Shell Programming and Scripting

Thank you Bakunin.
Vgersh, your second option was helpful; it does the job in a single command though it is not difficult or consumes time to redirect and then rename. Thank you all :-)

---------- Post updated at 08:01 AM ---------- Previous update was at 08:00 AM ----------

Vgersh,
Sorry to say, but the the first option is still not helpful.

Code:

printf '/hotbackup/s!^!#!g\n1,$~\nwq!\n' | ex -s myFile

Code:

printf '/hotbackup/s!^!#!g\n1,$~\nwq!\n' | ex -s myFile

This is appending # on every line

Code:

printf '/hotbackup/s!^!#!g\nwq!\n' | ex -s myFile

This is working but not appending globally. It is only working on the line where it first finds the keyword and does not consider the rest of the file.
Sorry for I did not see it before as the file was huge and I cross checked the end page of it

The problem with vgersh99's ex scripts is that they seem to assume an implicit i/o loop, much like sed, which reads in each line and then executes the script for each one. That's not the case. '/hotbackup/s/regexp/repltext/g\nwq\n' will search for the next instance of a line with 'hotbackup', make substitutions on that line only, then write and quit. To mark multiple lines for processing, the global command is needed. Perhaps the following is what is sought:

Code:

printf '%s\n' g/hotbackup/s/^/#/ wq | ex -s myFile

or with ed:

Code:

printf '%s\n' g/hotbackup/s/^/#/ w q | ed -s myFile

Regards,
Alister

Thank you Alister, second command works. Again, the first command append # on every line ;-)