Square brackets containing one or more characters stand for any one of the contained characters. For example:

[bch]at

matches bat, cat, or hat.

ls [abc]*

lists all files in the working directory the names of which start with a, b, or c, followed by any other sequence of zero or more characters. In other words, it lists all files whose names start with a, b, or c.

You can specify ranges of characters inside the square brackets by specifying the first character in the sequence, a hyphen (-), and the last character. For example:

[a–m]

This matches any character from a through m.

Suppose, for example, that you want to copy the contents of the working directory into two separate directories. You might enter:

cp [a–m]* dira

to copy all files with names beginning with the letters a through m to the directory dira, and then issue the second command:

cp [n–z]* dirb

to copy the rest of the files to the directory dirb. A command such as:

rm *.[a-z]

removes every file with a suffix consisting of a single lowercase letter.

If the first character inside a bracket construct is an exclamation mark !, the construct matches any character that is not inside the brackets. For example:

ls [!a–m]*

lists any file that does not begin with one of the letters in the range a through m.

In the same way:

rm [!0-9]*

removes any file with a name that does not start with a digit.