Given a pid, for example 29264， how to get to know whether the process is running ?
Is there any easy way to do that ?
thx
Process status (ps) provides the information you're looking for:
ps -p 29264
Output in case the process is running (quick example on my Mac, works the same on Linux):
PID TIME CMD
127 4:54.03 /System/Library/CoreServices/Finder.app/Contents/MacOS/Finder
Otherwhise:
PID TIME CMD
kill -0 29264 ,and inspect the error (if any)
link to online linux (man 2) manual
link to online linux (man 1) manual
To get process status:
ps -p 29264 > /dev/null; echo $?
Related
I ran an ssh command doing the following: ssh user#remote "my command &". Now the process seems to be running in the background, but I cannot find it, and I want to end it. I've used netstat, but cannot find the process.
Didn't you expect it to run in the background? Thats what the & does. You can use ps af to show all of the processes running under your username. You can then kill it by PID.
Thanks everybody. I found the process doing ps aux. For some reason, the port that it was using wasn't being display in netstat.
I suggest some methods
sudo killall ssh
It may not be the best method to use this method, it is better to filter first and then close it
or
ps -o pid,cmd | grep ssh
kill -QUIT (pid)
To stop a program, send the QUIT signal.
I'm running the following command in Linux:
sudo ./tftpCommand &
where my executable tftpCommand file simply gets/puts a data file which sometimes does not exist.
I want to be able to stop the tftp command that was spawned in the subshell before it automatically times out.
Using something like kill $(jobs -p) shows that the subshell has been terminated but the tftp still runs -- I know this because several seconds later it prints to the shell that it can't find the file to transfer.
QUESTION: How do I ensure that the tftp command is killed alongside the subshell that runs it?
Thanks!
I've found a solution to my problem:
use pkill -c tftp to kill any current tftp commands.
I figured this out by using ps x -o "%p %r %c"
You can use a similar technique for any of the command names in the COMMAND column (corresponding to the %c and -c ) to kill other processes.
Hope that helps anyone else who stumbles upon the same problem!
I've googled this question, but never found anything useful for my particular case.
So, what I'm trying to figure out is the PID of a certain command that is running so I can kill it if necessary. I know it's possible to get the PID of a command by typing echo $! So supposedly
my_command & echo $!
should give me the PID. But this isn't the case, and I think I know why:
My command is as follows:
screen -d -m -S Radio /path/to/folder -f frequency -r path/to/song
which opens a detached screen first and then types the command so that it gets executed and keeps on running in the background. This way the PID that echo shows me is the wrong one. I'm guessing it shows me PID of screen -d -m -S Radio /path/to/folder -f frequency -r path/to/song instead of the PID of the command run in the new terminal created by screen.
But there's another problem to it: when I run screen -ls in the terminal, the command that is running in the background doesn't show up! I'm fairly certain it's running because the Pi is constantly at 25% CPU usage (instead of the 0% or 1% usually) and when I type ps au I can actually see the command and the PID.
So now I'm calling the community: any idea on how I could find the PID of that certain command in the new terminal? I'm writing a bash script, so it has to be possible to obtain the PID through code. Perfect would be a command that stores the PID in a variable!
Thanks to #glennjackman I managed to get the PID I wanted with a simple pgrep search_word. At first it wasn't working, but somehow I made it work after some trial and error. For those wanting the PID on a variable, just type
pid=$(pgrep search_word)
Regarding the problem with screen -ls not showing my detached session, it's still not solved, but I'm not bothered with it. Thanks again for solving my problem #glennjackman !
EDIT:
Second problem solved, check the comments on berends answer.
You can easily find out all the running process and their PID by writing (for example):
ps aux
The process is run by screen so you can probably find it easier by writing:
ps aux | grep screen
For more info about ps and the parameters I used check (quick google) -> https://www.lifewire.com/g00/uses-of-linux-ps-command-4058715?i10c
EDIT: You can use this command with bash scripting as well.
I want to monitor all the running processes using strace and when a process ends the output of the strace should be sent to a file.
And how to find every running proc PID. I also want to include process name in the output file.
$ sudo strace -p 1725 -o firefox_trace.txt
$ tail -f firefox_trace.txt
1725 would be the PID of the proccess you want to monitor (you can find the PID with "ps -C firefox-bin", for firefox in the example)
And firefox_trace.txt would be the output file !
The way to got would be to find every running proc PID, and use the command to write them in the output file !
Considering the doc,
-p pid
Attach to the process with the process ID pid and begin tracing. The
trace may be terminated at any time by a keyboard interrupt signal (
CTRL -C). strace will respond by detaching itself from the traced
process(es) leaving it (them) to continue running. Multiple -p options
can be used to attach to up to 32 processes in addition to command
(which is optional if at least one -p option is given).
Use -o to store the output to the file, or 2>&1 to redirect standard error to output, so you can filter it (grep) or redirect it into file (> file).
To monitor process without knowing its PID, but name, you can use pgrep command, e.g.
strace -p $(pgrep command) -o file.out
where command is your name of process (e.g. php, Chrome, etc.).
To learn more about parameters, check man strace.
How do I get the pid of a process as soon as it opens. Like lets say we run ./file.pl and then ./file2.pl As both these files will create a pid in /proc/ folder. How do I instantly know if the process has been created when the executable is run.
I have a file with all the commands ready to be run as soon as it gets the green signal that there is a new process in the /proc/ folder. How do I do that?
EDIT:
Please don't answer with a shell command. I don't need to know the pid. I need to develop a script which can know right away that we have a guest in the proc department
If you start the process via a shell, then start process in background:
./your_prog &
Get the pid:
echo $!
If the script give you the shell prompt back, you can do :
./your_prog
pidof -x your_prog
Tested OK with this perl script :
#!/usr/bin/perl
if (fork() == 0) {
sleep(600);
}
you need to
chmod +x your_prog
before...
Every process can get its own pid with the getpid(2) syscall. At process creation by fork(2) the parent process (e.g. some shell) gets the pid of the new child process. Read e.g. Advanced Linux Programming for more. And the kernel (not the program) is creating some subdirectory /proc/1234/ see proc(5) as soon as it creates the process of pid 1234.
Actually, /proc/ is not a real file system. It is just a pseudo file system giving a view on the state of the kernel and the entire Linux system.
Perl gives you its POSIX module to interface the syscalls. The getpid() syscall is interfaced using the $PID or $$ Perl variable.
The /proc/ pseudo filesystem is filled by the kernel. You could perhaps use inotify to follow change in /proc/ but this is very probably a bad idea.
Your question is not clear, we cannot understand what you really want to do and what you have tried.
Try out below shell script.(You may have to include changes in below script for your expected output)
#!/bin/bash
nr_proc_before=`ls -l /proc | wc -l`
ls /proc > proc_list_before
./any_executable &
nr_proc_after=`ls -l /proc | wc -l`
ls /proc > proc_list_after
nr_new=`expr $nr_proc_after - $nr_proc_before`
echo "$nr_new processes are created newly"
echo "new processes pids are :"
diff proc_list_after proc_list_before > new_pids
sed "1d" new_pids
if [ nr_new > 0 ] ; then
#trigger your file which has commands.
fi
Insted of any_execuatble you can replace with your things so that new processes will be created.
Note : This is not a script which monitors for new process. This sample of script may give you idea to solve your problem.
Please do reply for this answer, i can redefine my answer.