How to Run wget in the Background as a Daemon?

Running wget as a background daemon allows you to initiate large file downloads and safely disconnect from your terminal session without interrupting the transfer. By leveraging built-in wget flags like -b (background) and -q (quiet), or combining the command with standard Unix process management tools like nohup, disown, and screen, you can ensure your downloads continue executing independently in the background. This article covers the most effective methods to daemonize wget, manage the resulting background tasks, and monitor download progress.

Using the Built-In wget Background Flag

The simplest and most direct way to run wget as a daemon-like process is to use its native background option.

• The -b / --background flag: This tells wget to immediately go into the background after the transfer starts.
• Logging: When you use this flag, wget automatically redirects its output to a log file named wget-log in the current directory, unless specified otherwise.

wget -b https://example.com/largefile.zip

If you want to choose a custom name for the log file instead of the default wget-log, combine the background flag with the -o (output log) option:

wget -b -o my_download.log https://example.com/largefile.zip

Using Standard Unix Utilities for Daemonization

If you prefer using standard Linux process management utilities that apply to any command, you have several reliable alternatives.

The nohup Command

The nohup (no hangup) command allows a process to keep running even after you log out or close the terminal. It automatically redirects standard output to nohup.out. To run it in the background, append the ampersand (&) to the end of the command.

nohup wget https://example.com/largefile.zip &

The disown Command

If you already started a wget download normally and realize it is taking too long, you can convert it into a background process:

1. Press Ctrl + Z to pause the current download.
2. Type bg to push the paused job into the background.
3. Type disown -h %1 (replace 1 with the respective job number if different) to detach the job from your terminal shell session.

Monitoring and Managing Your Background Downloads

Once wget is running in the background, you will need ways to check its progress or terminate it if necessary.

Checking Progress

Since background processes do not print to the terminal screen, you can monitor the download progress by viewing the tail end of the log file in real-time:

tail -f wget-log

Killing the Daemon Process

If you need to stop the background download, you must locate its Process ID (PID) and terminate it manually.

1. Find the PID using pgrep:

pgrep wget

2. Kill the process using the retrieved PID:

kill <PID>