Ubuntu Linux Toolbox: 1000+ Commands for Power Users, 2nd Edition

9

Checking and Managing Running Processes

IN THIS CHAPTER

Viewing active processes with ps and top

Searching for processes with pgrep

Adjusting CPU priority with nice and renice

Moving processes to the background or foreground

Killing and signaling processes with kill and killall

Using at and batch to run commands

Scheduling commands to run repeatedly with cron

When an executable program starts up, it runs as a process that is under the management of your Linux system's process table. Linux provides all the tools you need to view and change the processes running on your system.

The ps and top commands are great for viewing information on your running processes. There are literally dozens of options to ps and top to help you view process information exactly the way you want to. The pgrep command can further help find the process you want.

There are commands such as nice and renice for raising and lowering processor priority for a process. You can move processes to run in the background (bg command) or back to the foreground (fg command). On rare occasions, you can use the chrt command to run processes in realtime.

Sending signals to a process is a way of changing its behavior or killing it altogether. Using the kill and killall commands, you can send signals to processes by PID or name, respectively. You can also send other signals to processes to do such things as reread configuration files or continue with a stopped process.

To run commands at scheduled times or so they are ...