B.1. Invocation

Table B-1 and Table B-2 list the options you can use when invoking current versions of bash and the older 1.x version, respectively.^[1] The multicharacter options must appear on the command line before the single-character options. In addition to these, any set option can be used on the command line; see Table B-7. Login shells are usually invoked with the options -i (interactive), -s (read from standard input), and -m (enable job control).

^[1] At the time of writing, the old 1.x versions of bash are still used. We strongly recommend that you upgrade to the latest version. We have included a table of old options (Table B-2) just in case you encounter an old version of the shell.

Table B-1. Command-line options

Option	Meaning
-c string	Commands are read from string, if present. Any arguments after string are interpreted as positional parameters, starting with $0.
-D	A list of all double-quoted strings preceded by $ is printed on the standard ouput. These are the strings that are subject to language translation when the current locale is not C or POSIX. This also turns on the -n option.
-i	Interactive shell. Ignores signals TERM, INT, and QUIT. With job control in effect, TTIN, TTOU, and TSTP are also ignored.
-l	Makes bash act as if invoked as a login shell.
-o option	Takes the same arguments as set -o.
-O, +O shopt-option	shopt-option is one of the shell options accepted by the shopt builtin. If shopt-option is present, -O sets the value of that option; +O unsets it. If shopt-option is not supplied, the names and values of the shell options accepted by shopt are printed on the standard output. If the invocation option is +O, the output is displayed in a format that may be reused as input.
-s	Reads commands from the standard input. If an argument is given to bash, this flag takes precedence (i.e., the argument won't be treated as a script name and standard input will be read).
-r	Restricted shell. See Chapter 10.
-v	Prints shell input lines as they're read.
-	Signals the end of options and disables further option processing. Any options after this are treated as filenames and arguments. � is synonymous with -.
�debugger	Arranges for the debugger profile to be executed before the shell starts. Turns on extended debugging mode and shell function tracing.[2]
�dump-strings	Does the same as -D.
�dump-po-strings	Does the same as -D but the output is in the GNU gettext po (portable object) file format.
�help	Displays a usage message and exits.
�login	Makes bash act as if invoked as a login shell. Same as -l.
�noediting	Does not use the GNU readline library to read command lines if interactive.
�noprofile	Does not read the startup file /etc/profile or any of the personal initialization files.
�norc	Does not read the initialization file ~/.bashrc if the shell is interactive. This is on by default if the shell is invoked as sh.
�posix	Changes the behavior of bash to follow the POSIX guidelines more closely where the default operation of bash is different.
�quiet	Shows no information on shell startup. This is the default.
�rcfile file, �init-file file	Executes commands read from file instead of the initialization file ~/.bashrc, if the shell is interactive.
�verbose	Equivalent to -v.
�version	Shows the version number of this instance of bash and then exits.

^[2] Only available in bash version 3.0 and later.

Table B-2. Old command-line options

Option	Meaning
-c string	Commands are read from string, if present. Any arguments after string are interpreted as positional parameters, starting with $0.
-i	Interactive shell. Ignores signals TERM, INT, and QUIT. With job control in effect, TTIN, TTOU, and TSTP are also ignored.
-s	Reads commands from the standard input. If an argument is given to bash, this flag takes precedence (i.e., the argument won't be treated as a script name and standard input will be read).
-r	Restricted shell. See Chapter 10.
-	Signals the end of options and disables further option processing. Any options after this are treated as filenames and arguments. � is synonymous with -.
-norc	Does not read the initialization file ~/.bashrc if the shell is interactive. This is on by default if the shell is invoked as sh.
-noprofile	Does not read the startup file /etc/profile or any of the personal initialization files.
-rcfile file	Executes commands read from file instead of the initialization file ~/.bashrc, if the shell is interactive.
-version	Shows the version number of this instance of bash when starting.
-quiet	Shows no information on shell startup. This is the default.
-login	Makes bash act as if invoked as a login shell.
-nobraceexpansion	Does not perform curly brace expansion.
-nolineediting	Does not use the GNU readline library to read command lines if interactive.
-posix	Changes the behavior of bash to follow the POSIX guidelines more closely where the default operation of bash is different.