Master nohup: Run Linux Commands in Background and Capture Output

The nohup command runs a program while ignoring hang‑up signals, so the program continues after the terminal closes. Its output is not shown on the terminal; instead it is appended to nohup.out in the current directory, or to $HOME/nohup.out if the former is unwritable.

Command Syntax

nohup Command [Arg …] [&]

Parameter Details

Command

: the command to execute. Arg: optional arguments, such as output file specifications. &: runs the command in the background, allowing the terminal to exit while the process keeps running.

Redirecting Output and Errors

To send both standard output and standard error to a file (e.g., a.log) while running in the background, use: nohup command > a.log 2>&1 & The redirection 2>&1 means: redirect file descriptor 2 (stderr) to the same destination as file descriptor 1 (stdout), which has already been redirected to a.log.

0 – stdin (standard input)

1 – stdout (standard output)

2 – stderr (standard error)

Background File Download Example

nohup wget https://repo.huaweicloud.com/java/jdk/8u172-b11/jdk-8u172-linux-x64.tar.gz &
# view background jobs
jobs
[1]+  Running                 nohup wget https://repo.huaweicloud.com/java/jdk/8u172-b11/jdk-8u172-linux-x64.tar.gz &

During the download, output is written to nohup.out. You can monitor it in real time with tail -f nohup.out.

Running a Spring Boot Application in Background

nohup java -jar rumenz.jar &

Executing a Bash Command and Capturing Output

nohup bash -c 'cal && ls' > output.txt

This runs the calendar and directory listing, redirects both stdout and stderr to output.txt, and keeps the process alive after the terminal is closed.