You can always try the obvious things like ^C, ^D (eof), Escape etc., but if all fails I usually end up suspending the command with ^Z (Control-Z) which puts me back into the shell.

I then do a ps command and note the PID (process id) of the command and then issue a kill thePID (kill -9 thePID if the former didn't work) command to terminate the application.

Note that this is not a tidy (no pun intended) way to terminate the application/command and you run the risk of perhaps no saving some data etc.

An example (I'd have used tidy but I don't have it installed):

$ gnuplot

    G N U P L O T
    Version 4.2 patchlevel 6 
     ....
    Send bug reports and suggestions to <http://sourceforge.net/projects/gnuplot>

Terminal type set to 'wxt'
gnuplot> 
gnuplot>               #####  typed ^Z here
[1]+  Stopped                 gnuplot
$ ps
  PID TTY          TIME CMD
 1681 pts/1    00:00:00 tcsh
 1690 pts/1    00:00:00 bash
 1708 pts/1    00:00:00 gnuplot
 1709 pts/1    00:00:00 ps


$ kill 1708            ###### didn't kill the command as ps shows

$ ps
  PID TTY          TIME CMD
 1681 pts/1    00:00:00 tcsh
 1690 pts/1    00:00:00 bash
 1708 pts/1    00:00:00 gnuplot
 1710 pts/1    00:00:00 ps
$ kill -9 1708           ### -9 did the trick
$ 
[1]+  Killed                  gnuplot

$ ps
  PID TTY          TIME CMD
 1681 pts/1    00:00:00 tcsh
 1690 pts/1    00:00:00 bash
 1711 pts/1    00:00:00 ps

Some things won't respond to Ctrl+C; in that case, you can also do Ctrl+Z which stops the process and then kill %1 - or even fg to go back to it. Read the section in man bash entitled "JOB CONTROL" for more information. It's very helpful. (If you're not familiar with man or the man pager, you can search using /. man bash then inside it /JOB CONTROLEnter will start searching, n will find the next match which is the right section.)

The "problem" really is that you're sourcing and not executing the script. When you source a file, its contents will be executed in the current shell, instead of spawning a subshell. So everything, including exit, will affect the current shell.

Instead of using exit, you will want to use return.

I think you are looking for traps:

trap terminate_foo SIGINT

terminate_foo() {
  echo "foo terminated"
  bar
}

foo() {
  while :; do 
    echo foo
    sleep 1
  done
}

bar() {
  while :; do 
    echo bar
    sleep 1
  done
}

foo

Output:

./foo
foo
foo
foo
^C foo terminated # here ctrl+c pressed
bar
bar
...

Function foo is executed until Ctrl+C is pressed, and then continues the execution, in this case the function bar.

There are a few keypresses that should help you here.

Ctrl+C should send the foreground process SIGINT, and that should terminate the process unless you trap the signal with something like trap INT ... in your shell code.

Ctrl+Z should send SIGSTOP, which would pause your process, again unless you trap your signals.

The mapping of key sequences jumps through some hoops, including terminal settings. What does stty -a say on your computer? Look in the output for intr, that's the keypress that should trigger SIGINT. If nothing is set, you need to set it, something like stty intr ^C

As others have said, you can kill the process from another window as well.

You can use the timeout command to run a command with a time limit. Its basic syntax is:

timeout DURATION COMMAND

where DURATION is a floating point number with the suffix s for seconds, m for minutes, h for hours or d for days and COMMAND is the command you wish to run.

In your case, you can use:

timeout 10s vlc -vvv http://10.0.0.113:8000/stream.mjpg --sout="#std{access=file,mux=ogg,dst=/home/whsrobotics/vlc_project/first_try.mp4}"

to run your command for 10 seconds and then kill it.

I've observed that using CtrlZ to shift the program to a background process does the trick.

foo && bar

Thanks to @Arkadiusz Drabczyk for pointing it in comments that foo; bar doesn't give control in the required way.

Then:

^Z

[1]+  Stopped                 foo

The command stops only the first task and

fg %1

This brings only task foo to the foreground and completes the task and exits.

PS: This can be checked with two scripts writing to a file. The first one sleeping for a few seconds to give time to be put back.

I'm lost on why the CtrlZ handles only the command running and leaves the rest. Would love to get to know.

To cancel execution of the command, completely erase the contents of the file before saving it and quitting the editor.

Interestingly, using this method, the original unedited command is still saved in the history.

Note: this answer was suggested in a comment -- I tested it and it works.

You have few options. One is to stop the script (CtrlZ), get the PID of the script and send SIGKILL to the process group.

When a command is executed in a shell, the process it starts and all its children are part of the same process group (in this case, the foreground process group). To send a signal to all processes in this group, you send it to the process leader. For the kill command, process leader is denoted thus:

kill -PID

Where PID is the process ID of the script.

Example:

Consider a script test.sh which launches some processes. Say you ran it in a shell:

$ ./test.sh

In another terminal,

$ pgrep test.sh
17802
$ pstree -ps `!!`
pstree -ps `pgrep test.sh`
init(1)───sshd(1211)───sshd(17312)───sshd(17372)───zsh(17788)───test.sh(17802)─┬─dd(17804)
                                                                               ├─sleep(17805)
                                                                               └─yes(17803)

In this case, to send a signal to process group created by test.sh, you'd do:

kill -INT -17802

-INT is used to send SIGINT, and so this command is the equivalent of pressing CtrlC on the terminal. To send SIGKILL:

kill -KILL -17802

You only need to stop the script if you can't open another terminal. If you can, use pgrep to find the PID.

One of the commands that the script launches may be trapping SIGINT, which is probably why CtrlC is ineffective. However, SIGKILL can't be trapped, and it is usually a last-resort option. You might want to try SIGTERM (-TERM) before going for the kill. Neither SIGKILL or SIGTERM can be set up as a keyboard shortcut the way SIGINT is.

All this is moot if your script doesn't contain a shebang line. From this SO answer:

Usually the parent shell guesses that the script is written for the the same shell (minimal Bourne-like shells run the script with /bin/sh, bash runs it as a bash subprocess) ...

Because of this, when the script is executed, you won't find a process named after script (or a process with the script's name in the command line) and pgrep will fail.

Always use a shebang line.