CODEWITHSUNDEEP
fileunixshfile-extension
Bappy
Bappy

Reputation: 641

How do I find out if a file name has any extension in Unix?

I need to find out if a file or directory name contains any extension in Unix for a Bourne shell scripting.

The logic will be:

  1. If there is a file extension
  2. Remove the extension
  3. And use the file name without the extension

This is my first question in SO so will be great to hear from someone.

Upvotes: 3

Views: 553

Answers (2)

tripleee
tripleee

Reputation: 189357

The concept of an extension isn't as strictly well-defined as in traditional / toy DOS 8+3 filenames. If you want to find file names containing a dot where the dot is not the first character, try this.

case $filename in
    [!.]*.*) filename=${filename%.*};;
esac

This will trim the extension (as per the above definition, starting from the last dot if there are several) from $filename if there is one, otherwise no nothing.

If you will not be processing files whose names might start with a dot, the case is superfluous, as the assignment will also not touch the value if there isn't a dot; but with this belt-and-suspenders example, you can easily pick the approach you prefer, in case you need to extend it, one way or another.

To also handle files where there is a dot, as long as it's not the first character (but it's okay if the first character is also a dot), try the pattern ?*.*.

The case expression in pattern ) commands ;; esac syntax may look weird or scary, but it's quite versatile, and well worth learning.

Upvotes: 4

qwertyboy
qwertyboy

Reputation: 1646

I would use a shell agnostic solution. Runing the name through:

cut -d . -f 1

will give you everything up to the first dot ('-d .' sets the delimeter and '-f 1' selects the first field). You can play with the params (try '--complement' to reverse selection) and get pretty much anything you want.

Upvotes: 0

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