How to Terminate a Script

In a Bash script, how can I exit the entire script if a certain condition occurs?

Try this statement:

exit 1

Replace 1 with appropriate error codes. See also Exit Codes With Special Meanings.

How to terminate the script in JavaScript?

JavaScript equivalent for PHP's die. BTW it just calls exit() (thanks splattne):

function exit( status ) {
    // http://kevin.vanzonneveld.net
    // +   original by: Brett Zamir (http://brettz9.blogspot.com)
    // +      input by: Paul
    // +   bugfixed by: Hyam Singer (http://www.impact-computing.com/)
    // +   improved by: Philip Peterson
    // +   bugfixed by: Brett Zamir (http://brettz9.blogspot.com)
    // %        note 1: Should be considered expirimental. Please comment on this function.
    // *     example 1: exit();
    // *     returns 1: null

    var i;

    if (typeof status === 'string') {
        alert(status);
    }

    window.addEventListener('error', function (e) {e.preventDefault();e.stopPropagation();}, false);

    var handlers = [
        'copy', 'cut', 'paste',
        'beforeunload', 'blur', 'change', 'click', 'contextmenu', 'dblclick', 'focus', 'keydown', 'keypress', 'keyup', 'mousedown', 'mousemove', 'mouseout', 'mouseover', 'mouseup', 'resize', 'scroll',
        'DOMNodeInserted', 'DOMNodeRemoved', 'DOMNodeRemovedFromDocument', 'DOMNodeInsertedIntoDocument', 'DOMAttrModified', 'DOMCharacterDataModified', 'DOMElementNameChanged', 'DOMAttributeNameChanged', 'DOMActivate', 'DOMFocusIn', 'DOMFocusOut', 'online', 'offline', 'textInput',
        'abort', 'close', 'dragdrop', 'load', 'paint', 'reset', 'select', 'submit', 'unload'
    ];

    function stopPropagation (e) {
        e.stopPropagation();
        // e.preventDefault(); // Stop for the form controls, etc., too?
    }
    for (i=0; i < handlers.length; i++) {
        window.addEventListener(handlers[i], function (e) {stopPropagation(e);}, true);
    }

    if (window.stop) {
        window.stop();
    }

    throw '';
}

How to terminate script from within expect script

I added the following to my code and it seems to work. If anyone has any critiques, please feel free to let me know what could be improved.

expect command:

expect <<-EOS
        #!/usr/bin/expect
        log_user 0
        set timeout $EXP_TIMEOUT
        puts "\nValidating Password...\n"
        spawn ssh -q -o ConnectTimeout=$SSH_TIMEOUT -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null ${hostname}
        expect "*assword*"
        send -- "$secret\r"
        expect {
                "*assword*" {
                        send \x03
                        puts "\nIncorrect Password\n"
                        exit 1
                }
                "$prompt" {
                        send -- "exit\r"
                        puts "\nPassword Validated\n"
                }
        }
        expect eof
        exit 0
EOS

Parent Bash Script:

if [ $? == 1 ] 
then 
echo "Password validation failed. Exiting..."
exit
fi

How to terminate the script started with subprocess.Popen() based on specific condition

UPDATED
The easiest way to perform this is to pass the termination condition as a parameter to test.py.

Otherwise, you can use printing and reading from stdout and stdin If you want to preserve the output and still use Popen, see below. As an example, consider a simple test.py that calculates (in a very inefficient way) some primes:

test.py

import time

primes = [2, 3]

if __name__ == "__main__":
    for p in primes:
        print(p, flush=True)

    i = 5
    while True:
        for p in primes:
            if i % p == 0:
                break
        if i % p:
            primes.append(i)
            print(i, flush=True)
        i += 2
        time.sleep(.005)

You can read the output and choose to terminate the process when you achieve the desired output. As an example, I want to get primes up to 1000.

import subprocess

proc = subprocess.Popen("python test.py",
                        stdout=subprocess.PIPE, stdin=subprocess.PIPE,
                        bufsize=1, universal_newlines=True,
                        shell=True, text=True)
must_stop = False
primes = []
while proc.poll() is None:
    line = proc.stdout.readline()
    if line:
        new_prime = int(line)
        primes.append(new_prime)
        if  new_prime > 1000:
            print("Threshold achieved", line)
            proc.terminate()
        else:
            print("new prime:", new_prime)
print(primes)

please notice that since there is a delay in the processing and communication, you might get one or two more primes than desired. If you want to avoid that, you'd need bi-directional communication and test.py would be more complicated. If you want to see the output of test.py on screen, you can print it and then somehow parse it and check if the condition is fulfilled. Other options include using os.mkfifo (Linux only, not very difficult), which provides an easy communication path between two processes:

os.mkinfo version

test.py

import time
import sys

primes = [2, 3]

if __name__ == "__main__":
    outfile = sys.stdout
    if len(sys.argv) > 1:
        try:
            outfile = open(sys.argv[1], "w")
        except:
            print("Could not open file")
    for p in primes:
        print(p, file=outfile, flush=True)
    i = 5
    while True:
        for p in primes:
            if i % p == 0:
                break
        if i % p:
            primes.append(i)
            print("This will be printed to screen:", i, flush=True)
            print(i, file=outfile, flush=True) # this will go to the main process
        i += 2
        time.sleep(.005)

main file

import subprocess
import os
import tempfile


tmpdir = tempfile.mkdtemp()
filename = os.path.join(tmpdir, 'fifo')  # Temporary filename
os.mkfifo(filename)  # Create FIFO
proc = subprocess.Popen(["python3", "test.py", filename], shell=False)
with open(filename, 'rt', 1) as fifo:
    primes = []
    while proc.poll() is None:
        line = fifo.readline()
        if line:
            new_prime = int(line)
            primes.append(new_prime)
            if new_prime > 1000:
                print("Threshold achieved", line)
                proc.terminate()
            else:
                print("new prime:", new_prime)
    print(primes)

    pass

os.remove(filename)
os.rmdir(tmpdir)

How to terminate infinite execution of command inside script automatically?

You can use the timeout shell command to exit the command and start executing the next lines in case the command takes more time than the time specified in the timeout value.

...
timeout 100 ./myProgram 2>> log.txt > stars.txt
...

In the above program your ./myProgram will exit if it takes more than 100 seconds.

How do I terminate a script?

import sys
sys.exit()

details from the sys module documentation:

sys.exit([arg])
Exit from Python. This is implemented by raising the
SystemExit exception, so cleanup actions specified by finally clauses
of try statements are honored, and it is possible to intercept the
exit attempt at an outer level.
The optional argument arg can be an integer giving the exit status
(defaulting to zero), or another type of object. If it is an integer,
zero is considered “successful termination” and any nonzero value is
considered “abnormal termination” by shells and the like. Most systems
require it to be in the range 0-127, and produce undefined results
otherwise. Some systems have a convention for assigning specific
meanings to specific exit codes, but these are generally
underdeveloped; Unix programs generally use 2 for command line syntax
errors and 1 for all other kind of errors. If another type of object
is passed, None is equivalent to passing zero, and any other object is
printed to stderr and results in an exit code of 1. In particular,
sys.exit("some error message") is a quick way to exit a program when
an error occurs.
Since exit() ultimately “only” raises an exception, it will only exit
the process when called from the main thread, and the exception is not
intercepted.

Note that this is the 'nice' way to exit. @glyphtwistedmatrix below points out that if you want a 'hard exit', you can use os._exit(*errorcode*), though it's likely os-specific to some extent (it might not take an errorcode under windows, for example), and it definitely is less friendly since it doesn't let the interpreter do any cleanup before the process dies. On the other hand, it does kill the entire process, including all running threads, while sys.exit() (as it says in the docs) only exits if called from the main thread, with no other threads running.

Terminating a script in PowerShell

You should use the exit keyword.

Any way to exit bash script, but not quitting the terminal

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.