Monitoring processes using ps_Learning Linux Shell Scripting-QQ阅读男频武侠网

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Monitoring processes using ps

We have used the command ps in the introduction. Let's learn more about it:

To list the process associated with our current Bash shell terminal, enter the following command:
```
$ ps
```
To list processes along with the parent process ID associated with the current terminal, enter the following command:
```
$ ps –f
```
We can see the process ID in the PID column and the parent process ID in the PPID column in the preceding output.
To list processes with the parent process ID along with the process state, enter the following command:
```
$ ps –lf
```
In the preceding output, the column with S (state) shows the current state of a process, such as R for running and S for suspended state.
To list all the processes running in the operating system including system processes, enter the following command:
```
$ ps –ef
```
The process names in [] are kernel threads. If you are interested in more options to learn about the ps command, you can use the following command:
```
$ man ps.
```
To find a particular process, you can use the following command:
```
$ ps –ef | grep "process_name"
```
The command with grep will display the process with process_name.
If we want to terminate the running process, enter following command:
```
$ kill pid_of_process_to_be_killed
```
Many a time, if the process is not killed by the $ kill command, you may need to pass additional option to ensure that the required process is killed, which is shown as follows:
```
$ kill -9 pid_of_process_to_be_killed
```
We can terminate the process by the name of a process instead of using the process ID as follows:
```
$ pkill command_name
$ pkill sleep
```
Or:
```
$ pkill -9 command_name
```
To know more about various flags of kill, enter following command:
```
$ kill –l
```
This displays all the signals or software interrupts used by the operating system. When we enter the $ kill command, the operating system sends the SIGTERM signal to the process. If the process is not killed by this command, then we enter the following command:
```
$ kill -9 process_name
```
This sends SIGKILL to the process to be killed.