How to find the Process ID (PID) of a running terminal program?
I am running a program in the terminal that I can’t escape with Ctrl — C and that I want to kill. How can I find its PID?
This is a branch of What should I do when Ubuntu freezes? as a reference to prevent details in that question from becoming too technical.
11 Answers 11
Open another terminal and run ps ax | grep foo where foo is the name of the unresponsive program. This should return a line of output that looks something like this:
$ ps ax | grep firefox 2222 ? S 0:00 /bin/sh /usr/lib/firefox-3.6.9/firefox 2231 ? Sl 514:36 /usr/lib/firefox-3.6.9/firefox-bin 30290 pts/2 S+ 0:00 grep --color=auto firefox The first field of each line of output is a number which represents the Process ID of the program matched by grep (you can safely ignore the last one, which represents grep itself.
To halt the offending process, do: kill pid where pid is the Process ID of the program. You might have to use your judgment as to which of the matches needs to be kill ed, or you could use top instead. Using kill by itself sends SIGTERM, which you should try first as it allows the program to properly clean up after itself. If SIGTERM fails, try SIGHUP, which is stonger medicine: kill -HUP pid . If all else fails, send SIGKILL. But, you should only do so as a last resort, because SIGKILL causes the kernel to terminate the process immediately with no possibility for cleanup. This can at times result in data corruption or other problems. So again, only send SIGKILL as a last resort. To do so, do kill -KILL pid or kill -9 pid .
If you are running a graphical interface, of course, you don’t have to fool with this crazy command-line stuff to get the job done. Just open «System Monitor», navigate to the Processes tab, choose the process you want to halt (Hm, could it be the one using 90% CPU?) and right-click it. Since the process is already stopped, (that’s the problem, right?) choose End Process or Kill Process from the resulting menu.
How to Find a Process Name Using PID Number in Linux
In this article, we will look at how to find a process name by its process identification number (PID). Before we dive into the actual solution, let us briefly talk about how processes are created and identified by Linux.
Every time a user or the system (Linux) launches a program, the kernel will create a process. A process holds execution details of the program in memory such as its input and output data, variables and so on.
Importantly, since Linux is a multitasking operating system, it executes several programs simultaneously, and this means each process process must be identified specifically.
The kernel identifies each process using a process ID (PID), a every instance of process must have a unique PID from other processes which is assigned when the process is invoked, to avoid any execution errors.
The /proc file system stores information about currently running processes on your system, it contains directories for each process.
Use the ls command to list its contents, however, the list may be long, so employ a pipeline and the less utility to view the /proc contents in a more convenient way as below:
$ ls /proc OR $ ls /proc | less
1 168 2230 25 329 584 7386 83 driver schedstat 10 169 2234 2503 33 603 74 830 execdomains scsi 1070 17 2247 2507 34 610 7411 833 fb self 1081 1702 2256 2523 349 611 7423 836 filesystems slabinfo 109 1714 2258 253 35 612 745 839 fs softirqs 11 173 2266 2551 36 613 746 84 interrupts stat 110 1760 2273 26 362 62 75 844 iomem swaps 1188 1763 2278 2688 3642 63 7533 85 ioports sys 12 1769 2282 2694 3643 64 7589 86 irq sysrq-trigger 1204 177 2283 2695 37 6436 76 860 kallsyms sysvipc 1209 1773 2285 2698 38 65 7619 87 kcore thread-self 1254 18 2287 2699 39 66 7689 9 keys timer_list 13 1847 2295 27 3974 67 7690 94 key-users timer_stats 15 1914 23 2702 3976 68 77 977 kmsg tty 152 1917 2308 28 4273 6897 7725 981 kpagecgroup uptime 153 1918 2309 280 4374 69 7729 987 kpagecount version 154 1938 2310 2815 4392 6969 7733 997 kpageflags version_signature 155 1956 2311 2817 44 6980 78 acpi loadavg vmallocinfo 156 1981 2315 282 45 7 79 asound locks vmstat 1565 1986 2316 283 4543 70 790 buddyinfo mdstat zoneinfo 1567 1988 2317 29 46 71 8 bus meminfo 157 2 2324 2935 461 7102 80 cgroups misc 1579 20 2347 2944 4686 72 808 cmdline modules 158 2010 2354 3 47 73 81 consoles mounts 1584 2043 2436 30 4700 7304 810 cpuinfo mtrr 159 2044 2437 3016 5 7311 815 crypto net 1590 21 2442 31 515 7322 82 devices pagetypeinfo 16 2167 2443 318 5273 7347 820 diskstats partitions 160 22 2492 32 5274 7367 823 dma sched_debug
From the screenshot above, the numbered directories store information files about the processes in execution, where each number corresponds to a PID.
Below is the list of files for systemd process with PID 1:
ls: cannot read symbolic link '/proc/1/cwd': Permission denied ls: cannot read symbolic link '/proc/1/root': Permission denied ls: cannot read symbolic link '/proc/1/exe': Permission denied attr coredump_filter gid_map mountinfo oom_score schedstat status autogroup cpuset io mounts oom_score_adj sessionid syscall auxv cwd limits mountstats pagemap setgroups task cgroup environ loginuid net personality smaps timers clear_refs exe map_files ns projid_map stack uid_map cmdline fd maps numa_maps root stat wchan comm fdinfo mem oom_adj sched statm
You can monitor processes and their PIDs using traditional Linux commands such as ps, top and relatively new glances command plus many more as in the examples below:
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1 0.0 0.0 185728 6268 ? Ss 10:15 0:01 /sbin/init splash root 2 0.0 0.0 0 0 ? S 10:15 0:00 [kthreadd] root 3 0.0 0.0 0 0 ? S 10:15 0:00 [ksoftirqd/0] root 5 0.0 0.0 0 0 ? S< 10:15 0:00 [kworker/0:0H] root 7 0.0 0.0 0 0 ? S 10:15 0:09 [rcu_sched] root 8 0.0 0.0 0 0 ? S 10:15 0:00 [rcu_bh] root 9 0.0 0.0 0 0 ? S 10:15 0:00 [migration/0] root 10 0.0 0.0 0 0 ? S 10:15 0:00 [watchdog/0] root 11 0.0 0.0 0 0 ? S 10:15 0:00 [watchdog/1] root 12 0.0 0.0 0 0 ? S 10:15 0:00 [migration/1] root 13 0.0 0.0 0 0 ? S 10:15 0:00 [ksoftirqd/1] root 15 0.0 0.0 0 0 ? S< 10:15 0:00 [kworker/1:0H] root 16 0.0 0.0 0 0 ? S 10:15 0:00 [watchdog/2] root 17 0.0 0.0 0 0 ? S 10:15 0:00 [migration/2] root 18 0.0 0.0 0 0 ? S 10:15 0:00 [ksoftirqd/2] root 20 0.0 0.0 0 0 ? S< 10:15 0:00 [kworker/2:0H] root 21 0.0 0.0 0 0 ? S 10:15 0:00 [watchdog/3] root 22 0.0 0.0 0 0 ? S 10:15 0:00 [migration/3] root 23 0.0 0.0 0 0 ? S 10:15 0:00 [ksoftirqd/3] root 25 0.0 0.0 0 0 ? S< 10:15 0:00 [kworker/3:0H] root 26 0.0 0.0 0 0 ? S 10:15 0:00 [kdevtmpfs] root 27 0.0 0.0 0 0 ? S< 10:15 0:00 [netns] root 28 0.0 0.0 0 0 ? S< 10:15 0:00 [perf] .
Monitor Linux processes using traditional top command.
Monitor Linux processes using glances, a new real-time process monitoring tool for Linux.
Find Out Process PID Number
To find out the PID of a process, you can use pidof , a simple command to print out the PID of a process:
$ pidof firefox $ pidof python $ pidof cinnamon
Coming back to our point of focus, assuming you already know the PID of a process, you can print its name using the command form below:
Find Out Process Name Using PID Number
In this section, we will see how to find out a process name using its PID number with the help of user defined format i.e comm= which means command name, same as the process name.
$ ps -p 2523 -o comm= $ ps -p 2295 -o comm=
For additional usage information and options, look through the ps man page.
If you want to kill a process using its PID number, I suggest you to read Find and Kill Linux Processes Using its PID.
Thats it for the moment, if you know any other better way to find out a process name using PID, do share with us via our comment section below.
How to Find Process Name from its PID
If you know the PID of a process, here's how to get the process name in Linux command line.
If you know the process ID (PID), you can get the process name using the ps command:
The ps command is used for process related operations. In the above command, -p PID provides the process ID and -o comm= asks it to output the command associated with the given PID.
Honestly, it's difficult to remember the weird ps -p PID -o comm= syntax. And if that's the case, you may either look into the man page of ps command or use other ways of getting the details.
You can list all running process using the ps command or top command and note the process ID and process name as desired.
If you know the PID, you can simply use the grep command to filter the output and get the details on that PID:
But as illustrated by the image below, the output gives other details along with the process name.
That's not an issue if you are manually reading it. However, if you have to use it in a script, it could be an issue.
This is where the ps -p PID -o comm= is better.
Bonus tip: Since we are talking about process name and PIDs, let me quickly show you the reverse method, i.e., to find PID from process name.
There is a dedicated command called pidof and you can use it like this if you know the exact process name:
So, you just learned how to find process name from its PID in Linux command line and you also learned to get the PID from the process name.
If something isn't working right, or you just have any comments in general, feel free to leave any of it in the comments below.
Process name from its pid in linux
How to get a process name from his pid ? For example I execute cat file1.txt, but I want to figure out that cat command and its arguments since its pid in the system. Is there a struct to determine it or something similar? Any idea?
7 Answers 7
There is not any general way to do this unix.
Each OS has different ways to handle it and some are very hard. You mention Linux though. With Linux, the info is in the /proc filesystem.
To get the command line for process id 9999, read the file /proc/9999/cmdline .
The question was how to get the process name, not the commandline. On my SUSE I enter 'head /proc/9999/cmdline' for a kwrite process and it returns: 'kdeinit4: kwrite [kdeinit]'. If I use /comm instead of /cmdline I get the correct result: 'kwrite'.
@SkippyleGrandGourou /proc/
On linux, you can look in /proc/ . Try typing man proc for more information. The contents of /proc/$PID/cmdline will give you the command line that process $PID was run with. There is also /proc/self for examining yourself 🙂
An alternative (e.g. on Mac OS X) is to use libproc . See libproc.h.
POSIX C does NOT support give a standard API for getting the process name by PID.
In linux, you can get the name by LINUX Proc API: /proc/$PID/cmdline. And the code looks like these:
const char* get_process_name_by_pid(const int pid) < char* name = (char*)calloc(1024,sizeof(char)); if(name)< sprintf(name, "/proc/%d/cmdline",pid); FILE* f = fopen(name,"r"); if(f)< size_t size; size = fread(name, sizeof(char), 1024, f); if(size>0) < if('\n'==name[size-1]) name[size-1]='\0'; >fclose(f); > > return name; > And if you came here looking for a solution in C# working with mono, then have a look at this: stackoverflow.com/questions/29827331/…
To get the process name of a process id say 9000 use this command:
While this question has been answered, I'd like to add my 2 cents.
In my case, when process 1111 creates process 22222 via pipe (at least this is what I heard), /proc/2222/cmdline does not give correct process name, but instead gives something like 1111_1 . I have to use /proc/2222/comm to get the correct process name.
Use the below command in Linux
It will give the name of the process/application name