If a file `~/.emacs_SHELLNAME' exists, or `~/.emacs.d/init_SHELLNAME.sh',
it is given as initial input (but this may be lost, due to a timing
error, if the shell discards input when it starts up).
The buffer is put in Shell mode, giving commands for sending input
and controlling the subjobs of the shell. See `shell-mode'.
See also the variable `shell-prompt-pattern'.