How to know the process PID in linux machine

Question

I am launching an installer from java to install a software on linux, I want to to know the "process id and image name" of it.

In windows I able to get it by using tasklist command, but in linux I have not been able to do the same. I tried with ps -ef and ps -A commands, but its not showing the image name or PID of process.

Is there any command to get it these values?

Answer 1

Most modern Linux distros have handy command pgrep (process grep), which was created just for this purpose. Use it like this:

pgrep -lf programname

Unlike naive ps ax | grep programname, pgrep knows how to not display process id of itself.

There is also complementary utility pkill, which can kill process by name (or send other signals).

Answer 2

if it is a graphical installer you can run this one-liner in a terminal:

ps -fp $(xprop _NET_WM_PID | cut -d' ' -f3)

your mouse cursor will change to a crosshair. Now click on the window in question. you should now see process information printed in the terminal.

Answer 3

Try ps -aef | grep your_process_name, replace your_process_name with your installer name.

Hope this helps !!

Answer 4

It is generally best to capture the process ID at the time you launch it rather than trying to find it later on.

If using the C API, you get the PID of the spawned process as the return value from fork or vfork in the mother process.

In a Bourne derived shell you use $! immediately after starting it.

Answer 5

It seems that your are looking for a Linux centric solution rather than a portable one. On Linux the easy, efficient and reliable way to get the information you need from Java is to use the proc filesystem, and especially the /proc/self directory. The man 5 proc manpage describe each file.

The pid is first field of /proc/self/stat. The image name is the second one.

It is very easy to write a class to wrap these calls. It will be only a few lines of code doing basic IO: fast and robust. Using third party programs is harder to get right and less efficient.

This solution is not portable since most of the Unix systems do not have a proc filesystem. You have four options from the best to the worst, IMHO:

• Capture the information you need before starting the process: Could be easy or not depending of your application
• Find clean & system specific implementations like the proc file system for Linux
• Use unspecified API. RuntimeMXBean.getName() usually returns the pid, you can also use reflection to get access to java.lang.UnixProcess.pid. Implementation can differs between JVM and can change at any time. Acceptable solutions if you control the environment.
• Write native code to access the POSIX API
• Use external tools like ps

If you decide to rely on external tools then you should be very careful about portability (options and output can differs greatly between two OS) and locale settings.