Invoking the Shell

The command interpreter for bash can be invoked as follows:

bash [options] [arguments]

bash can execute commands from a terminal (when -i is specified), from a file (when the first argument is an executable script), or from standard input (if no arguments remain or if -s is specified).

Options

Options that appear here with double hyphens also work when entered with single hyphens, but the double-hyphen versions are recommended because they are standard.

• -, --
• Treat all subsequent strings as arguments, not options.
• --dump-po-strings
• Same as --dump-strings but uses a special "portable object" format suitable for scripting.
• --dump-strings
• For execution in non-English locales, dump all strings that bash translates.
• -c str
• Read commands from string str.
• -i
• Create an interactive shell (prompt for input).
• --help
• Print information about which version of bash is installed, plus a list of options.
• --login
• Behave like a login shell; try to process /etc/profile on startup. Then process ~/.bash_profile, ~/.bash_login, or ~/.profile (searching for each file only if the previous file is not found).
• --nobraceexpansion
• Disable brace expansion.
• --noediting
• Disable line editing with arrow and control keys.
• --noprofile
• Do not process /etc/profile, ~/.bash_profile, ~/.bash_login, or ~/.profile on startup.
• --norc
• Do not process ~/.bashrc on startup.
• -p
• Start up as a privileged user; don't process $HOME/.profile.
• --posix
• Conform to POSIX standard.
• -r
• Restrict users to a very secure, limited environment; for instance, they cannot change out of the startup directory or use the > sign to redirect output.
• --rcfile file
• Substitute file for bashrc on startup.
• --restricted
• Same as -r.
• -s
• Read commands from standard input; output from built-in commands goes to file descriptor 1; all other shell output goes to file descriptor 2.
• -v
• Print each line as it is executed (useful for tracing scripts).
• --verbose
• Same as -v.
• --version
• Print information about which version of bash is installed.
• -x
• Turn on debugging, as described under the -x option to the set built-in command.
• -D
• For execution in non-English locales, dump all strings that bash translates.

The remaining options to bash are listed under the set built-in command.

Arguments

Arguments are assigned, in order, to the positional parameters $1, $2, and so forth. If the first argument is an executable script, commands are read from it and remaining arguments are assigned to $1, $2, and so on.