Search and replace across many files in vim

16 Jan 2011

During some refactoring, I was hit with the need to do some serious bad-man search and replace across entire directories from within vim, because almost any alternative would be more painful than listening to Cher’s discography and watching The View simultaneously. After scouring Google results for a while, the only article I could find detailing this technique was a pretty good one by Ibrahim Ahmed.

I’ll summarize with an example. Let’s say you have a massive Python project, and you want to replace every call to certain accessor functions with a variable name. For example, wat.getZappaAlbum() becomes wat.zappaAlbum. Let’s say that your Python project is in the ~/Code/albums directory.

From within vim, we first have to specify which files we want to operate on.

:args ~/Code/albums/**/*.py

That is, we specify args as any Python file within any subdirectory of ~/Code/albums. You can use regular expressions here and, in fact, a few comments on Ibrahim’s site allude to piping in file names with a bash script.

After we have specified the files we want to act on, we specify the action. Let’s say we have two functions we want to replace: getTreasureFingersAlbum and getToroAlbum. We want to change them to treasureFingersAlbum and toroAlbum, respectively.

:argdo %s/get\(TreasureFingers\|Toro\)Album()/\l\1Album/gec | update

Now you’re whipping through each matching instance, yaying or naying each replacement like a glutton prince.

Wait, what? Let’s break down what’s going on here.

  • :argdo, unsurprisingly, specifies that we’re acting on the args we specified earlier.
  • %s/foo/bar/gc replaces each instance of foo with bar and prompts you before doing so.
  • get\(TreasureFingers\|Toro\)Album() matches either getTreasureFingersAlbum() or getToroAlbum() and the escaped parenthesis “capture” either TreasureFingers or Toro for later use in the replacement.
  • \l\1Album is the meat. The prefix, \l, tells vim to make the first character of the following back-reference lowercase. The next component, \1, is a back-reference to the capture (either TreasureFingers or Toro), and “Album” is simply appended to the replacement.
  • gec is used instead of gc because the inclusion of e avoids error messages in the case that we search a file and don’t find a match (this will happen).
  • | update simply saves the file after we’ve completed the first operation: the find and replace.

More information about case changes within regular expressions can be found here.