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Appendix B. Shell Special Characters and Variables

IN THIS APPENDIX

• Using special shell characters

• Using shell variables

Fedora provides bash as the default shell. Chapter 3 helps you become comfortable working in the shell. This appendix provides a reference of the numerous characters and variables that have special meaning to the bash shell. Many of those elements are referenced in Table B-1 (Shell Special Characters) and Table B-2 (Shell Variables).

Using Special Shell Characters

You can use special characters from the shell to match multiple files, save some keystrokes, or perform special operations. Table B-1 shows some shell special characters you may find useful.

Table B-1. Shell Special Characters

Character	Description
*	Match any string of characters.
?	Match any one character.
[ ... ]	Match any character enclosed in the braces.
' ... '	Remove special meaning of characters between quotes. Variables are not expanded.
" ... "	Same as simple quotes except for the escape characters ($ ` and \) that preserve their special meaning.
\	Escape character to remove the special meaning of the character that follows.
∼	Refers to the $HOME directory.
∼+	Value of the shell variable PWD (working directory).
∼-	Refers to the previous working directory.
.	Refers to the current working directory.
...	Refers to the directory above the current directory. Can be used repeatedly to reference several directories up.
$param	Used to expand a shell variable parameter.
cmd1 `cmd2` or cmd1 $(cmd2)	cmd2 is executed first. Then the call ...