bg

Overview

bg resumes a stopped job in the background so it continues running without occupying the terminal. It is part of interactive shell job control (bash/zsh), together with fg, jobs, Ctrl-Z, and &.

Job control is per-shell: background jobs are not the same as systemd services or nohup daemons.

Syntax

bg [job_spec ...]

With no argument, resumes the current job (%+).

Job specification

Spec	Meaning
%n	Job number n
%string	Job whose command begins with string
%?string	Job whose command contains string
%% or %+	Current job
%-	Previous job

Common Options

None significant — bg is a shell builtin. See help bg.

Examples with Explanations

Suspend then background

# start a long command in foreground
find / -xdev -name '*.log' 2>/dev/null
# press Ctrl-Z  → Stopped
bg
# continues in background
jobs -l

Start in background directly

make -j$(nproc) &
jobs

& starts background immediately; bg is for jobs already stopped.

Specific job

jobs
bg %1
bg %find

Multiple jobs

bg %1 %2

Typical workflow

gzip -k huge.img
# Ctrl-Z
bg
# continue using the shell
jobs -l
fg %1          # bring back if needed

Disown / survive hangup

# after bg:
disown %1
# or start with:
nohup longcmd &
# or use tmux/systemd for real persistence

Not for scripts by default

# non-interactive shells often have job control off
set -m              # monitor mode (enable job control) if needed
sleep 30 &
jobs

Prefer explicit background with & and wait in scripts rather than bg.

Notes / Pitfalls

• Only works with job control enabled and jobs owned by this shell.
• Background jobs writing to the terminal can interleave messily — redirect stdout/stderr.
• bg on an already running background job is a no-op / error depending on shell.
• Closing the terminal may SIGHUP jobs unless disown/nohup/tmux/systemd.
• Don’t confuse with systemd bg — there is none; use units for services.

2026-relevant notes

• For anything important, prefer tmux/systemd-run/nohup over bare bg.
• Desktop environments may use their own session management; servers still rely on classic job control daily.
• Pipeline job control can be surprising — know whether the whole pipeline is one job.

Related Commands

• fg — resume in foreground
• jobs — list jobs
• Ctrl-Z / kill -STOP — stop
• disown — detach from shell job table
• nohup — ignore hangup
• tmux / screen — persistent sessions
• wait — wait for background PIDs/jobs

Additional Resources

• help bg, man bash (JOB CONTROL)