About
Bash is an sh-compatible a shell that executes commands read:
- from the standard input
- or from a file (script).
With docker, you can have a bash easily on unbutu with the following command
docker run -t -i ubuntu /bin/bash
Syntax
bash [multiple character options] [single character options] [arguments]
Single character Options
In addition to the single-character shell options documented in the description of the set builtin command, bash interprets the following options when it is invoked:
| Options | Short Description | Long Description |
|---|---|---|
| Command | ||
| -c string | String Command | commands are read from string. If there are arguments after the string, they are assigned to the positional parameters, starting with 0. |
| -s | Standard Input Command | If the -s option is present, or if no arguments remain after option processing, then commands are read from the standard input. This option allows the positional parameters to be set when invoking an interactive shell. |
| Others | ||
| -i | Interactive shell | |
| -l | Login Shell | |
| -r | Restricted | |
| -D | A list of all double-quoted strings preceded by $ is printed on the standard output. These are the strings that are subject to language translation when the current locale is not C or POSIX. This implies the -n option; no commands will be executed. | |
| [-+]O [shopt_option] | shopt invocation | shopt_option is one of the shell options accepted by the shopt builtin command. -O sets the value of that option; +O unsets it. |
| – | End of options processing | disables further option processing and treat further arguments as file names and arguments. An argument of - is equivalent to –. |
Multi-character Options
The multi-character options must appear on the command line before the single-character options to be recognized.
| Options | Short Description | Long Description |
|---|---|---|
| –debugger | Arrange for the debugger profile to be executed before the shell starts. Turns on extended debugging mode (see the description of the extdebug option to the shopt builtin below) and shell function tracing (see the description of the -o functrace option to the set builtin below). | |
| –dump-po-strings | Equivalent to -D with gettext po (portable object) | Equivalent to -D, but the output is in the GNU gettext po (portable object) file format. |
| –dump-strings | Equivalent to -D | |
| –help | Help | Display a usage message on standard output and exit successfully. |
| –init-file file | ||
| –rcfile file | Execute commands from file | instead of the standard personal initialization file ~/.bashrc if the shell is interactive |
| –login | Equivalent to -l | |
| –noediting | Do not use the GNU readline library | Do not use the GNU readline library to read command lines when the shell is interactive. |
| –noprofile | no startup script | Do not read either the system-wide startup file /etc/profile or any of the personal initialization files ~/.bash_profile, ~/.bash_login, or ~/.profile. By default, bash reads these files when it is invoked as a login shell |
| –norc | no personal initialization file | Do not read and execute the personal initialization file ~/.bashrc if the shell is interactive. This option is on by default if the shell is invoked as sh. |
| –posix | posix beahviour | Change the behavior of bash where the default operation differs from the POSIX standard to match the standard (posix mode). |
| –restricted | Restricted shell | The shell becomes restricted |
| –rpm-requires | List of required rpm files | This files are required for the shell script to run. |
| –verbose | Equivalent to -v | |
| –version | Version |
Arguments
File
If arguments remain after option processing, and neither the -c nor the -s option has been supplied, the first argument is assumed to be the name of a file containing shell commands.
If bash is invoked in this fashion, 0 is set to the name of the file, and the positional parameters are set to the remaining arguments. Bash reads and executes commands from this file, then exits.
An attempt is first made to open the file in the current directory, and, if no file is found, then the shell searches the directories in PATH for the script.