Shell Programming and Scripting

#!/bin/ksh
ec=0
IAm=${0##*/}
if [ $# -ne 2 ]
then    printf "Usage:\t%s list_file dest_dir\n" "$IAm" >&2
        printf "\t\$HOME/dest_dir must be an existing directory\n" >&2
        exit 1
fi
if [ ! -f "$1" ]
then    printf "%s: \"%s\" is not a regular file\n" "$IAm" "$1" >&2
        exit 2
fi
if [ ! -d ~/"$2" ]
then    printf "%s: \"%s\" is not a directory\n" "$IAm" ~/"$2" >&2
        exit 3
fi
while read -r file
do      if ! cp "$file" ~/"$2/$file.bak"
        then    ec=4
        fi
done < "$1"
exit $ec