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LiveFire Labs' UNIX and Linux Operating System Fundamentals
course was very enjoyable. Although I regularly used UNIX systems
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Senior Technical Writer
Nuance Communications, Inc.
Montréal, Canada
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UNIX Special Characters (Metacharacters) - Asterisk, Question
Mark, Brackets, and Hyphen
Special Characters (Metacharacters)
Special characters, or metacharacters, have a special meaning to the
shell. They can be used as wildcards to specify the name of a file
without having to type out the file's full name. Some of the most
commonly used metacharacters are "*", "?", "[]", and "-".
The Asterisk
The * (asterisk) metacharacter is used to match any and all
characters. Typing the following command will list all files in the
working directory that begin with the letter l regardless of what
characters come after it:
$ ls l*
The * (asterisk) metacharacter can be used anywhere in the filename.
It does not necessarily have to be the last character.
The Question Mark
The ? (question mark) metacharacter is used to match a single
character in a filename. Typing the following will list all of the
files that start with "livefirelabs" and end with a single character:
$ ls livefirelabs?
Like the asterisk, the ? (question mark) metacharacter can be used as
a substitution for any character in the filename.
Brackets
Brackets ([…]) are used to match a set of specified characters. A
comma separates each character within the set. Typing the following
will list all files beginning with "a", "b", or "c":
$ ls [a,b,c]*
The Hyphen
Using the - (hyphen) metacharacter within [] (brackets) is used to
match a specified range of characters. Typing the following will list
all files beginning with a lowercase letter of the alphabet:
$ ls [a-z]*
If there are directory names meeting the specified range, their name
and contents will also be displayed.
TIP: Although possible, it is highly recommended that
you do not create file names containing metacharacters.
