Linux Secrets: How to Use Wildcards with ls

Create Custom Search Patterns for ls Using Wildcard Characters

Dec 4, 2008
Mark Alexander Bain

Linux Search Patterns on Linux - Mark Alexander Bain

Wildcard characters can be used with ls on Linux to provide a listing of the contents of a directory, but only selecting a very precise set of files.

The contents of any Linux directory can be listed by using the ls command and it's very good at its job; however this useful tool can be improved by:

customizing the ls output by using its many options (see Linux Secrets: How to Customize the ls Output)
refine the file selection criteria by using Linux wildcards such as:
- the asterisk (*)
- the question mark (?)
- brackets ([])

Using ls Without Wildcards

The most common way to use ls is to view all of the files in a Linux directory - in this case the -1 option is used to view the files vertically:

$ ls -1

process_article

Using ls with Wildcards.html

writing_status

writing_status~

In this case all of the files in the directory have been displayed; however this list can be filtered by introducing a search pattern.

Using an Asterisk in the ls Search Pattern

The asterisk (*) is used to represent a search pattern that contains anything; therefore to find any file with a name starting in proc, for example, the following would be entered onto the command line:

$ ls -1 proc*

process_article

An asterisk can appear in multiple places in search string, and so the following would search for any files with stat anywhere in the name:

$ ls -1 *stat*

writing_status

writing_status~

Or a file name starting with w, an underscore in it somewhere and ending in a tilde (~):

$ ls -1 w*_*~

writing_status~

Finally the search pattern may be one looking for a particular file type, for instance an html file:

$ ls -1 *.html

Using ls with Wildcards.html

Using a Question Mark in the ls Search Pattern

The asterisk represents a search pattern containing any number of characters, however a question mark represents a search pattern containing one, and only one, character:

$ ls -1 writing_status?

writing_status~

Using Brackets in the ls Search Pattern

Brackets, like question marks, are used to represent a single character; but the difference is that the brackets allow a choice of characters. The following will search for any file whose name contains either a upper or lower case W:

$ ls -1 *[Ww]*

Using ls with Wildcards.html

writing_status

writing_status~

It is also possible to search for names starting with a defined pattern, for instance any upper case letter:

$ ls -1 [A-Z]*

Using ls with Wildcards.html

Although, it's worth noting that this particular pattern will only work with certain shells, for example it will work with Korn but not Bash.

Combining Asterisks, Brackets and Question Marks in the Same ls Search Pattern

Obviously it is possible to combine all of the wildcard characters in a search string that provide a very precise pattern - in this example a pattern to match the files with a suffix starting with upper or lower case H followed by any three characters:

$ ls -1 *.[Hh]???

Using ls with Wildcards.html

Literal characters in the ls Search Pattern

Many characters (such as dollar signs and spaces) do not work within search strings because each has its own meaning; however, the trick is to turn the special character into a literal character by adding a backslash in front it; so the following would find any file with a space in its name:

$ ls -1 *\ *

Using ls with Wildcards.html

Summary

A search pattern using wildcard characters can be added to the ls command; these wildcards are::

* - searches for any pattern
? - searches for one, and only one, character
[] - seaches for a single character, but allows a choice of characters

And, of course, all of the wildcards can be combined to provide a very precise search pattern.

Mark Alexander Bain - Mark Alexander Bain is a writer, Mo Bro and consultant for all aspects of software development at dsquared. He has also written regularly ...