Listing files with grep?

I have a directory that contains the following files:

file1a file1ab file12A2 file1Ab file1ab

I want to list all files that start with file1 and followed by two letter at most!

The solution I have proposed is as follows:

ls | grep -i file1 [az] {2}

But it does not work!

I want to know why? and how to list?

0

3 Answers

You don't need piping, grep or ls. Just use shell globbing.

In bash, using extglob pattern (should be enabled by default in interactive sessions, if not do shopt -s extglob to set it first):

file1@(|?|??)

? matched any single character, @(||) selects any of the patterns separated by |.

If you only meant to match any characters between a-z and A-Z, use use character class [:alpha:] which denotes all alphabetic characters in the current locale:

file1@(|[[:alpha:]]|[[:alpha:]][[:alpha:]])

Example:

$ ls -1
file1
file112
file11a
file12A2
file1a
file1ab
file1Ab
file1as
file2
fileadb
$ ls -1 file1@(|[[:alpha:]]|[[:alpha:]][[:alpha:]]))
file1
file1a
file1ab
file1Ab
file1as

---

zsh supports this natively:

file1(|[[:alpha:]]|[[:alpha:]][[:alpha:]])

---

I am answering this portion very reluctantly, upon request from OP.

Any future reader, Don't parse ls, use globbing.

Using ls and grep:

ls | grep -E '^file1[[:alpha:]]{,2}$'

Example:

% ls | grep -E '^file1[[:alpha:]]{,2}$'
file1
file1a
file1ab
file1Ab
file1as

13

Whats about find?

find . -maxdepth 1 -regextype posix-egrep -iregex '\./file1[a-z]{,2}.*'

2

find with -regex flag is more appropriate for this sort of job, especially since it's a general rule that output of ls should never be parsed.

However, you've stated that you are looking for files only in one directory ( not descending into subdirectories ), and that you'd specifically want ls and grep. The solution is

\ls | grep -E 'file1[a-z]{2,}' 

Considering also that you are searching in the current directory, but avoiding parsing ls, here's another solution

 for file in * ; do echo "$file" | grep -E 'file1[a-z]{2,}' ;done
./file1ab
./file1abc

In my current directory, I have two files, file1ab and file1abc. In both cases, the result is the following:

xieerqi:$ for file in * ; do echo "$file" | grep -E 'file1[a-z]{2,}' ;done
./file1ab
./file1abc
xieerqi:$ \ls | grep -E 'file1[a-z]{2,}'
file1ab
file1abc

Your Answer

Sign up or log in

Sign up using Google Sign up using Facebook Sign up using Email and Password Submit

Post as a guest

Post Your Answer Discard

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy