Shell – spawn a new terminal that is a clone of the current terminal

environment-variablesshellterminal

So let's say I'm developing code in directory /asdf/qwer/dfgh/wert/asdf/qwer and I've added about three more directories like that to my path and I have a bunch of arcane environment variables set. Then I realize that I really need another terminal open and set up in just this same way (although this need is not reoccurring so that I would just alter my .bashrc). Is there any command to open a new terminal window that is an exact clone of this one?

Best Answer

Cloning the path is easy if you can run your terminal program from the command line. Assuming you're using xterm, just run xterm & from the prompt of the terminal you want to clone. The new xterm will start in the same directory, unless you have it configured to start as a login shell. Any exported environment variables will also carry over, but un-exported variables will not.

A quick and dirty way to clone the whole environment (including un-exported variables) is as follows:

# from the old shell:
set >~/environment.tmp

# from the new shell:
. ~/environment.tmp
rm ~/environment.tmp

If you've set any custom shell options, you'll have to reapply those as well.

You could wrap this whole process into an easily-runnable script. Have the script save the environment to a known file, then run xterm. Have your .bashrc check for that file, and source it and delete it if found.

Alternately, if you don't want to start one terminal from another, or just want more control, you could use a pair of functions that you define in .bashrc:

putstate () {
    declare +x >~/environment.tmp
    declare -x >>~/environment.tmp
    echo cd "$PWD" >>~/environment.tmp
}

getstate () {
    . ~/environment.tmp
}

EDIT: Changed putstate so that it copies the "exported" state of the shell variables, so as to match the other method. There are other things that could be copied over as well, such as shell options (see help set) -- so there is room for improvement in this script.

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Yes, all you need to know is the process id (PID) of the process. You can find this with the ps command, or the pidof command.

kill $(pidof ping)

Should work from any other shell. If it doesn't, you can use ps and grep for ping.

How to run a command in a new terminal window in the same process as the original

When you run a new terminal emulator, that creates a new terminal (/dev/pts/NUMBER on Linux). A program doesn't have to be started by that terminal to output there (try running tty in a terminal, then in another terminal run echo hello >/dev/pts/NUMBER). So you can tell your Python script to read and write from the terminal; all you need is to find out the path to the device file.

With xterm, it's pretty easy: run xterm -e 'tty >&3; myCommand' with file descriptor 3 connected to a pipe from which your program reads the path to the terminal device.

p = subprocess.Popen("xterm -e 'tty >&3; exec sleep 99999999' 3>&1",
                     shell=True, stdout=subprocess.PIPE)
tty_path = readline(p.stdout)
tty = open(tty_path, 'r+')

Your Python program can now read and write to tty. When you've finished, kill the terminal emulator (os.kill(p.pid, signal.SIGTERM)).

With a terminal emulator that's based on a single process for multiple windows such as xfce4-terminal, what you want to do is considerably harder. Running xfce4-terminal breaks links between the parent process and the child of the terminal emulator, and doesn't give you a nice PID that you can kill. You could use a named pipe to communicate but it's a bot harder to set up.

Best Answer

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