How to use character classes

Question

In one of my systems, when I run ls [:lower:]*, it will list all files that start with a lowercase letter.

In another one, it will give an error:

ls: cannot access [:lower:]*: No such file or directory

There are files that start with a lowercase in the working directory.

Running ls [[:lower:]]* instead, will work on both systems. I'd like to understand why ls [:lower:]* does not work in the second system and what is the proper way to use character classes.

Both are running Bash, but I would like an answer that I can apply to other shells as well.

score 3 · Accepted Answer · answered Mar 11 '19 at 11:10

3

Your first example didn't do what you thought it did; it instead listed all the filenames that started with any one of the following characters:

:
e
l
o
r
w

(those are the letters of lower, re-sorted). To use a character class, you must already be within the square brackets and then use [:lower:], as in your second example.

answered Mar 11 '19 at 11:10

Jeff Schaller

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Doh! Confess you laughed at me :) Thank you very much. – CharacterClass Mar 11 '19 at 11:13
1

Not at all, actually! It helps to have [seen this sort of thing before...](https://unix.stackexchange.com/q/347950/117549) – Jeff Schaller Mar 11 '19 at 11:24

How to use character classes

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