#!/bin/sh
#
# changein
#
# AUTHOR:
#   Dan Harkless                                                    <opensource@
#   http://harkless.org/dan/software/                              harkless.org>
# 
# COPYRIGHT:
#   This file is Copyright (C) 2001 by Dan Harkless, and is released under the
#   GNU General Public License <http://www.gnu.org/copyleft/gpl.html>.
#
# USAGE:  
#   % changein <file1> [<file2>...] '<old pattern>' '<new pattern>'
#
# DESCRIPTION:
#   Calls sed on multiple files to change one pattern to another in-place.
#   "perl -e 's/<old pattern>/<new pattern>/g' -i -p <file1> [<file2>...]" is a
#   better solution to this problem, but I didn't become aware of that
#   particular option combination until six years after starting this script.
#   Luckily I never got around to expending the energy to rewrite this shell
#   script as a more fault-tolerant (but grossly overwritten, I now realize)
#   Perl script.
#
#   Oh well.  I guess this script could still come in handy for someone on a
#   system without perl.  It also reports whether <old pattern> is found or not
#   in each file processed, which can be handy sometimes.
#
# DATE        MODIFICATION
# ==========  ==================================================================
# 2001-10-23  Retired in favor of "perl -e 's/<old>/<new>/g' -i -p <files>".
# 2001-04-04  While avoiding single-quoting on $old_pattern and $new_pattern on
#             "Changing..." message, need to double-quote to avoid globbing.
# 2000-03-21  Oops.  sed uses regexps by default -- we need to use egrep to see
#             if the file contains the pattern, not fgrep.
# 1998-10-22  fgrep doesn't have a -q option everywhere: redirect to /dev/null.
# 1998-07-13  Check if files are writable before trying to overwrite them.  If
#             they're not, we'll just error and leave them to be done manually.
# 1998-07-13  Only run sed on files that fgrep says contain <old pattern>, so we
#             don't change timestamps on files unnecessarily.
# 1998-07-07  Doing `sed $expr $orig > $temp; mv $temp $orig` breaks hard links
#             and screws up permissions.  To prevent this, instead do:
#             `cp $orig $temp; sed $expr $temp > $orig; rm $temp`.
# 1997-08-21  Re-wrote as a sh script.  Actually, I now realize this would be 
#             easier and more fault-tolerant in Perl.
# 1995-12-28  Original csh script.

progname=`basename $0`

# Make sure at least 3 parameters were passed.
if [ $# -lt 3 ]; then
  echo "usage: $progname <file1> [<file2>...] '<old pattern>' '<new pattern>'"
  exit 1
fi

# Shift off the files so that $1 and $2 are the old and new patterns.
while [ $# -gt 2 ]; do
  files="$files $1"
  shift
done
old_pattern="$1"
new_pattern="$2"

# Check to see if the old or new patterns contain the character(s) we want to
# use as the sed separator character.
if [ `echo "$old_pattern $new_pattern" | fgrep -c @` = 0 ]; then
  sed_expr="s@$old_pattern@$new_pattern@g"
elif [ `echo "$old_pattern $new_pattern" | fgrep -c \^` = 0 ]; then
  sed_expr="s^$old_pattern^$new_pattern^g"
else
  echo "$progname: D'oh!!!  Your pattern contains both a '@' and a '^'. "
  echo "          changein needs an additional version of the sed call."
  exit 1
fi

# egrep for the pattern in each file and run sed on those that contain it.
for f in $files; do
  if egrep "$old_pattern" $f > /dev/null; then
    if [ -w $f ]; then
      echo $f": Changing '""$old_pattern""' to '""$new_pattern""'..."
      tempfile=$f-changein-$HOST-$$
      trap "mv -f $tempfile $f" 1 2 3 15
      cp -f -p $f $tempfile
      sed "$sed_expr" $tempfile > $f
      sed_status=$?
      if [ $sed_status = 0 ]; then
	rm -f $tempfile
      else
	mv -f $tempfile $f
	echo "$progname: Aborting."
	exit $sed_status
      fi
    else
      echo $f": **************** Not writable!!!  Skipping!!! ****************"
    fi
  else
    echo $f": '"$old_pattern"' not found."
  fi
done