> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Square
> This article explains square bracket globbing in Bash for matching filenames using character classes and ranges.
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:
```bash theme={null}
$ ls
fileA fileB fileC fileD fileE
```
You can match only `fileA`, `fileB`, and `fileC` by specifying a range inside brackets:
```bash theme={null}
$ 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:
```bash theme={null}
$ ls file[C-A]
ls: cannot access 'file[C-A]': No such file or directory
```
### Common Examples
| Pattern | Matches | Description |
| ---------- | ------------------- | ------------------------ |
| file\[A-C] | fileA, fileB, fileC | Uppercase A–C |
| file\[a-c] | filea, fileb, filec | Lowercase a–c |
| file\[1-3] | file1, file2, file3 | Numeric 1–3 |
| file\[ACE] | fileA, fileC, fileE | Specific letters A, C, E |
## Negated Character Classes
Prefix `!` or `^` inside brackets to exclude characters or ranges:
```bash theme={null}
$ ls
fileA fileB fileC fileD fileE
$ ls file[^A-C]
fileD fileE
$ ls file[!A-C]
fileD fileE
```
In Bash both `!` and `^` work for negation. POSIX shells require `!` at the start of the class.
## Listing Specific Characters
To match non-consecutive filenames such as `fileA`, `fileC`, and `fileE`, simply list them:
```bash theme={null}
$ ls file[ACE]
fileA fileC fileE
```
## Case Sensitivity
Globbing in Bash is case sensitive. If you have both uppercase and lowercase files:
```bash theme={null}
$ touch filea fileb filec filed filee
$ ls
fileA fileB fileC fileD fileE filea fileb filec filed filee
```
To match only lowercase:
```bash theme={null}
$ ls file[a-c]
filea fileb filec
```
To remove both lowercase and uppercase `a–e`, combine ranges:
```bash theme={null}
$ rm file[a-eA-E]
$ ls
fileD fileE
```
When mixing ranges, list them in the order you want matched: here `a-e` before `A-E`.
## Numeric Ranges and Negation
Numeric ranges behave the same way:
```bash theme={null}
$ 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`:
```bash theme={null}
$ 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:
```bash theme={null}
$ 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:
```bash theme={null}
$ ls file[a][*]
ls: cannot access 'file[a][*]': No such file or directory
```
To use `*` as a wildcard, place it outside the brackets:
```bash theme={null}
$ ls filea*
filea1 filea2 filea3
```
Or constrain both positions:
```bash theme={null}
$ 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:
```bash theme={null}
$ touch ?ail
$ ls
'?ail'
```
To produce a series of filenames based on a pattern, consider using **brace expansion** instead of globs.
Globbing won’t create files—only match them. If you expect new files, use brace expansion or a loop.
## Links and References
* [Bash Pattern Matching](https://www.gnu.org/software/bash/manual/html_node/Pattern-Matching.html)
* [KornShell Globbing](https://www2.gnu.org/software/ksh/manual/html_node/Globbing.html)
* [Advanced Bash-Scripting Guide](https://tldp.org/LDP/abs/html/globbingref.html)