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 ...

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