Linux has a subtle yet powerful command line interface that empowers its users with a broad range of functionalities. But what happens when you want to cancel a command that you’ve issued? Whether you’ve started a process that’s taking longer than expected or you’ve made a mistake, Linux comes with built-in commands that allow you to cancel the ongoing operation swiftly and gracefully. In this blog post, we’ll guide you through the process of how to cancel a command in Linux.
Using Control Commands
The most common way to cancel a command in Linux is by using control commands. The two primarily used control commands are Ctrl+C and Ctrl+Z.
1. Ctrl+C
This command is used to send a SIGINT (Signal Interrupt) to the process. It is typically used to terminate the process that is currently in progress in the terminal.
For instance, if you have started a process, you can simply press Ctrl+C to stop it. Here’s how it will look:
$ long_running_command ^C $
After hitting Ctrl+C, the process will be immediately stopped and you’ll get your command prompt back.
2. Ctrl+Z
This command is used to send a SIGSTOP or Signal Stop to the running process. Unlike SIGINT, this doesn’t terminate the process—instead, it puts the process into the background and suspends its execution. This allows you to resume the process later on.
For instance, if you need to pause the process, you can simply press Ctrl+Z. Here’s how it will work:
$ long_running_command ^Z [1]+ Stopped long_running_command $
After hitting Ctrl+Z, the process is suspended and moved to the background. You can resume it later by using the fg command.
Using kill Command
In some cases, if Ctrl+C and Ctrl+Z don’t work, you might need to use the kill command to cancel a process. However, this requires knowing the process ID (PID). You can find the PID by using the ps command or the pgrep command.
Here’s how you can find the PID and then use the kill command to cancel the process:
$ ps aux | grep long_running_command $ kill -9 PID
Replace PID with the actual process ID. The -9 option sends the SIGKILL signal, which immediately terminates the process.
These are some of the primary ways to cancel a command in Linux. Always exercise caution when cancelling processes, especially when using the kill command, as improper use can cause system instability.
Conclusion
Working with Linux command line interface involves running various commands and sometimes, you may need to cancel a few. With the above-discussed methods, cancelling a command in Linux becomes as easy as issuing them. Remember, mastering Linux commands takes practice. So, keep exploring!
