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Linux Killall Command: Kill A Specific Group Of Processes

The killall command in Linux is a useful tool for terminating running processes based on their names. This command sends a signal to all instances of a specified process, allowing you to stop or restart multiple processes simultaneously. In this tutorial, we'll cover basic usage examples for the killall command.

Terminate a process by name:

To terminate all instances of a process by its name, use the killall command followed by the process name:

killall process_name

For example, to terminate all instances of the gedit text editor, run:

killall gedit

By default, killall sends the SIGTERM signal, which allows processes to perform cleanup operations before exiting gracefully.

Send a specific signal:

To send a specific signal to processes, use the -s option followed by the signal name or number:

killall -s signal_name process_name

For example, to send the SIGHUP signal to all nginx processes, run:

killall -s SIGHUP nginx

Terminate processes older or younger than a certain time:

To terminate processes older or younger than a certain time, use the -o (older) or -y (younger) options followed by the time:

killall -o time process_name
killall -y time process_name

The time should be in the format dd[-]hh:mm:ss. For example, to terminate all gedit processes older than 1 hour, run:

killall -o 1:00:00 gedit

Display a list of killed processes:

To display a list of killed processes, use the -v (verbose) option:

killall -v process_name

This command will show which processes have been terminated by the killall command.

Ignore case when matching process names:

To ignore case when matching process names, use the -I (ignore case) option:

killall -I process_name

For example, to terminate all instances of the gedit text editor regardless of case, run:

killall -I GEDIT

In summary, the killall command allows you to efficiently manage and terminate processes in Linux by sending signals based on process names. By using various options, you can send specific signals, target processes based on age, display a list of killed processes, and more.

How to use the killall command in Linux:
The killall command is used to send signals to processes by name, allowing you to terminate or signal multiple processes simultaneously.
Example code:
```
killall process_name
```
Killing a group of processes with killall:
You can use killall to terminate all processes in a specific process group.
Example code:
```
killall -g process_group_name
```
Terminating processes by name using killall:
killall can terminate processes by specifying their name.
Example code:
```
killall process_name
```
Killing processes based on process group with killall:
Processes can be terminated based on their process group using the -g option.
Example code:
```
killall -g process_group_name
```
Forcefully terminating processes with killall in Linux:
To forcefully terminate processes, you can use the -9 option, which sends the SIGKILL signal.
Example code:
```
killall -9 process_name
```
Using signal options with killall command:
You can specify a signal to send to processes using the -s option.
Example code:
```
killall -s SIGNAL process_name
```
Viewing and selecting processes for termination with killall:
Before actually terminating processes, you can use the -i option to interactively select processes.
Example code:
```
killall -i process_name
```
Recursive killing of processes with killall in Linux:
The -r option allows killall to search and kill processes recursively.
Example code:
```
killall -r process_name
```
Troubleshooting issues with killall command:
Common issues may include incorrect process names or insufficient permissions. Ensure correct process names and use appropriate permissions.
Example code (checking permissions):
```
ls -l $(which killall)
```