#!/bin/bash

PATH=/bin:/usr/bin
script=$(basename $0)
case $# in

    0)
       vim
       exit 0
       ;;

    1)
       if [ ! -f "$1" ]
            then
                vim "$1"
                exit 0
            fi
       if [ ! -r "$1" -o ! -w "$1" ]
            then
                echo "$script: check permissions on $1" 1>&2
                exit 1
            else
                editfile=$1
            fi
       if [ ! -w "." ]
            then
                echo "$script: backup cannot be " \
                    "created in the working directory" 1>&2
                exit 1
            fi
       ;;

    *)
       echo "Usage: $script [file-to-edit]" 1>&2
       exit 1
       ;;
esac

tempfile=/tmp/$$.$script
cp $editfile $tempfile
if vim $editfile
    then
        mv $tempfile bak.$(basename $editfile)
        echo "$script: backup file created"
    else
        mv $tempfile editerr
        echo "$script: edit error--copy of " \
            "original file is in editerr" 1>&2
fi