#!/bin/sh
#  this is a comment - any line that begins with # is a comment  (except the very first line of the file)
# the very first line of a  shell script file must be the "sha bang" line.
# this  "#!"  sequence is called a sha bang, followed by the full path of the particular shell we want to interpret/execute our commands
# every non-commented command will be interpreted/executed by the bourne shell program located in /bin/sh
echo "Hello Bourne shell!"
echo "executing  pwd command"
pwd
echo "executing ls command"
ls
echo "executing who command"
who
echo "executing cat shellscript.sh"
cat shellscript.sh
echo "executing grep -i shell *.sh"
grep -i shell  *.sh
echo "Goodbye Bourne shell. Now returning to my command shell which is" "$SHELL"