How can I check if the current shell is being used from vim?

Question

I am running OS X. On vim, if you do the :sh command, you can drop to a shell to execute commands. I constantly forget whether I am in this shell or not.

Is there any way to check if I am in the shell coming from vim?

Answer 1

env | grep vim lists environment variables that vim passes to your shell. I doubt VIMRUNTIME is defined if you haven't started your shell from vim.

Answer 2

I type ps (without any options) and see if vim is listed.

Answer 3

You can look at the command name of the shell's parent process: ps -o comm= -p $PPID. You could for example change your prompt to include the parent process id.

Furthermore, if you only want to change your prompt in shells that are not running directly inside a terminal emulator, you can test this by checking whether the shell's controlling terminal is the same as its parent process's. If the parent is a terminal emulator, it won't have its own terminal as a controlling terminal.

For example, if you put the following lines in your ~/.kshrc or ~/.bashrc or ~/.zshrc (pick the one appropriate for your shell), your prompt will begin with {vim} if the shell is running under vim:

parent_command=$(ps -o comm= -p $PPID)
parent_command=${parent_command##*/}
if [ "$(ps -o tty= -p $$)" = "$(ps -o tty= -p $PPID)" ]; then
  # Not running directly under a terminal emulator
  PS1="{$parent_command}$PS1"
fi

You may also be interested in some of the discussion on How to know the “level” of shells I am in?.

Answer 4

You could use MacVim (http://code.google.com/p/macvim/). Whether or not your shell came from a vim instance becomes pretty obviously since your shell is in a MacVim window and not a Terminal window.