Is it possible to specify the bash prompt using a command-line option?

Question

I use vim a lot and often find it useful to drop into the command line using !bash. However, I need to type exit to return to vim and sometimes I'm not sure whether I'm in a subshell or whether that will close my session.

What I'd really like to do is type something like !bash -prompt "subshell" so that I get something like this:

subshell$ <commands go here>

Is this possible?

Answer 1

The most direct way to do this is to set the PS1 environment variable within vim:

:let $PS1="subshell$ "

And start your sub-shells using the command :shell instead of :!bash.

Using the $ sign with let modifies an environment variable. Add this to your .vimrc to persist the setting.

Alternately, using :shell you can specify a more specific command, including arguments, using the shell option, see help shell and help 'shell'.

So:

:set shell=bash\ --rcfile\ ~/.vimbashrc

In .vimbashrc add PS1="subshell ", and invoke the sub-shells using :shell instead of !bash. Add this to your .vimrc to persist the setting.

So you have two options:

• Add let $PS1="subshell " to your .vimrc, and start sub-shells using :shell instead of :!bash.
• Make a custom rc file for your vim sub-shells, add your specific PS1="subshell " to it, and modify the shell option in your .vimrc: set shell=bash\ --rcfile\ ~/.vimbashrc.

Finally, if you must use :!bash to start the sub-shells there are a couple of more options. Note that you can also pass a more specific command line using !, e.g.:

• :PS1="subshell$ " bash should work.
• :!bash\ --rcfile\ ~/.vimbashrc, and set PS1 in .vimbashrc as above

But you'll need to type these every time, or define a mapping for it.

Answer 2

Use shell variable $SHLVL seems to be another option here. Add $SHLVL in your $PS1:

export PS1="$PS1 $SHLVL"

so your prompt looks like this:

[tim@RackAblade47 ~]$ 2

when you start shell from VIM, $SHLVL will increase:

[tim@RackAblade47 ~]$ 4