A metacharacter (sometimes spelled meta character or meta-character ) is a special character in a program or data field that provides information about other characters. A metacharacter can express an idea about how to process the characters that follow the metacharacter, as the backslash character sometimes is used to indicate that the characters following it are to be treated in a special way. A common metacharacter usage is the wildcard character , which can represent either any one character or any string of characters. In UNIX shell s, metacharacters include, but are not limited to these:
* ; | ] [ ?
Each of these characters has a special meaning on the command line, and their use must be avoided for purposes other than their special meaning.