Graphical applications can refuse to respond to mouse clicks. When processes misbehave or malfunction, they can hog too much CPU time, consume your RAM, or enter a tight computational loop and become unresponsive. If the foreground processes are the front of theater staff and the actors, the background processes are the backstage 'behind the scenes' team. Background processes are things like services and daemons. They don't expect input from users nor do they present results or output to them.

Background processes are all of the processes that are started automatically and don't have any interaction with users.

They may be in a terminal window, or they may be a graphical application.

Foreground processes are ones that have been started or launched by a user.

Here, the refresh interval is set to 5 seconds using the sleep command.Running programs like your web browser, background processes associated with your desktop environment, and Linux system services are all processes.

if block: the -z option checks if a given string is empty, so we know whether any PIDs are returned and only use them as a filter when they are returnedīasically, the script keeps the output updated with data about the process with the given name.

_arg: stores the output (the list of processes) from the pgrep command.

pgrep: the -d option specifies a delimiter to use when printing the process IDs, while -f is used to match the full command line of a process instead of just the process name.

clear: clears the terminal screen for each iteration, similar to watch.

while loop: runs the process list iteration indefinitely until the script is interrupted.

_process_name: name of the variable which sets the name of the process from the first command line argument ( $1).

Let’s break down this script and see the meaning of the various commands used here: For example, let’s consider the script ( my_script.sh) below: #!/bin/bash To resolve this problem, we can use a script to filter the results of the top command by process name. Consequently, the top command needs to restart to retrieve the full list of target process PIDs.

However, when we restart a process, its PID changes. $ top -c -p $(pgrep -d',' -f matching_string_in_cmdline_output) Notably, there can be several processes with the same name, but different PIDs. Tasks: 110 total, 1 running, 109 sleeping, 0 stopped, 0 zombie Īdd filter #1 (ignoring case) as: FLD?VAL COMMAND=apache2įinally, the top command should now only display the statistics of the apache2 process : top - 03:46:28 up 9 min, 1 user, load average: 0.00, 0.08, 0.08 Hence, we join these strings with an equals sign, so our filter to single out apache2 becomes COMMAND=apache2.

In our case, the field is COMMAND, while the value should be apache2. Now, let’s press the O key, which brings up a prompt asking us to enter the field and value to filter.

Linux list all processes and name