1.6 Process and job control commands
Simply put, a process is the process of executing a program or task. In a Linux system, executing any command creates one or more processes. That is, the command is implemented through a process.
The multitasking concept of Linux operating systems can be better understood from a process perspective. For http://www.aliyun.com/zixun/aggregation/13879.html "> system administrators, the management system process is an important part of day-to-day management."
Viewing process status in the system with PS
You can see the status of the process through the PS command, which will show the state of the current instantaneous process. Depending on the information displayed, determine which process is running, which process is suspended, or how long the process has been running, the resources the process is using, the relative priority of the process, and the process's identification number (PID). This information is useful to users, and for system administrators
More important. The general usage of the PS command is:
ps [option] [arguments] ...
The PS command has the following key parameters:
-A: Displays the status of all user processes including the system-F: Displaying the tree directory of processes and subprocess-L: Displaying process information as a long list-only running Processes-U: Displays process information in user format, gives user name and start time PIDs: Displays process information for the specified ID
Without any options, the PS command lists the PID for each process associated with your current shell. The results are as follows:
PID TTY Time CMD
596 pts/0 Unlimited Bash
627 Pts/0 Unlimited VI
628 Pts/0 Unlimited PS
Where the meanings of each field are as follows:
PID: Process identification number
TTY: Start the process's terminal number
Time: reports the cumulative CPU times used by the process
CMD: Executing process name
To obtain a complete list of process information, you can use the PS command with the following options:
Ps–aux
In addition to listing the above fields, it also lists CPU usage (%CPU), Memory usage (%MEM), virtual image size, host DataSet size (RSS), terminal number (TTY), status (STAT), and so on.