bash Cookbook

Finding Files Irrespective of Case

Problem

Some of your MP3 files end with .MP3 rather than .mp3. How do you find those?

Solution

Use the -iname predicate (if your version of find supports it) to run a case-insensitive search, rather than just -name. For example:

$ find . -follow -iname '*.mp3' -print0 | xargs -i -0 mv '{}' ~/songs

Discussion

Sometimes you care about the case of the filename and sometimes you don’t. Use the -iname option when you don’t care, in situations like this, where .mp3 or .MP3 both indicate that the file is probably an MP3 file. (We say probably because on Unix-like systems you can name a file anything that you want. It isn’t forced to have a particular extension.)

One of the most common places where you’ll see the upper- and lowercase issue is when dealing with Microsoft Windows-compatible filesystems, especially older or “lowest common denominator” filesystems. A digital camera that we use stores its files with filenames like PICT001.JPG, incrementing the number with each picture. If you were to try:

$ find . -name '*.jpg' -print

you wouldn’t find many pictures. In this case you could also try:

$ find . -name '*.[Jj][Pp][Gg]' -print

since that regular expression will match either letter in brackets, but that isn’t as easy to type, especially if the pattern that you want to match is much longer. In practice, -iname is an easier choice. The catch is that not every version of find supports the -iname predicate. If your system doesn’t support it, you could try tricky ...