| Character | Definition | |
*
 | 
Any sequence of zero or more characters. | |
?
 | 
A single character. | |
..
 | 
Parent directory. | |
[set]
 | 
A single character in the set set, for example `a' in [a-zA-z0-9]. | |
$var
 | 
The value of a shell variable var. |