After entering the bash shell by typing 'bash' at the command line,

paste the following at the command prompt:

cat > backup.sh <<-EOF

#!/bin/bash
usage()
{

echo ""
echo "usage: $0 <filename>"
echo ""
}

##Error checking##
if [ \$# -eq 0 ]
then
       usage
       exit 1
fi

dt=\`date '+%Y%m%d-%H:%M'\`
file=\$1
dash="-"
bkup=\$file\$dash\$dt
cp \$file \$bkup

EOF

chmod +x backup.sh

#-----end copy-----#


And also there is a way to avoid PATH dependency and simultaneously create a shortcut; 
add the following line to your ~/.tcshrc file (if you are using tcsh shell):

alias bk '/home/csgrad/aliseyed/backup.sh'

if you are using bash shell as default shell add the following line to your
~/.bashrc:
alias bk='/home/csgrad/aliseyed/backup.sh'

then just enter 'bk <filename>' at the command line for a quick backup.

If you do 'ls' with '-ltr' option included, the file listing is sorted by modification time 
in reverse order, so files with later a timestamp are shown toward the bottom of the listing, 
which is useful.

Although you probably should be using CVS or at least RCS, this is just a nice quick file backup method.