1.10 Special Characters

1.10 Special Characters

If you know people who are into Linux, and you have some inexplicable desire to discuss it with them, you should know a few names for some of the special characters that you'll encounter. If you are infinitely amused by this sort of thing, look at the Jargon File (http://catb.org/~esr/jargon/html/) or its printed companion, The New Hacker's Dictionary [Raymond].

Table 1-1 on the next page lists a select set of the special characters, what they are, what people call them, and their uses. You have already seen many of these characters in this chapter. Not all meanings of each character are identified because there are too many to list. Some utilities, such as the Perl programming language, use nearly every one of these special characters! Also, keep in mind that these are the American names for the characters.

Table 1-1: Special Characters

Character

Name(s)

Uses

*

star

Regular expression, wildcard character

.

dot

Current directory, file/hostname delimiter

!

bang

Negation, command history

|

pipe

Command pipes

/

(forward) slash

Directory delimiter, search command

\

backslash

Literals, macros (never directories)

$

dollar

Variable denotation, end of line

'

tick, (single) quote

Literal strings

`

backtick, backquote

Command substitution

"

double quote

Semi-literal strings

^

caret

Negation, beginning of line

~

tilde, squiggle

Negation, directory shortcut

#

hash, sharp, pound

Comments, preprocessor, substitutions

[]

(square) brackets

Ranges

{}

(curly) braces

Statement blocks, ranges

_

underscore

Cheap substitute for a space

Note?

You will often see control characters marked with a caret; for example, ^C for CONTROL-C.