Linux Awk Basic Structure and Workflow

1)Simple Linux awk utility Example.
$ ls | awk ' BEGIN { print "start"} { print } END { print  "stop"}'
start
ls.des
ls.sou
name
ouput.sh
ouput.sh.bak
ouput.sh.bak1
out.shbak
Request Forms
Request Forms.zip
test - output
test - output1
stop