Difference between revisions of "Regular expressions with Perl"

Revision as of 03:20, 16 June 2015

How to search and replace a word or phrase

• All matches

perl -pi -e 's/old string/new string/g' /path/to/the/file

This command line replaces all the instances of old string with new string that are found in `/path/to/the/file`. To replace only the first instance, remove the g at the end of the command.

• Conditional match

perl -pi -e 's/old string/new string/ if m/my unique string/' /path/to/the/file

This command line search only for the lines that matches my unique string and then replaces old string with new string

• Search and replace using bash shell variables

sed -i -e s%old string%$BASH_VARIABLE% /path/to/the/file

In order to get this done is convenient to use `sed` instead `perl` command.

Always use `-i -e` instead `-ie`, if not you will end up with another file with the same name but with an `e` at the end of the file name.

How to display an .rtf document on the CLi

cat my_document.rtf | sed  '/noformat/d; s/\\$//g; s/\\{/{/g; s/\\}/}/g'

How to remove/replace a whole line

• Conditional match

perl -pi -e '$_="" if m/my unique string/' /path/to/the/file

This command line removes all the lines that matches my unique string

How to work with "sed" command

Attached is a file Media:Sed1line.txt with a very useful list of sed commands called One-Liners for sed. Updated version is always available at http://sed.sourceforge.net/sed1line.txt