Shells¶

Each shell represents a command-line interpreter, and is associated with:

a unique shell ID
a human-readable name
an icon (emoji / unicode character)
a detection function
various metadata in its info() method

Shell usage¶

Each shell is materialized by a Shell object, from which you can access various metadata:

>>> from extra_platforms import BASH
>>> BASH
Shell(id='bash', name='Bash')
>>> BASH.id
'bash'
>>> BASH.current
False
>>> BASH.info()
{'id': 'bash', 'name': 'Bash', 'icon': '＃', 'url': 'https://www.gnu.org/software/bash/', 'current': False, 'version': None, 'path': None}

To check if the current environment is running in a specific shell, use the corresponding detection function:

>>> from extra_platforms import is_bash
>>> is_bash()
False

The current shell can be obtained via the current_shell() function:

>>> from extra_platforms import current_shell
>>> current_shell()
Shell(id='unknown_shell', name='Unknown shell')

Symlink resolution: implementation over interface¶

Shell detection resolves symlinks in the SHELL environment variable before identifying the shell. This means detection always reports the concrete shell implementation rather than the POSIX interface name.

On most modern Unix systems, /bin/sh is a symlink to a concrete shell:

Distribution	`/bin/sh` target
Debian, Ubuntu	`/bin/dash`
Fedora, RHEL	`/bin/bash`
Alpine	`/bin/busybox`
macOS	`/bin/bash`

When /bin/sh symlinks to /bin/bash:

is_bash() returns True (the actual binary running is bash).
is_sh() returns False (the resolved binary is not sh).
is_bourne_shells() returns True (bash is a Bourne-compatible shell).

This design gives developers the most precise information about what binary is executing their code. If you need to check whether the shell provides a Bourne-compatible interface (regardless of which binary implements it), test against the BOURNE_SHELLS group with is_bourne_shells() instead of individual shell functions.

Recognized shells¶

Icon	Symbol	Name	Detection function
🪶	`ASH`	Almquist Shell	`is_ash()`
＃	`BASH`	Bash	`is_bash()`
▶	`CMD`	Command Prompt	`is_cmd()`
𝐂	`CSH`	C shell	`is_csh()`
💨	`DASH`	Dash	`is_dash()`
🐟	`FISH`	Fish	`is_fish()`
𝐊	`KSH`	Korn shell	`is_ksh()`
𝜈	`NUSHELL`	Nushell	`is_nushell()`
🔷	`POWERSHELL`	PowerShell	`is_powershell()`
𝐒	`SH`	Bourne Shell	`is_sh()`
𝐓	`TCSH`	tcsh	`is_tcsh()`
🐍	`XONSH`	Xonsh	`is_xonsh()`
ℤ	`ZSH`	Zsh	`is_zsh()`

Hint

The UNKNOWN_SHELL trait represents an unrecognized shell. It is not included in the ALL_SHELLS group, and will be returned by current_shell() if the current shell is not recognized.

Groups of shells¶

Icon	Symbol	Description	Detection	`Canonical`
🐚	`ALL_SHELLS`	All shells	`is_any_shell()`
💲	`BOURNE_SHELLS`	Bourne-compatible shells	`is_bourne_shells()`	⬥
🅲	`C_SHELLS`	C shells	`is_c_shells()`	⬥
◇	`OTHER_SHELLS`	Other shells	`is_other_shells()`	⬥
⌨️	`WINDOWS_SHELLS`	Windows shells	`is_windows_shells()`	⬥

Hint

Canonical groups are non-overlapping groups that together cover all recognized traits. They are marked with a ⬥ icon in the table above.

Other groups are provided for convenience, but overlap with each other or with canonical groups.

        ---
config:
  sankey:
    height: 800
    showValues: false
    width: 800

---
sankey-beta

ALL_SHELLS,BOURNE_SHELLS,6
ALL_SHELLS,OTHER_SHELLS,3
ALL_SHELLS,WINDOWS_SHELLS,2
ALL_SHELLS,C_SHELLS,2
BOURNE_SHELLS,ASH,1
BOURNE_SHELLS,BASH,1
BOURNE_SHELLS,DASH,1
BOURNE_SHELLS,KSH,1
BOURNE_SHELLS,SH,1
BOURNE_SHELLS,ZSH,1
OTHER_SHELLS,FISH,1
OTHER_SHELLS,NUSHELL,1
OTHER_SHELLS,XONSH,1
WINDOWS_SHELLS,CMD,1
WINDOWS_SHELLS,POWERSHELL,1
C_SHELLS,CSH,1
C_SHELLS,TCSH,1

        ---
config:
  mindmap:
    padding: 5

---
mindmap
    ((🐚 ALL_SHELLS))
        )⌨️ WINDOWS_SHELLS(
            (▶ CMD)
            (🔷 POWERSHELL)
        )◇ OTHER_SHELLS(
            (🐟 FISH)
            (𝜈 NUSHELL)
            (🐍 XONSH)
        )🅲 C_SHELLS(
            (𝐂 CSH)
            (𝐓 TCSH)
        )💲 BOURNE_SHELLS(
            (🪶 ASH)
            (＃ BASH)
            (💨 DASH)
            (𝐊 KSH)
            (𝐒 SH)
            (ℤ ZSH)

Predefined shells¶

Shell definitions and metadata.

extra_platforms.ASH = Shell(id='ash', name='Almquist Shell')¶

ID: ash
Aliases: -
Name: Almquist Shell
Icon: 🪶
Reference: <https://en.wikipedia.org/wiki/Almquist_shell>_
Detection function: is_ash()
Pytest decorators: @skip_ash / @unless_ash
Groups (3): ALL_SHELLS, ALL_TRAITS, BOURNE_SHELLS ⬥

extra_platforms.BASH = Shell(id='bash', name='Bash')¶

ID: bash
Aliases: -
Name: Bash
Icon: ＃
Reference: <https://www.gnu.org/software/bash/>_
Detection function: is_bash()
Pytest decorators: @skip_bash / @unless_bash
Groups (3): ALL_SHELLS, ALL_TRAITS, BOURNE_SHELLS ⬥

extra_platforms.CMD = Shell(id='cmd', name='Command Prompt')¶

ID: cmd
Aliases: -
Name: Command Prompt
Icon: ▶
Reference: <https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/cmd>_
Detection function: is_cmd()
Pytest decorators: @skip_cmd / @unless_cmd
Groups (3): ALL_SHELLS, ALL_TRAITS, WINDOWS_SHELLS ⬥

extra_platforms.CSH = Shell(id='csh', name='C shell')¶

ID: csh
Aliases: -
Name: C shell
Icon: 𝐂
Reference: <https://en.wikipedia.org/wiki/C_shell>_
Detection function: is_csh()
Pytest decorators: @skip_csh / @unless_csh
Groups (3): ALL_SHELLS, ALL_TRAITS, C_SHELLS ⬥

extra_platforms.DASH = Shell(id='dash', name='Dash')¶

ID: dash
Aliases: -
Name: Dash
Icon: 💨
Reference: <https://en.wikipedia.org/wiki/Almquist_shell#dash>_
Detection function: is_dash()
Pytest decorators: @skip_dash / @unless_dash
Groups (3): ALL_SHELLS, ALL_TRAITS, BOURNE_SHELLS ⬥

extra_platforms.FISH = Shell(id='fish', name='Fish')¶

ID: fish
Aliases: -
Name: Fish
Icon: 🐟
Reference: <https://fishshell.com>_
Detection function: is_fish()
Pytest decorators: @skip_fish / @unless_fish
Groups (3): ALL_SHELLS, ALL_TRAITS, OTHER_SHELLS ⬥

extra_platforms.KSH = Shell(id='ksh', name='Korn shell')¶

ID: ksh
Aliases: -
Name: Korn shell
Icon: 𝐊
Reference: <https://en.wikipedia.org/wiki/KornShell>_
Detection function: is_ksh()
Pytest decorators: @skip_ksh / @unless_ksh
Groups (3): ALL_SHELLS, ALL_TRAITS, BOURNE_SHELLS ⬥

extra_platforms.NUSHELL = Shell(id='nushell', name='Nushell')¶

ID: nushell
Aliases: -
Name: Nushell
Icon: 𝜈
Reference: <https://www.nushell.sh>_
Detection function: is_nushell()
Pytest decorators: @skip_nushell / @unless_nushell
Groups (3): ALL_SHELLS, ALL_TRAITS, OTHER_SHELLS ⬥

extra_platforms.POWERSHELL = Shell(id='powershell', name='PowerShell')¶

ID: powershell
Aliases: -
Name: PowerShell
Icon: 🔷
Reference: <https://learn.microsoft.com/en-us/powershell/>_
Detection function: is_powershell()
Pytest decorators: @skip_powershell / @unless_powershell
Groups (3): ALL_SHELLS, ALL_TRAITS, WINDOWS_SHELLS ⬥

extra_platforms.SH = Shell(id='sh', name='Bourne Shell')¶

ID: sh
Aliases: -
Name: Bourne Shell
Icon: 𝐒
Reference: <https://en.wikipedia.org/wiki/Bourne_shell>_
Detection function: is_sh()
Pytest decorators: @skip_sh / @unless_sh
Groups (3): ALL_SHELLS, ALL_TRAITS, BOURNE_SHELLS ⬥

extra_platforms.TCSH = Shell(id='tcsh', name='tcsh')¶

ID: tcsh
Aliases: -
Name: tcsh
Icon: 𝐓
Reference: <https://www.tcsh.org>_
Detection function: is_tcsh()
Pytest decorators: @skip_tcsh / @unless_tcsh
Groups (3): ALL_SHELLS, ALL_TRAITS, C_SHELLS ⬥

extra_platforms.UNKNOWN_SHELL = Shell(id='unknown_shell', name='Unknown shell')¶

ID: unknown_shell
Aliases: -
Name: Unknown shell
Icon: ❓
Reference: <https://en.wikipedia.org/wiki/Shell_(computing)>_
Detection function: is_unknown_shell()
Pytest decorators: @skip_unknown_shell / @unless_unknown_shell
Groups (2): ALL_TRAITS, UNKNOWN ⬥

extra_platforms.XONSH = Shell(id='xonsh', name='Xonsh')¶

ID: xonsh
Aliases: -
Name: Xonsh
Icon: 🐍
Reference: <https://xon.sh>_
Detection function: is_xonsh()
Pytest decorators: @skip_xonsh / @unless_xonsh
Groups (3): ALL_SHELLS, ALL_TRAITS, OTHER_SHELLS ⬥

extra_platforms.ZSH = Shell(id='zsh', name='Zsh')¶

ID: zsh
Aliases: -
Name: Zsh
Icon: ℤ
Reference: <https://www.zsh.org>_
Detection function: is_zsh()
Pytest decorators: @skip_zsh / @unless_zsh
Groups (3): ALL_SHELLS, ALL_TRAITS, BOURNE_SHELLS ⬥