filename" 1>&2
    exit 1
fi

filename="$1"
    
if test ! -f "${filename}"
then
    ${verbose} && echo "creating \`${filename}'." 1>&2
    mv -f "${filename}.tmp" "${filename}"
    # Work-around for a parallel gmake problem
    exit 0
elif cmp -s "${filename}.tmp" "${filename}"
then
    ${verbose} && echo "\`${filename}' has not changed." 1>&2
    rm -f "${filename}.tmp"
else
    echo "\`${filename}' has CHANGED." 1>&2
    mv -f "${filename}.tmp" "${filename}"
    # Work-around for a parallel gmake problem.
    exit 0
fi