I store in a variable an executed command like so:
pio device monitor -p COM22 -b 115200 --no-reconnect | grep -E -o -m 1 '[A-Za-z0-9]{12}'
pio device monitor is a command to watch custom logs from an esp32, I use these logs to extract the wanter value (something like C8F09E0AA13C).
I want to run this command in the background and when the command return something, kill the process.
The script works as expected. The command stored in IDFound run in the background and as soon it found something the loop stop and the process is killed and I get the wanted value.
# /bin/bash
regex='[A-Za-z0-9]{12}'
port=COM22
unset -v IDFound
if ! [[ $IDFound =~ $regex ]] ; then
echo 'Please press the reset button of the ESP-prog'
IDFound=$(pio device monitor -p $port -b 115200 --no-reconnect | grep -E -o -m 1 $regex &)
# Get PID of this command
pid=$(ps -ef | awk '/pio/{print $2}')
# kill the process with PID
kill $pid
fi
echo $IDFound
But my problem is that I get PID with the pio keyword and I run another similar command in my script. I don't want to kill the wrong process.
I want to get the PID with $! to avoid mistake. How could I achieve that ?
I am trying to kill a process using a shell script.Looks shell itself is getting killed in this process. Also I am seeing non zero return value of the script in terminal.
I am running it on Amazon Linux 2 with sudo.
#!/bin/bash
kill -9 $(ps -ef | grep myapp | grep -v grep | awk '{print $2}')
I am executing like:
sudo ./myscript.sh
"echo $?" after executing is returning 137 instead of zero. Can someone please help to understand what is going wrong.
Another observation:
if i directly run kill command in my terminal, i.e below command,
kill -9 $(ps -ef | grep myapp | grep -v grep | awk '{print $2}')
I see echo $? is returning zero.
Update:
Problem is solved. Name of process I am trying to kill is overlapping with name of my script. Hence grep is returning both the pid's. Both the process are getting killed. Also learnt that better way of doing this by using pkill or using pidof() to get pid.
If you want the exit code of your last-run command to be the exit code for the script, your script must end with exit $? as the last line. Any function before that must also end with the $? so the chain flows to that final line. Otherwise some other exit is taking place.
If the script is being killed along side the application or script you are trying to kill, then your ps and grep work is likely including both in the results. Look at the output of the ps and grep while the script is running. You could add a line prior to your kill line which just shows the output of the ps and greps so you can see what is actually getting killed.
Finally (and I don't think this is the case) if you are trying to end the script after the kill, manually run an exit (again likely using exit $? for the reason stated above) where appropriate within the script.
Hope that helps you get where you are going.
I wrote a script to run constantly on startup. If for whatever reason the script were to fail, I wrote a second script to check if it has failed, and if so, run the first script again. I then set this second script as a cronjob to run every minute so that it is constantly checking if the first script is alive.
So to test this, I reboot my system. I can see in htop that the first script is running from start up as expected. Good. I kill the process to test the second script. Sure enough, the second script starts the first script again. Still good. I then kill this process, but the second script won't run again now. It still updates a txt file when I manually start the first script, but the second script just doesn't start the first script like it's supposed to. Is it because I killed the cronjob? Restarting the cron service doesn't fix anything though, so I don't know why my second script isn't running again at all.
First script:
#!/bin/bash
stamp=$(date +%Y%m%d-%H%M)
timeout 10d tcpdump -i eth0 -s 96 -z gzip -C 10 -w /home/user/Documents/${stamp}
Second script:
#!/bin/bash
echo "not running" > /home/working.txt
if (( $(ps -ef | grep -v grep | grep tcpdump.sh | wc -l) > 0 ))
then
echo "tcpdump is running!!!" > /home/working.txt
else
/usr/local/bin/tcpdump.sh start
fi
Any help?
You would probably be better off running a simple for loop as the main script, and that kicks off the tcpdump script in the background, so something like:
#!/bin/bash
while true; do
if ps -ef | grep -v grep | grep -q tcpdump; then
: tcpdump running OK
else
# tcpdump not running - start it off
nohup /usr/local/bin/firstscript.sh start &
fi
sleep 30
done
This checks that "tcpdump.sh" is in the output of the "ps -ef" command - if it is, then do nothing (note that you must have an actual command between the "then" and "else" - the ":" command, which just takes it s arguments and ignores them, is sufficient). If it isn't running, start the first script in the background. Then sleep 30 seconds and check again. (Yes, I could have inverted the test so that I didn't need an empty "then" arm, but it would have made the code less obvious)
You put this script as the one which starts at boot time.
Edit: Do you really want to check for "tcpdump.sh"? Is that what the first script is actually called? Assuming that you actually want to check for the tcpdump program, you could use:
if pgrep tcpdump; then
I have a bash script that is supposed to check for a running instance of a program and if its not running execute a command (echo for testing purposes). The problem is, that bash isn't executing the command even though it works when I copy/paste the command directly to the command line. I imagine my issue is simple and caused by my naivety with the script language.
The line in question:
ps -ef | grep -v grep | grep $SCRIPT > /dev/null || echo "`date` - $0 : $SCRIPT stopped. Restarting..."
If I paste it to the command line it works perfect, but when I run my script nothing happens. Suggestions?
EDIT: I believe I've resolved the issue. The script that is run to check the queue_reader.sh script I foolishly named check_queue_reader.sh" so the ps -ef command was finding itself preventing the || from executing.
See edit on original post.
The script I was running was called "check_queue_reader.sh" and was using grep to search ps -ef for "queue_reader.sh". This caused the script to locate itself thus failing the check when it got to ||
Is there any way to set the process name of a shell script? This is needed for killing this script with the killall command.
Here's a way to do it, it is a hack/workaround but it works pretty good. Feel free to tweak it to your needs, it certainly needs some checks on the symbolic link creation or using a tmp folder to avoid possible race conditions (if they are problematic in your case).
Demonstration
wrapper
#!/bin/bash
script="./dummy"
newname="./killme"
rm -iv "$newname"
ln -s "$script" "$newname"
exec "$newname" "$#"
dummy
#!/bin/bash
echo "I am $0"
echo "my params: $#"
ps aux | grep bash
echo "sleeping 10s... Kill me!"
sleep 10
Test it using:
chmod +x dummy wrapper
./wrapper some params
In another terminal, kill it using:
killall killme
Notes
Make sure you can write in your current folder (current working directory).
If your current command is:
/path/to/file -q --params somefile1 somefile2
Set the script variable in wrapper to /path/to/file (instead of ./dummy) and call wrapper like this:
./wrapper -q --params somefile1 somefile2
You can use the kill command on a PID so what you can do is run something in the background, get its ID and kill it
PID of last job run in background can be obtained using $!.
echo test & echo $!
You cannot do this reliably and portably, as far as I know. On some flavors of Unix, changing what's in argv[0] will do the job. I don't believe there's a way to do that in most shells, though.
Here are some references on the topic.
Howto change a UNIX process and child process name by modifying argv0
Is there a way to change the effective process name in Python?
This is an extremely old post. Pretty sure the original poster got his/her answer long ago. But for newcomers, thought I'd explain my own experience (after playing with bash for a half hour). If you start a script by script name w/ something like:
./script.sh
the process name listed by ps will be "bash" (on my system). However if you start a script by calling bash directly:
/bin/bash script.sh
/bin/sh script.sh
bash script.sh
you will end up with a process name that contains the name of the script. e.g.:
/bin/bash script.sh
results in a process name of the same name. This can be used to mark pids with a specific script name. And, this can be useful to (for example) use the kill command to stop all processes (by pid) that have a process name containing said script name.
You can all use the -f flag to pgrep/pkill which will search the entire command line rather than just the process name. E.g.
./script &
pkill -f script
Include
#![path to shell]
Example for path to shell -
/usr/bin/bash
/bin/bash
/bin/sh
Full example
#!/usr/bin/bash
On Linux at least, killall dvb works even though dvb is a shell script labelled with #!. The only trick is to make the script executable and invoke it by name, e.g.,
dvb watch abc write game7 from 9pm for 3:30
Running ps shows a process named
/usr/bin/lua5.1 dvb watch ...
but killall dvb takes it down.
%1, %2... also do an adequate job:
#!/bin/bash
# set -ex
sleep 101 &
FIRSTPID=$!
sleep 102 &
SECONDPID=$!
echo $(ps ax|grep "^\(${FIRSTPID}\|${SECONDPID}\) ")
kill %2
echo $(ps ax|grep "^\(${FIRSTPID}\|${SECONDPID}\) ")
sleep 1
kill %1
echo $(ps ax|grep "^\(${FIRSTPID}\|${SECONDPID}\) ")
I put these two lines at the start of my scripts so I do not have to retype the script name each time I revise the script. It won't take $0 of you put it after the first shebang. Maybe someone who actually knows can correct me but I believe this is because the script hasn't started until the second line so $0 doesn't exist until then:
#!/bin/bash
#!/bin/bash ./$0
This should do it.
My solution uses a trivial python script, and the setproctitle package. For what it's worth:
#!/usr/bin/env python3
from sys import argv
from setproctitle import setproctitle
from subprocess import run
setproctitle(argv[1])
run(argv[2:])
Call it e.g. run-with-title and stick it in your path somewhere. Then use via
run-with-title <desired-title> <script-name> [<arg>...]
Run bash script with explicit call to bash (not just like ./test.sh). Process name will contain script in this case and can be found by script name. Or by explicit call to bash with full path as
suggested in display_name_11011's answer:
bash test.sh # explicit bash mentioning
/bin/bash test.sh # or with full path to bash
ps aux | grep test.sh | grep -v grep # searching PID by script name
If the first line in script (test.sh) explicitly specifies interpreter:
#!/bin/bash
echo 'test script'
then it can be called without explicit bash mentioning to create process with name '/bin/bash test.sh':
./test.sh
ps aux | grep test.sh | grep -v grep
Also as dirty workaround it is possible to copy and use bash with custom name:
sudo cp /usr/bin/bash /usr/bin/bash_with_other_name
/usr/bin/bash_with_other_name test.sh
ps aux | grep bash_with_other_name | grep -v grep
Erm... unless I'm misunderstanding the question, the name of a shell script is whatever you've named the file. If your script is named foo then killall foo will kill it.
We won't be able to find pid of the shell script using "ps -ef | grep {scriptName}" unless the name of script is overridden using shebang. Although all the running shell scripts come in response of "ps -ef | grep bash". But this will become trickier to identify the running process as there will be multiple bash processing running simultaneously.
So a better approach is to give an appropriate name to the shell script.
Edit the shell script file and use shebang (the very first line) to name the process e.g. #!/bin/bash /scriptName.sh
In this way we would be able to grep the process id of scriptName using
"ps -ef | grep {scriptName}"