Re: The best way to know it is in zsh or bash

Re: The best way to know it is in zsh or bash

[Stephane Chazelas]

2019-09-06 09:41:22 -0500, Peng Yu:
> Suppose that I start with bash default login shell, then I call zsh.
> 
> I'd like to determine whether I am in bash or zsh. I see ZSH_*
> environment variables. Is ZSH_VERSION the most appropriate to be used
> to test whether it is in zsh or not? Thanks.
> 
> $ declare -p BASH_VERSION
> declare -- BASH_VERSION="5.0.0(1)-release"
> $ declare -p ZSH_VERSION
> typeset ZSH_VERSION=5.6.2
[...]

Just run ps or maybe ps -H (HP/UX, procps):

~$ ps -H
  PID TTY          TIME CMD
32057 pts/13   00:00:00 zsh
32123 pts/13   00:00:00   ps
~$ bash
bash-4.4$ ps -H
  PID TTY          TIME CMD
32057 pts/13   00:00:00 zsh
32124 pts/13   00:00:00   bash
32125 pts/13   00:00:00     ps

ps -o comm= -p "$$"

Will show you the name of the process of id $$ (the pid that executed the
shell).

-- 
Stephane

The best way to know it is in zsh or bash

[Peng Yu]

Suppose that I start with bash default login shell, then I call zsh.

I'd like to determine whether I am in bash or zsh. I see ZSH_*
environment variables. Is ZSH_VERSION the most appropriate to be used
to test whether it is in zsh or not? Thanks.

$ declare -p BASH_VERSION
declare -- BASH_VERSION="5.0.0(1)-release"
$ declare -p ZSH_VERSION
typeset ZSH_VERSION=5.6.2

-- 
Regards,
Peng

Re: The best way to know it is in zsh or bash

[René Wilhelm]

[-- Attachment #1: Type: text/plain, Size: 498 bytes --]

basename $SHELL

On Fri, 6 Sep 2019 at 16:41, Peng Yu <pengyu.ut@gmail.com> wrote:

> Suppose that I start with bash default login shell, then I call zsh.
>
> I'd like to determine whether I am in bash or zsh. I see ZSH_*
> environment variables. Is ZSH_VERSION the most appropriate to be used
> to test whether it is in zsh or not? Thanks.
>
> $ declare -p BASH_VERSION
> declare -- BASH_VERSION="5.0.0(1)-release"
> $ declare -p ZSH_VERSION
> typeset ZSH_VERSION=5.6.2
>
> --
> Regards,
> Peng
>

Re: The best way to know it is in zsh or bash

[Peng Yu]

> basename $SHELL

This doesn't work.

$ declare -p BASH_VERSION
declare -- BASH_VERSION="5.0.0(1)-release"
$ zsh
$ declare -p SHELL
export SHELL=/usr/local/bin/bash

-- 
Regards,
Peng

Re: The best way to know it is in zsh or bash

[gi1242+zsh]

For me

    echo $0
    
shows bash / zsh / dash as appropriate.

GI

-- 
When I read about the evils of drinking, I gave up reading.

Re: The best way to know it is in zsh or bash

[Mikael Magnusson]

On 9/6/19, Peng Yu <pengyu.ut@gmail.com> wrote:
> Suppose that I start with bash default login shell, then I call zsh.
>
> I'd like to determine whether I am in bash or zsh. I see ZSH_*
> environment variables. Is ZSH_VERSION the most appropriate to be used
> to test whether it is in zsh or not? Thanks.
>
> $ declare -p BASH_VERSION
> declare -- BASH_VERSION="5.0.0(1)-release"
> $ declare -p ZSH_VERSION
> typeset ZSH_VERSION=5.6.2

autotools configure does this, so presumably it works fairly universally,
if test -n "${ZSH_VERSION+set}" && (emulate sh) >/dev/null 2>&1; then :


-- 
Mikael Magnusson

Re: The best way to know it is in zsh or bash

[Bart Schaefer]

On Fri, Sep 6, 2019 at 7:42 AM Peng Yu <pengyu.ut@gmail.com> wrote:
>
> Suppose that I start with bash default login shell, then I call zsh.
>
> I'd like to determine whether I am in bash or zsh.

Where/when is it that you want to do this?  The two shells have an
entirely distinct set of startup files (except that many packaged
distributions have /etc/zshrc loading /etc/bashrc or similar) so I
take it that it's sometime after that?

> I see ZSH_*
> environment variables. Is ZSH_VERSION the most appropriate to be used
> to test whether it is in zsh or not?

The ZSH_* variables are normally global shell parameters, not exported
to the environment.  If something is exporting them, it probably
should not be.

ZSH_VERSION is the oldest of these (if you are worried about
differences within zsh itself), so it should be OK to examine.  See
Mikael's answer.