#! /bin/sh
#
#         File:	vpurge.sh
#     Abstract:	Remove old file versions created by emacs.
#        Usage: See -h for help.
#       Author: Bill.Costa@unh.edu
#
#==============================================================================

help () { cat <<EOF

  usage: $0 [-h|-t|-i|-v|-f] [file...]

  Given one or more filenames, such as:

         myfile

  we purge all emacs style backup version files using the naming
  convention of

         myfile~
  and
         myfile.~nnnn~

  where 'nnnn' is the version number of the file starting at 1.  
  If no file is specified, then all versions are purged in the 
  current default directory, but only if the original file also 
  exists in that same directory.

  It is an error to explicitly specify a version file, i.e. enter
  or to cause entry of a file ending with '~'.   Only the source
  the backup files were derived from should be specified.  For 
  example:

         $0 myfile*

  would cause matches on any backup versions of 'myfile' such as
  'myfile~' and 'myfile.~3~' to be expanded onto the command line.
  No purge of any file is done if such a file specification error
  is detected anywhere on the command line.

  Options:

    -h   display Help (this message) and exit without processing
    -t   Test mode; show files matched but don't delete them
    -i   Interactive mode; ask before removing each file
    -v   Verbose mode; log to STDERR as each file is about to be deleted
    -f   Force removal; recommended for scripts (see man page for rm)

  Default is to quietly purge all matched version files.  If more than
  one option is specified, the last one takes precedence.  (This is
  handy for alias definitions.)

  Bugs and limitations: Doesn't allow the specification of a just a 
  directory in order to purge the contents of that directory.  Probably
  should just ignore *~ files rather than complaining in order to make
  wildcarding easier.  We do not automatically seek out and purge
  backup versions of 'dot' files.
EOF
}

#------------------------------------------------------------------------------

die ()  # $1 = integer exit code; $2 = message to STDERR; $n = additional lns

#  Send an error message to STDERR and abort script with provided exit code.

{
    /bin/echo "! `basename $0` ($1): $2" >&2
    shift 2
    while [ $# -gt 0 ]
    do
        echo "_ $1" >&2
        shift
    done
    if [ $1 -gt 0 ]
    then exit $1
    else echo "_ internal logic error, forcing error exit"
         exit 9
    fi;
}

#==============================================================================
#  MAIN LINE  =================================================================
#==============================================================================

    verbose=off
    interactive=off
    test=off
    force=off


#-------------------------------+
# Process command line options	|
# first.			|
#-------------------------------+

    while [ $# -gt 0 ]
    do
        case "$1" in
            -h)  help;
                 exit 0;;
            -i)  verbose=off; interactive=on;  test=off; force=off;;
            -v)  verbose=on;  interactive=off; test=off; force=off;;
            -t)  verbose=off; interactive=off; test=on;  force=off;;
            -f)  verbose=off; interactive=off; test=off; force=on;;
    	    --)  shift; break;;
    	    -*)  echo >&2 "invalid option '$1'; try -h for help"
    		 exit 1;;
             *)  break;;
        esac
        shift
    done


#-------------------------------+
# "$@" now contains all file	|
#  names.  If there are none,	|
#  then generate our own.  If	|
#  there are still none, exit.	|
#-------------------------------+

    if [ $# -gt 0 ]
    then allFiles="$@"
    else allFiles="`(ls -1 | grep -v '~$') 2>/dev/null`"
    fi;
    [ "$allFiles" = "" ] && exit;


#-------------------------------+
# Prescan our args for any	|
# problems.			|
#-------------------------------+

    for nxtFile in $allFiles
    do
        case "$nxtFile" in
          *~) die 1 "invalid file specified: $nxtFile" "try -h for help";;
        esac
    done


#-------------------------------+
# Now do the deed.		|
#-------------------------------+

    for next in $allFiles
    do
        hit="`ls $next~ 2>/dev/null`"
        hit="$hit `(ls $next.~*~ 2>/dev/null | egrep '\.~[0-9]+~$')`"

        if [ "$hit" = " " ]
        then :
        elif [ "$test" = "on" ]
        then ls $hit
        elif [ "$interactive" = "on" ]
        then rm -i $hit
        elif [ "$verbose" = "on" ]
        then rm -e $hit
        elif [ "$force" = "on" ]
        then rm -f $hit
        else rm $hit
        fi
    done

#==[ EOF: vpurge.sh ]==========================================================