bash

Run script

$ bash [script.sh]

$ bash -c ["echo hello"]

$ bash -l

$ echo "ls -la" | bash

$ bash -x [script.sh]

$ bash -n [script.sh]

bash [options] [file] [arguments]

bash (Bourne Again SHell) is a Unix shell and command language interpreter. It's the default shell on most Linux distributions and macOS, providing command execution, scripting, job control, and extensive programming features.
Bash is backward-compatible with the original Bourne shell (sh) while adding numerous improvements and modern features.

-c string

Execute command from string

Login shell (sources profile files)

Interactive mode

Print commands before execution (debug mode)

Syntax check only (no execution)

Exit on first error

Error on undefined variables

Verbose mode (print input lines)

Don't read profile files

Don't read ~/.bashrc

- Command history (readline)
- Tab completion
- Job control (fg, bg, jobs)
- Arithmetic evaluation
- Arrays and associative arrays
- Functions
- Pattern matching and globbing
- Process substitution
- Here documents
- Conditional execution
- Loops and flow control

Login shell

/etc/profile, ~/.bashprofile, ~/.bashlogin, ~/.profile

~/.bashrc

$BASH_ENV

$0 - Script name
$1, $2, ... - Positional parameters
$@ - All parameters
$# - Parameter count
$? - Exit status of last command
$$ - Process ID
$! - PID of last background job

Bash-specific features not portable to POSIX sh. Scripts should use `#!/bin/bash` not `#!/bin/sh`. Unquoted variables can cause word splitting. Use `shellcheck` to validate scripts.

Bash was created by Brian Fox for the GNU Project in 1989 as a free replacement for the Bourne shell, first released as version 0.99. Version 5.0 was released in 2019.

sh(1), zsh(1), shellcheck(1)