How to run interactive bash command from Emacs?

Question

I have a command my_cmd that is aliased to another command in my ~/.bashrc. From Perl and Python, I can run this command as bash -ic "my_cmd" (this also works from the terminal window, but here it is not necessary, and I can simply type my_cmd since bash already has loaded my ~/.bashrc). When I try this from Emacs:

(print (shell-command-to-string "bash -ic 'my_cmd'") (current-buffer)))

I get error:

bash: cannot set terminal process group (-1): Inappropriate ioctl for device
bash: no job control in this shell

I am running Emacs 24.3.1 on Ubuntu 14.04.

Answer 1

I tried it as well. I got the errors, but I got the output of the command, too. So, a partial solution would be to redirect the errors away:

(print (shell-command-to-string "bash -ic 'my_cmd' 2>/dev/null")
       (current-buffer))

Including the redirection inside single quotes doesn't help, because it's the outer bash that reports the problems, not the command.

Answer 2

A solution seems to be to use a login shell instead of interactive shell, according to the following answer on stackoverflow: running-system-command-under-interactive-bash-shell.

First make sure ~/.bash_profile contains:

if [ -f ~/.bashrc ]; then
    shopt -s expand_aliases
    . ~/.bashrc
fi

You can now use bash -lc instead of bash -ic:

(print (shell-command-to-string "bash -lc 'my_cmd'") (current-buffer)))

Answer 3

ok so i don't know how the whole thing works. i'll try to find out interactively

googling job control gives me http://www.gnu.org/software/libc/manual/html_node/Job-Control.html#Job-Control and https://stackoverflow.com/questions/11821378/what-does-bashno-job-control-in-this-shell-mean

so what exactly does "shell-command-to-string" do? C-h f shell-command-to-string RET Then I click on the link to the file to get me source code. (Ch-f = M-x describe-function)

(defun shell-command-to-string (command)
  "Execute shell command COMMAND and return its output as a string."
  (with-output-to-string
    (with-current-buffer
      standard-output
      (process-file shell-file-name nil t nil shell-command-switch command))))

what is "shell-file-name", you have to check by your place but for me C-h v shell-file-name RET returns "bash". (C-h v is M-x describe-variable)

and for me shell-command-switch is "-c". So no -i be default.

[WRONG]So by default you start an interactive bash in a non interactive bash. So yeah, doesn't work. I don't know much about the whole thing so can't tell you how to fix it. Maybe changing shell-command-switch would help, I'd try that out. Maybe it opens a whole another can of worms ^^![WRONG]

edit:

well actually I was quite wrong!

bash -c "bash -ic 'll'" (with ll aliased to ls -l in .bashrc) actually works!

So I guess I'd need to know what you tried to run to test it at home :)