How do I keep a process running after logout?

Start the process in background with '&', then use 'disown' to remove it from job control, or use 'nohup' when starting the process.

What's the difference between disown and nohup?

disown removes existing jobs from shell control, while nohup starts processes immune to hangup signals from the beginning.

disown Command

Q: What does the disown command do?

The disown command removes jobs from the shell's job table, preventing the shell from sending SIGHUP signals to those processes when the shell exits.

The disown command removes jobs from the shell's job table, preventing the shell from sending SIGHUP signals to those processes when the shell exits. This allows processes to continue running after logout.

Syntax

disown [-ar] [-h] [jobspec ...]

Description

The disown command removes jobs from the shell's active job list. When a job is disowned, the shell will not send a SIGHUP signal to it when the shell terminates, allowing the process to continue running independently.

Key features:

Removes jobs from shell job control
Prevents SIGHUP signals on shell exit
Allows processes to survive logout
Works with background jobs
Built-in shell command

Common Options

Option	Description
`-a`	Remove all jobs from the job table
`-r`	Remove only running jobs
`-h`	Mark jobs so they don't receive SIGHUP (but keep in job table)
`jobspec`	Specific job to disown (e.g., %1, %2)

Job Specifications

Format	Description
`%n`	Job number n
`%string`	Job whose command begins with string
`%?string`	Job whose command contains string
`%%` or `%+`	Current job (most recent)
`%-`	Previous job

Examples

Disown most recent job

disown

Removes the most recent job from the job table

Disown specific job

disown %1

Removes job number 1 from the job table

Disown all jobs

disown -a

Removes all jobs from the job table

Disown only running jobs

disown -r

Removes only currently running jobs

Mark job to ignore SIGHUP

disown -h %1

Marks job 1 to ignore SIGHUP but keeps it in job table

Complete workflow example

                        # Start a long-running process in background
                        sleep 3600 &
                        [1] 12345
                        
                        # Check jobs
                        jobs
                        [1]+  Running    sleep 3600 &
                        
                        # Disown the job
                        disown %1
                        
                        # Check jobs again (job is gone)
                        jobs
                        # (no output - job removed from table)
                        
                        # Process continues running even after logout
                        ps aux | grep sleep
                        user  12345  0.0  0.0   7648   616 ?    S    10:30   0:00 sleep 3600
                    

Complete example of disowning a background process

Disown by command name

disown %sleep

Disowns the job whose command starts with "sleep"

Disown job containing string

disown %?backup

Disowns the job whose command contains "backup"

Start and immediately disown

long-running-command & disown

Starts a command in background and immediately disowns it

Multiple job disown

disown %1 %2 %3

Disowns multiple specific jobs

Common Use Cases

Long-running processes: Keep processes running after SSH logout
Background services: Start temporary services that should persist
Data processing: Run lengthy data processing jobs independently
Downloads: Continue downloads after closing terminal
Monitoring: Run monitoring scripts that should survive session

Comparison with Alternatives

Command	When to Use	Behavior
`disown`	After starting a process	Removes from job control
`nohup`	Before starting a process	Immune to SIGHUP from start
`screen`	Interactive sessions	Detachable terminal sessions
`tmux`	Multiple terminal sessions	Terminal multiplexer