I want to look for a specific process and then kill it (in a script).
I'm doing ps -fu user | grep matching_string but this is returning me two rows: one for the expected pid and another for the pid of the grep.
If the result were two columns, I would use awk to pick the first one. But I don't know how to pick the first result when they are returned as row.
How about pkill?
pkill -U user-id process-name
You can use this trick:
ps -fu user | grep matching_strin[g]
This way, the grep match won't appear.
How does it work? (see Find and kill a process in one line using bash and regex for more detail).
With ps -fu user | grep matching_string it lists all the processes having grep matching_string, so that includes the grep itself.
Doing ps -fu user | grep matching_strin[g] you add a regular expression that makes grep skip the grep itself. Why? Because the process name is grep matching_strin[g] and does not match the literal matching_string.
Related
I have written one shell script which kills a process based on certain condition.
My script 'A' will call another script 'B' which identifies process id and kill it.
Before running the script I have ran
ps -ef | grep processA
This gave me result process id, say, 11111
The script B gets process id through this command
ps -ef|grep processA|grep -v stop|grep -v grep|awk ' { print $2 } '
I have added the same command in script A and got process id as 11111
However when it gets invoked in script B, the process id will be different, say, 22222.
I am not sure why even though it is same command, the process id identified are different. Is there any explanation for this?
First of all, are you sure that it's the same command in script A as in Script B?
Second, if you are interested in the PID of processA you can do
pgrep processA
which will give you the PID of processA directly.
Third, what are you trying to achieve with the command
ps -ef | grep processA | grep -v stop | grep -v grep | awk '{ print $2 }'
It looks like you are looking for the processA, but you only want the processes without containing the word 'stop' and 'grep'. Using pgrep, you will not get the grep process looking for processA.
If you provide more information (e.g. your scripts), we can help you better.
Get the process id and kill it? Here is one other way:
> proc_name=$1".pid"
> pid=$(cat /var/run/$proc_name)
> kill -9 $pid
I stumbled upon a shell instruction which looks odd:
ls -a | grep ".qmail-" | grep -v "mail" | grep ".mail" > t ; echo $?
I suspect that the returned value would represent an error. Could anyone confirm this or explain in which circumstances this instruction would be applied ?
The first grep only allows through lines that contain qmail (preceded by any character and followed by a dash, but that is largely immaterial). The second grep strips out lines that contain mail, which means every line passed by the first grep is deleted by the second. There's nothing left for the third one to process, so the file t will always be empty. The value for $? should be 1, failure, since the third grep failed to find any lines that matched its pattern (because it got no lines to process).
It is a mistake.
It is hard to know how to fix it without knowing what it is trying to do.
The bash shell (and most other shells) let users use the output of one command as the input of another. This is accomplished with the | operator which is called a pipe. So the output of of ls -a is fed to grep ".qmail-" and so on. The > operator sends the output of the command to a file, in this case t. So ls -a | grep ".qmail-" | grep -v "mail" | grep ".mail" > t lists the contents of a directory and passes the output through successive filters before finally saving the output to the file t.
The semicolon signals the end of a command and allows multiple bash commands to be entered on a single line.
echo $? prints out the return value of the last executed command, in this case, ls -a | grep ".qmail-" | grep -v "mail" | grep ".mail" > t. By convention, any value besides 0 indicates some sort of error occurred.The Linux Documentation Project gives a list of some common exit codes.
I am trying to execute a couple of complicated grep commands via a shells script that work fin in the terminal manually executed. I can't for the life of me figure out why this doesn't work.
The goal of the first grep is to get out any process id attached to the parent myPattern. The 2nd get the process id of the process myPattern
Currently my shell script
returns nothing for the 1st.
ignores the "grep -v 'grep'" part in the 2nd.
#!/bin/sh
ps -ef | grep "$(ps -ef | grep 'myPattern' | grep -v grep | awk '{print $2}')" | grep -v grep | grep -v myPattern | awk '{print $2}'
ps -ef | grep 'myPattern' | grep -v 'grep' | awk '{print $2}'
This works fine when run in the terminal manually. Any ideas where i have stuffed this up?
Your first command is vague. I don't think it would reliably do what you describe. It also does not guard against getting the id of the first grep call. The second one works for me. For the fists query it highly depends on the system you are using. It's easier to use pstree to show you the whole process tree under a pid. Like:
pstree -p 1782 | sed 's/-/\n/g' | sed -n -e 's/.*(\([0-9]\+\)).*/\1/p'
You need to limit pid to be a single value. If you have more values, then you have to loop through them. If you don't have pstree, then you can craft some loop around ps. Make note that even if you current commands worked, then thwy would catch only one level parent/child relationships. pstree does any level.
I also have to tell you that a process can escape original parent as a parent process by forking.
In any case without exact details what you are trying to achieve and why, and on what platform it is hard to give you a great answer. Also these utilities albeit present virtually everywhere are not as portable as one would wish.
One more note - /bin/sh is often not your current shell. On many linux systems user has a default shell of bash and /bin/sh is dash or some other shell variant. So if you see diffs with what you have in console and script, it can be difference in actual shell you are using.
Based on user feedback it would be much easier to have something like this in the java process launching script:
java <your params here> &
echo $! > /var/run/myprog.pid
Then the kill script would look like echo /var/run/myprog.pid | xargs kill. There are shorter commands but I think this is more portable. Give actual code if you want more specific.
I am writing a script to monitor the CPU and MEM of any given process. For that i need to send in the name of the process to be monitored as a commandline argument. For example.
./monitorscript <pname>
I need to get the pid of the process in the script so that i can use a ps -p <pid> inside.
How do i get the pid of a process given its process name?
I understand that there might be multiple processes in the same name. I just want to get the first process out of that list.
The answer above was mostly correct, just needed some tweaking for the different parameters in Mac OSX.
ps -A | grep [f]irefox | awk '{print $1}'
You can use the pgrep command like in the following example
$ pgrep Keychain\ Access
44186
You can install pidof with Homebrew:
brew install pidof
pidof <process_name>
This solution matches the process name more strictly:
ps -Ac -o pid,comm | awk '/^ *[0-9]+ Dropbox$/ {print $1}'
This solution has the following advantages:
it ignores command line arguments like tail -f ~/Dropbox
it ignores processes inside a directory like ~/Dropbox/foo.sh
it ignores processes with names like ~/DropboxUID.sh
This is the shortest command I could find that does the job:
ps -ax | awk '/[t]he_app_name/{print $1}'
Putting brackets around the first letter stops awk from finding the awk process itself.
Try this one:
echo "$(ps -ceo pid=,comm= | awk '/firefox/ { print $1; exit }')"
The ps command produces output like this, with the PID in the first column and the executable name (only) in the second column:
bookworm% ps -ceo pid=,comm=
1 launchd
10 kextd
11 UserEventAgent
12 mDNSResponder
13 opendirectoryd
14 notifyd
15 configd
...which awk processes, printing the first column (pid) and exiting after the first match.
You can try this
pid=$(ps -o pid=,comm= | grep -m1 $procname | cut -d' ' -f1)
ps -o ppid=$(ps -ax | grep nameOfProcess | awk '{print $1}')
Prints out the changing process pid and then the parent PID. You can then kill the parent, or you can use that parentPID in the following command to get the name of the parent process:
ps -p parentPID -o comm=
For me the parent was 'login' :\
Why don't you run TOP and use the options to sort by other metrics, other than PID? Like, highest used PID from the CPU/MEM?
top -o cpu <---sorts all processes by CPU Usage
In a shell script lets say i have run a command like this
for i in `ps -ax|grep "myproj"`
do
echo $i
done
Here, the grep command would be executed as a separate process. Then how do i get its PID in the shell script ?
I'm going out on a limb here, and understand this looks more like a comment.
Why do you need the PID of the grep command?
In your comment you say you want to compare it in the loop against something. I would suppose that it is your issue that that the loop will (sometimes) not only include myproj but also an item about your grep command? If so, try the following:
for i in `ps -ax | grep -v grep | grep "myproj"`
do
echo $i
done
The -v switch basically inverts the pattern, so grep -v grep (or grep -v "grep", which maybe looks a bit less awkward) will include only lines that do not include the string "grep" (see man grep).
Note that this maybe overly vague for some cases, for example if the pattern you actually look for also contains the string "grep". For example, the following might not work as you'd expect: ps -ax | grep -v grep | grep mygrepling
However, in your particular case, where you only look for "myproj" it will do.
Or you could simply use
for i in `ps -ax | grep "my[p]roj"`
do
echo $i
done
That way there is no need to know the PID of the grep command, because it simply never shows up as a loop iteration.
When you run a process in background, you can get its PID in $!
$ ps aux | grep dddddd & echo $!
[1] 27948
27948
ic 27948 0.0 0.0 3932 760 pts/3 R 08:49 0:00 grep dddddd
When in foreground --- the process does not exist anymore at the point you want to find its PID. When you are in the loop, the for statement is already executed and grep is already exited, so you can not find its PID anymore.