Rename the prefix of a bunch of files

prefmv

#!/usr/bin/env sh
# Usage:
# prefmv frompref topref files...
# 
# Changes the prefx from `frompref` to `topref`. Adds prefix `topref` if the file
# didn't have the prefix `frompref`
#
# Examples:
# prefmv main oldmain main.c main.java main.cpp
# prefmv main oldmain main*
# 
# It's best to use wildcards involving fromext for the file list, to be
# sure not to rename files lacking the extension, if you don't want that.

frompref=$1
shift
topref=$1
shift
files=$*

frompref=`echo $frompref | sed 's/\./\\\./'`

for i in $files; do
  j=`echo $i | sed s/\^${frompref}//`
  mv $i $topref$j
done