Questions about using Regex Search & Replace in gedit

Question

I am trying to use the Regex Search & Replace plugin of gedit.

1. I want to search for a digit that repeats 2 or 3 times, so I thought the regex was

   [0-9]\{2,3\}
   

   But it doesn't match the targets it should, such as "22".

2. I want to find a word "Notes" exactly, so I thought it would be

   \<Notes\> 
   

   But it doesn't work either.

3. How to add a "#" in front of a string of any three digits "[0-9][0-9][0-9]"? e.g. "123" becomes "#123".

I was wondering if I made some mistake? I am using Basic Regex. What type of Regex is used in the plugin? How can I learn how to use this plugin?

Solution 1

You should not need to escape your regex characters. Your first example should be:

[0-9]{2,3}

Your second example should be:

\bNote\b

For the third situation, you'll need to match things before and after, then use back-references:

(.*)([0-9]{3}.*)

with the replacement being:

\1p\2

For more details, see pydoc re that will tell you about Python regular expression syntax, or the online documentation.

Solution 2

As Kees says, the plugin uses Python's re module syntax, which also has a How-To on the python site.

I also recommend installing and playing around with kodos .
It's a python regular expression tester (it calls itself a 'debugger'), and includes a quick reference regex sheet as well as a shorter version of the re module documentation.

The regular-expression.info site has a nice comparison of different implementations of regular expression meta-languages. There's a decent section on the python flavor there as well.

Comments

[Tim]

@igbelacqua: Thanks! I guess Kodos is for KDE. If I am correct, it can be installed on Gnome but not the best if there is some other native software for Gnome. Do you know what the natives are?

[belacqua]

Hmm -- Kodos does have Qt dependencies, but it's not a KDE app per se that I can see. I run basic Ubuntu (Gnome), and it hasn't been out of place . Another option is kiki -- it's a python-wxgtk2.6 application -- not as full-featured. I used it before finding kodos. Another tester option that doesn't require an install is pythonregex.com -- it says it was inspired by Kodos, and it's clean and useful. It's possibly the easiest to use of the three.