How can I get files with numeric names using ls command?

Question

In linux commandline, how can I list down only numeric(only names with 0 to 9) file names in the current directory?

This is a follow-on question to How can I get the list of process ids on the system in linux command prompt?, where I've run ls on /proc/. I'm now trying to exclude everything except the process ID directories.

Solution 1

Using ls piped to grep -E (extended grep with additional regexp capabilities) to search for all filenames with only numeric characters:

ls | grep -E '^[0-9]+$'

Solution 2

If you're wanting to use ls, you could use:

ls *[[:digit:]]*

The * splat operator will match any [[:digit:]]. You could also use:

ls *[0-9]*

Which also matches file or directory with a digit 0-9.

If you have subdirectories that match the glob pattern, you can use the -d switch to make ls not recurse into them.

Solution 3

Despite of your question title, I want to present you a solution with find. It has a regex option (-regex), so [0-9]* will match file names consisting solely out of digits.

To find only files (-type f) recursively below the current directory (.) use

find . -type f -regex ".*/[0-9]*"

The .*/ in the regex is necessary, because regex "is a match on the whole path, not a search." (man find). So if you want to find only files in the current dir, use \./ instead:

find . -type f -regex "\./[0-9]*"

However, this is not very optimal, as find searches recursively also in this case and only filters out the desired results afterwards.

Comments

[ckujau]

Note: this will list files starting with a digit. Add another "*" at the end to match also files with digits inbetween.

[suspectus]

These patterns will only match files which end with a numeric character.

[techfun]

Hello, Thanks for reply. I have some confusion with ls *[0-9] I am getting list of files inside sub directories and files with numeric. And for sub directories it is again listing all directories.

[suspectus]

why downvote please?

[user]

@techfun Add the -d switch.

[user]

Not my downvote, but I strongly suspect (no pun intended) that it's because you shouldn't parse the output of ls. Even more so in a case like this, where perfectly valid alternatives exist (see for example mpy's answer).

[suspectus]

hmm... despite ls specifically requested by OP. Thanks for link.

[user]

You're right, the question title says ls, but the question itself is much broader and only asks how to list files with numeric file names from the command line. ls is one way to do that (and it's one way to list files), but far from the only one. Try e.g. echo * some time.

[Victoria Stuart]

I think this is a really excellent answer; thank you for the recursive / mon-recursive versions!

[phuclv]

Why not parse ls?

[phuclv]

so what makes it different from tijko's answer?

[MOHRE]

tijko's answer does not work correctly. It would match a2g.test but my answer just match numbers.

[MOHRE]

As @techfun mentioned "only numeric(only names with 0 to 9) file names" tijko's answer doesn't fit.