What is PS command
See its man page can be seen, ps command can give a snapshot of the current processes in the system. It can capture process status of an event in the system. If you want to view the status of constantly updated, you can use the top command.
ps command supports syntax used in three of
UNIX-style options can be combined and the former option must have "-" hyphen
BSD-style options can be combined, but not before there are options "-" hyphen
long options GNU style, there are two options before. " - "hyphen
We can mix these types of style, but may conflict. As used herein, UNIX-style ps command. Here is an example using more ps command in everyday life.
1. ps command with no arguments
This is a basic ps use. Execute this command in the console and see the results.
The results will show four default information.
PID: command (CMD) of the running process ID
TTY: position command is running (terminal)
the TIME: the CPU processing time running the command occupied
CMD: The command process running
This information is not sorted when displayed.
2. Display all the current process
Use -a parameter. -a representative of all. At the same time plus x parameter will be displayed without the controlling terminal.
The results of this command may be very long. For ease of viewing, and the pipe may be combined to use less command.
In the case of the need for specific user processes, we can use the -u parameter. For example, we want to see users 'kseven' process, you can use the following command:
4. The filtering process through the use of memory and cpu
Maybe you want to put the results in accordance with the CPU or memory usage to screen, so you find what process is using your resources. To do this, we can use the aux parameter to display comprehensive information:
When the result is very long, we can use the less command to filter and pipes.
The default result set is not sorted. You can sort by --sort command.
The CPU using an ascending sort
The memory using an ascending sort
We can also combine them into one command and displays the first 10 results through the pipeline:
5. filtered through the process name and PID
Use the -C parameter, followed by the name of the process that you are looking for. For example, you want to display a message called getty process, you can use the following command:
If you want to see more detail, we can use the -f option to view a list of formatted information:
6. The process according to filter thread
If we want to know the thread-specific process, you can use -L parameter, followed by the specific PID.
7. The tree display process
Sometimes we want to show the process tree structure, you can use -axjf parameters.
Or you can use another command.
8. Display Security Information
If you want to see now who logged into your server. You can use the ps command with the parameters:
-E parameter displays all process information, -o parameter control output. Pid, User and Args parameter display PID, the user running the application and the application.
Keywords can be used with the -e parameter is args, cmd, comm, command, fname, ucmd, ucomm, lstart, bsdstart and start.
9. The process of formatting the output root user (real or effective UID) is created
When the system administrator wants to see the process run by the root user and other information about this process, you can use the following command:
-U parameter screening process by the real user ID (RUID), it will choose the real user name or ID from the user list. That is the real user of the process of actually creating the user.
-u parameter is used to screen for effective user ID (EUID).
U parameter is used to determine the final format for output to the user by the User, PID,% CPU,% MEM, VSZ, RSS, TTY, STAT, START, TIME and COMMAND these columns.
Here are the above command output:
10 PS using real-time monitoring process status
ps command will show the current state of your system process, but the result is static.
When there is a situation, we need to be screened by the CPU and memory usage process as mentioned above, the fourth point, and we hope that the results can be refreshed once per second. To this end, we can watch the ps command and the command together.
If the output is too long, we can limit it, such as before 20, we can use the head command to do.
The view here is not as dynamic top or htop command. But the benefits of using ps is a field that you can customize the display, you can select the fields you want to view.
For example, if you only need to look at information about the user named 'pungki', you can use the following command: