Find string in text file (bash script)

[candyme]

Hello!

Please, help me to write such script (bash script).
I have some text file with name filename.txt
I must check if this file contains string "test-string-first", I must cut from this file string which follows string "keyword-string:" and till first white-space and save it to some variable.

For example. File:

 PHP Code:
Start 15022011 Eng 12-3-42
SN1232324422 11 test-string-first
SN322211 securities
HH keyword-string:123456321-net mark (11-22) 
  

This file contains "test-string-first" and I need to get 123456321-net string (between "keyword-string:" and first space)

and i want to have such code structure:

 if (check_exists_of('test-string-first','filename.txt') then
 MYVAR = awk .... filename.txt
 echo $MYVAR
else
 echo 'file doesn't contain '''test-string-first'' string!'
 fi 
  

help me pls to change check_exists_of('test-string-first','filename.txt') and MYVAR = awk .... filename.txt statements to the correct.

[Lakshmipathi]

I would provide some hints . I hope you can take it from there.

grep command is used to search for text.
like
ret=`grep "searchtext" Filename.txt`

If grep command pass (ie it found "searchtext" ) $? will be equal to zero.