How to use the command 'nohup' (with examples)
The ’nohup’ command allows you to run a process that will continue to run even if the terminal is closed or the session is ended. It is commonly used in situations where you want to run a long-running process in the background without worrying about it being terminated.
Use case 1: Run a process that can live beyond the terminal
Code:
nohup command argument1 argument2 ...
Motivation:
In certain situations, you might want to start a process that will continue to run even after you close the terminal or log out of your session. Using ’nohup’ ensures that the process doesn’t get terminated when the terminal is closed.
Explanation:
nohup: This command runs a given process in the background and prevents it from being terminated when the terminal is closed.command: This is the actual command you want to run.argument1,argument2, …: These are the arguments required by the command.
Example output:
nohup python my_script.py &
This command will run the ‘my_script.py’ Python script in the background, allowing it to continue running even after the terminal is closed.
Use case 2: Launch ’nohup’ in background mode
Code:
nohup command argument1 argument2 ... &
Motivation:
Running ’nohup’ in the background mode allows you to continue using the current terminal session while the command is running. This is especially useful when you have a long-running process that you want to execute without interrupting your work.
Explanation:
nohup: This command runs a given process in the background and prevents it from being terminated when the terminal is closed.command: This is the actual command you want to run.argument1,argument2, …: These are the arguments required by the command.&: This symbol runs the command in the background.
Example output:
nohup sleep 3600 &
This command launches the ‘sleep’ command with an argument of 3600 (which corresponds to 1 hour) in the background, allowing the sleep process to continue even after the terminal is closed.
Use case 3: Run a shell script that can live beyond the terminal
Code:
nohup path/to/script.sh &
Motivation:
Shell scripts are often used to automate tasks, and in some cases, these scripts might take a long time to complete. By using ’nohup’ to run the shell script, you can ensure that the script continues to run even after the terminal is closed.
Explanation:
nohup: This command runs a given process in the background and prevents it from being terminated when the terminal is closed.path/to/script.sh: This is the path to the shell script you want to execute.
Example output:
nohup /path/to/myscript.sh &
This command runs the ‘myscript.sh’ shell script located at ‘/path/to/’ in the background, allowing it to continue running even after the terminal is closed.
Use case 4: Run a process and write the output to a specific file
Code:
nohup command argument1 argument2 ... > path/to/output_file &
Motivation:
In some cases, you may want to redirect the output of a command to a specific file. By using ’nohup’ with the output redirection, you can ensure that the process continues running even after the terminal is closed while also capturing the output to a file for later analysis.
Explanation:
nohup: This command runs a given process in the background and prevents it from being terminated when the terminal is closed.command: This is the actual command you want to run.argument1,argument2, …: These are the arguments required by the command.>: This symbol redirects the output of the command to the specified file.path/to/output_file: This is the path and file name of the file you want to redirect the output to.
Example output:
nohup python my_script.py > output.txt &
This command runs the ‘my_script.py’ Python script in the background, allowing it to continue running even after the terminal is closed. The output of the script will be redirected and saved to the ‘output.txt’ file.
