Ps which is pid

The pgrep command looks at the processes currently running, and lists the process IDs that match the selection criteria. In my case it is Hence please exercise caution while looking at the results. The pstree command shows running processes as a tree-like format which is very convenient way to display the process hierarchy and makes the output more visually appealing. If a user name is specified in the pstree command then it shows all the processes owned by the respective user.

Output is unsorted by default. The PID of Apache2 is The ss command is used to dump socket statistics. It allows showing information similar to netstat. It can display more TCP and state information than other tools. The netstat command is used to print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. By default, netstat displays a list of open sockets.

Before we dive into the actual solution, let us briefly talk about how processes are created and identified by Linux. Every time a user or the system Linux launches a program, the kernel will create a process. A process holds execution details of the program in memory such as its input and output data, variables and so on. Importantly, since Linux is a multitasking operating system, it executes several programs simultaneously, and this means each process process must be identified specifically.

The kernel identifies each process using a process ID PID , a every instance of process must have a unique PID from other processes which is assigned when the process is invoked, to avoid any execution errors.

From the screenshot above, the numbered directories store information files about the processes in execution, where each number corresponds to a PID. You can monitor processes and their PIDs using traditional Linux commands such as ps , top and relatively new glances command plus many more as in the examples below:.

Monitor Linux processes using traditional top command. Monitor Linux processes using glances , a new real-time process monitoring tool for Linux. The second column in the output of ps specifies the terminal to which the process is attached or the terminal that controls the process. You can use the tty command to find out which terminal you are presently in.

Now, you may well expect that your machine has a lot more processes than the ones you see by running a simple ps without arguments. In fact, it shows only the processes you started from the terminal in which you issue the command. On a graphical desktop, that command doesn't show the programs you start from menus or by clicking on icons.

The system also runs a lot of its own processes in the background. To see everything, add the -e option:. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Ask Question. Asked 2 years, 11 months ago. Active 2 years, 11 months ago.

Viewed 7k times. According to man ps : -p pidlist Select by PID. This selects the processes whose process ID numbers appear in pidlist. Identical to p and --pid. With this option ps reads the necessary info only for the pids listed in the pidlist and doesn't apply additional filtering rules.

The order of pids is unsorted and preserved. No additional selection options, sorting and forest type listings are allowed in this mode.