set Options

B.5 set Options

Table 2.6 lists the options that can be turned on with the set - arg command. All are initially off except where noted. Full Name s, where listed, are arguments to set that can be used with set -o . The Full Name s braceexpand , histexpand , history , keyword , and onecmd are not available in versions of bash prior to 2.0. Also, in those versions, hashing is switched with -d .

Table B.6. Options to set

Option

Full Name

Meaning

-a

allexport

Export all subsequently defined or modified variables .

-B

braceexpand

The shell performs brace expansion. This is on by default.

-b

notify

Report the status of terminating background jobs immediately.

-C

noclobber

Don't allow redirection to overwrite existing files.

-e

errexit

Exit the shell when a simple command exits with non-zero status. A simple command is a command not part of a while , until , or if ; or part of a && or list; or a command whose return value is inverted by ! .

 

emacs

Use emacs -style command-line editing.

-f

noglob

Disable pathname expansion.

-H

histexpand

Enable ! style history substitution. On by default in an interactive shell.

 

history

Enable command history. On by default in interactive shells .

-h

hashall

Disable the hashing of commands.

 

ignoreeof

Disallow CTRL-D to exit the shell.

-k

keyword

Place keyword arguments in the environment for a command.

-m

monitor

Enable job control (on by default in interactive shells).

-n

noexec

Read commands and check syntax but do not execute them. Ignored for interactive shells.

-P

physical

Do not follow symbolic links on commands that change the current directory. Use the physical directory.

-p

privileged

Script is running in suid mode.

 

posix

Change the default behavior to that of POSIX 1003.2 where it differs from the standard.

-t

onecmd

Exit after reading and executing one command.

-u

nounset

Treat undefined variables as errors, not as null.

-v

verbose

Print shell input lines before running them.

 

vi

Use vi -style command-line editing.

-x

xtrace

Print commands (after expansions) before running them.

-

 

Signals the end of options. All remaining arguments are assigned to the positional parameters. -x and -v are turned off. If there are no remaining arguments to set , the positional arguments remain unchanged.

--

 

With no arguments following, unset the positional parameters. Otherwise, the positional parameters are set to the following arguments (even if they begin with - ).

 



Learning the Bash Shell
Learning the bash Shell: Unix Shell Programming (In a Nutshell (OReilly))
ISBN: 0596009658
EAN: 2147483647
Year: 1998
Pages: 104

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