Square

Shell globbing lets you match filenames using patterns. While * matches any string and ? matches a single character, square brackets ([ ]) define character classes, enabling you to match one character from a specific set or range.

Matching a Range of Characters

Given a directory:

$ ls
fileA fileB fileC fileD fileE

You can match only fileA, fileB, and fileC by specifying a range inside brackets:

$ ls file[A-C]
fileA fileB fileC

Here, [A-C] matches any uppercase letter from A through C. Note that the dash (-) defines a range and must go from lower to higher:

$ ls file[C-A]
ls: cannot access 'file[C-A]': No such file or directory

Common Examples

Negated Character Classes

Prefix ! or ^ inside brackets to exclude characters or ranges:

$ ls
fileA fileB fileC fileD fileE

$ ls file[^A-C]
fileD fileE

$ ls file[!A-C]
fileD fileE

Listing Specific Characters

To match non-consecutive filenames such as fileA, fileC, and fileE, simply list them:

$ ls file[ACE]
fileA fileC fileE

Case Sensitivity

Globbing in Bash is case sensitive. If you have both uppercase and lowercase files:

$ touch filea fileb filec filed filee
$ ls
fileA fileB fileC fileD fileE filea fileb filec filed filee

To match only lowercase:

$ ls file[a-c]
filea fileb filec

To remove both lowercase and uppercase a–e, combine ranges:

$ rm file[a-eA-E]
$ ls
fileD fileE

Numeric Ranges and Negation

Numeric ranges behave the same way:

$ touch file1 file2 file3 file4 file5
$ ls file[1-3]
file1 file2 file3

$ ls file[4-5]
file4 file5

$ ls file[^1-3]
file4 file5

$ ls file[!1-3]
file4 file5

Multiple Character Classes

You can chain classes to match multiple positions. For example, to match filea1, filea2, fileb1, fileb2:

$ touch filea1 filea2 filea3 fileb1 fileb2 fileb3

$ ls file[a-b][1-2]
filea1 filea2 fileb1 fileb2

Each [a-b] matches one letter, and [1-2] matches one digit. If you try only [1-2], it won’t match because the letter is missing:

$ ls file[1-2]
ls: cannot access 'file[1-2]': No such file or directory

Literal Characters Inside Brackets

Inside character classes, special glob characters lose their meaning:

$ ls file[a][*]
ls: cannot access 'file[a][*]': No such file or directory

To use * as a wildcard, place it outside the brackets:

$ ls filea*
filea1 filea2 filea3

Or constrain both positions:

$ ls file[a][1-3]
filea1 filea2 filea3

Globbing vs. File Creation

Globs match existing filenames; they do not generate names. If you use a glob in a command like touch when no files match, the pattern is taken literally:

$ touch ?ail
$ ls
'?ail'

To produce a series of filenames based on a pattern, consider using brace expansion instead of globs.

Links and References

• Bash Pattern Matching
• KornShell Globbing
• Advanced Bash-Scripting Guide