Creating numbered backup files

Now for a bonus here is a ready-to-run script that can be used to make numbered backup files. Before I came up with this (many years ago) I would go through the ritual of making the backup by hand. My numbering scheme was not always consistent, and I quickly realized it would be easier to have a script do it. This is something computers are really good at.

I call this script cbS. I wrote this so long ago I'm not even sure what it stands for. Maybe it was Computer Backup Script or something like that.

Chapter 3 – Script 13

#!/bin/sh
#
echo "cbS by Lewis 5/4/2017"

if [ $# -eq 0 ] ; then
 echo "Usage: cbS filename(s) "
 echo " Will make a numbered backup of the files(s) given."
 echo " Files must be in the current directory."
 exit 255
fi

rc=0                         # return code, default is no error
for fn in $*                 # for each filename given on the command line
do
 if [ ! -f $fn ] ; then      # if not found
  echo "File $fn not found."
  rc=1    ...