How to use the command killall (with examples)
The command killall is used to send a kill signal to all instances of a process by name. It allows users to terminate processes using different signals and provides options for confirmation and forceful termination. This article will provide examples of different use cases of the killall command.
Use case 1: Terminate a process using the default SIGTERM signal
Code:
killall process_name
Motivation:
Sometimes, a process may become unresponsive or need to be terminated gracefully. Using the killall command with the process name allows users to terminate all instances of the process at once.
Explanation:
The command killall is followed by the name of the process that needs to be terminated. By default, the SIGTERM signal is used, which instructs the process to terminate gracefully.
Example output:
[1]+ Terminated process_name
[2]+ Terminated process_name
...
Use case 2: List available signal names
Code:
killall -l
Motivation: To terminate a process using a specific signal, it is important to know the available signal names. This command allows users to easily list all available signal names without the “SIG” prefix.
Explanation:
The -l flag is used with the killall command to list all available signal names. This information can be helpful when selecting a signal for terminating a process.
Example output:
HUP INT QUIT ILL ...
Use case 3: Interactively ask for confirmation before termination
Code:
killall -i process_name
Motivation:
Sometimes, it is important to confirm before terminating a process to prevent accidental termination. The -i option prompts the user for confirmation for each process instance.
Explanation:
The -i flag is used with the killall command to interactively ask for confirmation before terminating each process instance. The user will be prompted with a confirmation message for each instance of the process.
Example output:
Kill process_name (y/N)?
Use case 4: Terminate a process using the SIGINT signal
Code:
killall -INT process_name
Motivation:
Using the SIGINT signal to terminate a process is the same as pressing Ctrl + C. This use case is helpful when trying to terminate a process gracefully.
Explanation:
The -INT option is used with the killall command to send the SIGINT signal, which is the interrupt signal. This signal is commonly used to terminate a process gracefully and is the same as pressing Ctrl + C in the terminal.
Example output:
[1]+ Interrupt process_name
[2]+ Interrupt process_name
...
Use case 5: Force kill a process
Code:
killall -KILL process_name
Motivation:
In some cases, a process may not respond to the default termination signals. The -KILL option forcefully terminates the process by sending the SIGKILL signal.
Explanation:
The -KILL option is used with the killall command to send the SIGKILL signal, which is a non-interceptable signal that forces the process to terminate immediately. This should be used as a last resort if other termination signals don’t work.
Example output:
[1]+ Killed process_name
[2]+ Killed process_name
...
Conclusion:
In this article, we have explored various use cases of the killall command. From terminating processes gracefully to forcefully terminating unresponsive processes, the killall command provides flexibility and control over process termination. With the examples provided, users can easily utilize the command according to their specific requirements.
