Comment all lines start with a specific pattern

zeusys · 02-15-2016, 03:47 AM

Hi.
Assume you have a file like this :

Code:

#!/bin/bash
echo "<HTML>"
echo "<HEAD>"
echo "  <TITLE>"
echo "  The title of your page"
echo "  </TITLE>"
echo "</HEAD>"
echo ""
echo "<BODY>"
echo "  Contents"
echo "</BODY>"
echo "</HTML>"

Then you want to comment all of the lines which start with a specific pattern, in this example how to comment all lines start with echo command? In Vi,using sed,awk or how to ?

Please guide me
Thanks

pan64 · 02-15-2016, 03:55 AM

have you tried sed or awk already? Where did you stuck?

zeusys · 02-15-2016, 04:46 AM

I don't know who should I do that? either using awk or sed?

TobiSGD · 02-15-2016, 05:00 AM

In Vim:

Code:

:%s/^echo/#echo/g

The string you would use for sed should look pretty similar.

allend · 02-15-2016, 05:53 AM

Using sed, you specify that you only wish to change lines starting with echo by using the regular expression "^echo", where the circumflex character matches the start of a line.
This will output to your screen.

Code:

sed 's/^echo/#echo/' <your file>

To redirect the output to a new file.

Code:

sed 's/^echo/#echo/' <your file> > <new file>

Adding the -i option will change the original file.

Code:

sed -i 's/^echo/#echo/' <your file>

An alternative is to use a backreference, which is trivial here, but often powerful.

Code:

sed 's/^\(echo\)/#\1/' <your file>