The ps (process status) command is used to provide information about the currently running processes, including their process identification numbers (PIDs), USER, TTY, %CPU, %MEM and command. Every process is assigned a unique ID the system that is called PID. Here USER is the username, under which a process is running.
The %CPU shows percentage (%) of cpu usage of process and %MEM shows percentage (%) of memory usage of each running process in the system.
PS command usage
A common and convenient way of using ps command to obtain complete information about the processes currently on the system as follows:
$ ps -aufx
Here -a option tells ps to list the processes of all users on the system rather than just those of the current user, -u and -f options tell ps to provide detailed and full information about each process. The -x option adds to the list processes that have no controlling terminal, such as daemon.
In this tutorial I will discuss how to use ps command in Linux to check memory the process usage.
Check the memory usage for all processes
The following ps command will display %MEM in 1st column, PID in 2nd column and command in 3rd column for all running processes on the system:
$ ps -eo pmem,pid,cmd | sort -k 1 -nr
Output 3.9 3094 /usr/sbin/mysqld 2.1 1779 iscsiuio 2.0 5371 /home/btest/TopCMM/ 1.4 15386 /usr/bin/php 1.0 14465 /usr/local/apache/bin/httpd -DSSL 0.8 14515 /usr/local/apache/bin/httpd -DSSL 0.7 14514 /usr/local/apache/bin/httpd -DSSL 0.7 14511 /usr/local/apache/bin/httpd -DSSL 0.3 31925 lfd - sleeping 0.3 15377 /usr/sbin/exim -bd -q60m 0.2 9527 tailwatchd 0.2 5577 /usr/bin/python -tt /usr/sbin/yum-updatesd 0.2 2934 /usr/sbin/named -u named
Top 5 processes by memory usage
To display top 5 processes by memory usage enter the following ps command from the terminal:
$ ps -eo pmem,pid,cmd | sort -k 1 -nr | head -5
Output 3.5 3094 /usr/sbin/mysqld 2.1 1779 iscsiuio 2.0 5371 /home/btest/TopCMM/ 1.4 15386 /usr/bin/php 1.0 14465 /usr/local/apache/bin/httpd -DSSL
Conclusion
In this short tutorial we learn two ps command to check memory usage of a running process in a Linux system. If you have any questions or feedback, feel free to leave a comment.
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