nohup command or "no hangup" is a Linux command used to run a command or a script in the background without interruptions, even if the user who started the command logs out of the system.
nohup command is often used to start long-running processes, such as server processes, that require resources to run even after the user session is terminated.
Linux nohup Command
The basic syntax for using the
nohup command is as follows:
nohup command [arguments] &
command is the program or script, you wish to run in the background, and
arguments denote the parameters to pass to the command to modify the behavior of the
The ampersand symbol
& at the end of the command is used to tell the system to run the process in the background instead of the foreground.
Take for example the command below that runs a python script in the background using the nohup command:
nohup python3 processes.py &
The command above will run the python script in the background and put any output, logs, and error messages in the
nohup.out file. An example output is as shown:
appending output to nohup.out
nohup.out file is created in the current working directory. If you wish to store the output in a different directory, you can use the
-o option as shown in the example below:
nohup -o processes.out python3 process.py &
This will allow the
nohup command to store the output in the
If you want to redirect the standard output (stdout) and standard error (stderr) of a command to different files when using the
nohup command, you can use the
2> operators to redirect each stream to a separate file.
nohup python3 process.py > std.out 2> std.err &
The command above will redirect the standard out to
std.out file and the standard error to
Alternatively, you can use the
&> operator to redirect both stdout and stderr to the same file.
nohup python3 process.py &> logs.out &
This can be useful if you combine both streams' output into a single file for easier monitoring and analysis.
Points to Note
One important thing to note about the
nohup command is that it does not prevent the process from being terminated when the system is shut down or restarted. In such as case, you can look for alternatives such as