Linux in a Nutshell, Fifth Edition

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Chapter 6: The Bash Shell and Korn Shell

This is the Title of the Book, eMatter Edition

Copyright © 2006 O’Reilly & Associates, Inc. All rights reserved.

.

. file [arguments]

Read and execute lines in file. file does not have to be executable,

but must reside in a directory searched by PATH. The arguments

are stored in the positional parameters. If Bash is not in POSIX

mode and file is not found in PATH, it will look in the current

directory for file.

[[ ]]

[[ expression ]]

Same as test expression or [ expression ], except that [[ ]] allows

additional operators. Word splitting and filename expansion are

disabled. Note that the brackets ([]) are typed literally and that

they must be surrounded by whitespace.

Additional Operators

&& Logical AND of test expressions (short circuit).

|| Logical OR of test expressions (short circuit).

< First string is lexically “less than” the second.

> First string is lexically “greater than” the second.

alias

alias [options] [name[='cmd']]

Assign a shorthand name as a synonym for cmd.If='cmd' is

omitted, print the alias for name;ifname is also omitted, print all

aliases. If the alias value contains a trailing space, the next word on

the command line also becomes a candidate for alias expansion.

See also unalias.

These aliases are built into ksh88. Some use names of existing

Bourne shell or C shell commands:

autoload='typeset -fu'

false='let 0'

functions='typeset -f'

hash='alias ...