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Extract filename and extension in Bash

I want to get the filename (without extension) and the extension separately.

The best solution I found so far is:

NAME=`echo "$FILE" | cut -d'.' -f1`
EXTENSION=`echo "$FILE" | cut -d'.' -f2`

This is wrong because it doesn't work if the file name contains multiple . characters. If, let's say, I have a.b.js, it will consider a and b.js, instead of a.b and js.

It can be easily done in Python with

file, ext = os.path.splitext(path)

but I'd prefer not to fire up a Python interpreter just for this, if possible.

Any better ideas?

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45

You (perhaps unintentionally) bring up the excellent question of what to do if the "extension" part of the filename has 2 dots in it, as in .tar.gz... I've never considered that issue, and I suspect it's not solvable without knowing all the possible valid file extensions up front.

rmeador
– rmeador

2009-06-08 14:50:20 +00:00
Commented Jun 8, 2009 at 14:50
11

Why not solvable? In my example, it should be considered that the file contains two extensions, not an extension with two dots. You handle both extensions separately.

Juliano
– Juliano

2009-06-08 15:20:49 +00:00
Commented Jun 8, 2009 at 15:20
33

It is unsolvable on a lexical basis, you'll need to check the file type. Consider if you had a game called dinosaurs.in.tar and you gzipped it to dinosaurs.in.tar.gz :)

porges
– porges

2009-06-13 09:11:04 +00:00
Commented Jun 13, 2009 at 9:11
14

This gets more complicated if you are passing in full paths. One of mine had a '.' in a directory in the middle of the path, but none in the file name. Example "a/b.c/d/e/filename" would wind up ".c/d/e/filename"

Walt Sellers
– Walt Sellers

2012-03-05 18:49:56 +00:00
Commented Mar 5, 2012 at 18:49
20

clearly no x.tar.gz's extension is gz and the filename is x.tar that is it. There is no such thing as dual extensions. i'm pretty sure boost::filesystem handles it that way. (split path, change_extension...) and its behavior is based on python if I'm not mistaken.

v.oddou
– v.oddou

2013-11-26 07:29:17 +00:00
Commented Nov 26, 2013 at 7:29

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Extract filename and extension in Bash

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