Bash should be run as a login shell

It looks like bash understands $SHELL but this shell is not a login shell which means people who have customized their $PROMPT_COMMAND in their Dotfiles end up with weird errors.

A couple of solutions I can think of.

1. Run bash with --login --interactive
2. Rather than just running $SHELL, you can run exec and source the virtualenv.
   • This has the added bonus of having the same virtualenv flow and running `deactivate.
   • Running Ctrl-D is error prone, I quit the shell thinking I’m inside pipenv shell many many times.

[jjangsangy]

Just read through some of the pew docs (that was helpful), so I’m looking right here in the troubleshoot section.

They recommend that you move your PATH declarations into ~/.profile and execute as a login shell.

Also, this table was really helpful me figure out why ~/.profile was not getting sourced

Mode	/etc/profile	~/.bash_profile	~/.bash_<span class="search_hit mark">login</span>	~/.profile	~/.bashrc	${ENV}
<span class="search_hit mark">Login</span> <span class="search_hit mark">shell</span>	X	X	X	X	-	-
Interactive Shell	-	-	-	-	X	-
SH compatible <span class="search_hit mark">login</span>	X	-	-	X	-	-
SH compatible	-	-	-	-	-	X
POSIX® compatiblity	-	-	-	-	-	X

[jjangsangy]

After reading the pew docs and combing deep caverns of shell scripting lore I discovered that functions can be exported (who knew that was a thing!).

function export example

So let’s say I have function that fork bombs your shell and I want to hot potato it into a child shell processes.

$ function forking { forking | forking & }
$ pipenv shell
$ foobar
bash: foobar: command not found

Keep forking to a minimum

Bash prevents child processes from cases of unprotected forking somtimes…. You need to explicitly flag functions using export -f foobar or declare -fx foobar.

$ declare -F
declare -fx powerline_precmd

Environment is copy by value

Even if the functions are bound to environment variables that are themselves exported, the new sub shell is passed a new copy of the functions and not a reference.

A good example is ${PROMPT_COMMAND} which is usually bound to a function that populates the variable. That function will get called every time $PS1 is displayed so make sure to export it.

function powerline_precmd() {
     export PS1="$(powerline-shell 2> /dev/null)"
}
declare -fx powerline_precmd
export PROMPT_COMMAND="powerline_precmd"