:
# newext: change filename extension
# @(#) newext.sh 1.1 93/04/13
# 90/06/06 john h. dubois iii (john@armory.com)
# 90/11/14 changed ksh-specific code to hybrid: if running under Bourne,
#          uses expr instead of ksh builtin ops.  Removed SYSV specific code.
# 91/08/06 added -t option
# 92/11/06 made earlier code actually work!
# 93/04/13 If no filenames given, act on files in current dir

name=newext
usage="Usage: $name [-th] <oldext> <newext> [filename ...]"

case "$1" in
-t) 
    test=true
    shift
    ;;
-h) 
    echo \
"$name: Rename all given files that end in oldext with newext replacing oldext.
$usage
If no filenames are given, all files in the current directory that end
in oldext are acted on (no filename is equivalent to '*').
Options:
-h: Print this help.
-t: Test: No action is taken except to print the mv commands that would
    be executed if -t was not given."
    exit 0 
    ;;
esac

oldext=$1
newext=$2

case $# in 
[01])
    echo "$usage\nUse -h for help."
    exit 1
    ;;
2)
    shift ; shift
    set -- *
    ;;
*)
    shift ; shift
    ;;
esac

found=

for file
do
    case "$file" in
    *$oldext) 
	# if $PS3 set, use ksh builtins
	if [ -n "$PS3" ]; then
	    newname="${file%$oldext}$newext"
	else
	    newname=`expr "$file" : "\(.*\)$oldext`"$newext"
	fi
	if [ -n "$test" ]; then
	    echo mv "$file" "$newname"
	else
	    mv "$file" "$newname"
	fi
	found=true;;
    esac
done

if [ -z "$found" ]; then
    echo "No files ending in \"$oldext\"."
fi