How to send control+c from a bash script?
BashGnu ScreenBash Problem Overview
I'm starting a number of screens in a bash script, then running django's runserver
command in each of them. I'd like to be able to programmatically stop them all as well, which requires me to send Control+c
to runserver
.
How can I send these keystrokes from my bash script?
Bash Solutions
Solution 1 - Bash
Ctrl+C sends a SIGINT
signal.
kill -INT <pid>
sends a SIGINT
signal too:
# Terminates the program (like Ctrl+C)
kill -INT 888
# Force kill
kill -9 888
Assuming 888
is your process ID.
Note that kill 888
sends a SIGTERM
signal, which is slightly different, but will also ask for the program to stop. So if you know what you are doing (no handler bound to SIGINT
in the program), a simple kill
is enough.
To get the PID of the last command launched in your script, use $!
:
# Launch script in background
./my_script.sh &
# Get its PID
PID=$!
# Wait for 2 seconds
sleep 2
# Kill it
kill $PID
Solution 2 - Bash
CTRL-C generally sends a SIGINT signal to the process so you can simply do:
kill -INT <processID>
from the command line (or a script), to affect the specific processID
.
I say "generally" because, as with most of UNIX, this is near infinitely configurable. If you execute stty -a
, you can see which key sequence is tied to the intr
signal. This will probably be CTRL-C but that key sequence may be mapped to something else entirely.
The following script shows this in action (albeit with TERM
rather than INT
since sleep
doesn't react to INT
in my environment):
#!/usr/bin/env bash
sleep 3600 &
pid=$!
sleep 5
echo ===
echo PID is $pid, before kill:
ps -ef | grep -E "PPID|$pid" | sed 's/^/ /'
echo ===
( kill -TERM $pid ) 2>&1
sleep 5
echo ===
echo PID is $pid, after kill:
ps -ef | grep -E "PPID|$pid" | sed 's/^/ /'
echo ===
It basically starts an hour-log sleep
process and grabs its process ID. It then outputs the relevant process details before killing the process.
After a small wait, it then checks the process table to see if the process has gone. As you can see from the output of the script, it is indeed gone:
===
PID is 28380, before kill:
UID PID PPID TTY STIME COMMAND
pax 28380 24652 tty42 09:26:49 /bin/sleep
===
./qq.sh: line 12: 28380 Terminated sleep 3600
===
PID is 28380, after kill:
UID PID PPID TTY STIME COMMAND
===
Solution 3 - Bash
kill -INT <pid>
are not exactly the same
ctrl+c and To emulate ctrl+c we need to first understand the difference.
kill -INT <pid>
will send the INT
signal to a given process (found with its pid
).
ctrl+c is mapped to the intr
special character which when received by the terminal should send INT
to the foreground process group of that terminal. You can emulate that by targetting the group of your given <pid>
. It can be done by prepending a -
before the <pid>
in the kill command. Hence the command you want is:
kill -INT -<pid>
You can test it pretty easily with a script:
#!/usr/bin/env ruby
fork {
trap(:INT) {
puts 'signal received in child!'
exit
}
sleep 1_000
}
puts "run `kill -INT -#{Process.pid}` in any other terminal window."
Process.wait
Sources:
Solution 4 - Bash
You can get the PID of a particular process like MySQL by using following commands: ps -e | pgrep mysql
This command will give you the PID of MySQL rocess. e.g, 13954 Now, type following command on terminal. kill -9 13954 This will kill the process of MySQL.
Solution 5 - Bash
pgrep -f process_name > any_file_name
sed -i 's/^/kill /' any_file_name
chmod 777 any_file_name
./any_file_name
for example 'pgrep -f firefox' will grep the PID of running 'firefox' and will save this PID to a file called 'any_file_name'. 'sed' command will add the 'kill' in the beginning of the PID number in 'any_file_name' file. Third line will make 'any_file_name' file executable. Now forth line will kill the PID available in the file 'any_file_name'. Writing the above four lines in a file and executing that file can do the control-C. Working absolutely fine for me.