openclaw/docs/gateway/background-process.md

summary, read_when, title

summary	read_when	title
Background exec execution and process management	Adding or modifying background exec behavior Debugging long-running exec tasks	Background Exec and Process Tool

Background Exec + Process Tool

OpenClaw runs shell commands through the exec tool and keeps long‑running tasks in memory. The process tool manages those background sessions.

exec tool

Key parameters:

• command (required)
• yieldMs (default 10000): auto‑background after this delay
• background (bool): background immediately
• timeout (seconds, default 1800): kill the process after this timeout
• elevated (bool): run on host if elevated mode is enabled/allowed
• Need a real TTY? Set pty: true.
• workdir, env

Behavior:

• Foreground runs return output directly.
• When backgrounded (explicit or timeout), the tool returns status: "running" + sessionId and a short tail.
• Output is kept in memory until the session is polled or cleared.
• If the process tool is disallowed, exec runs synchronously and ignores yieldMs/background.
• Spawned exec commands receive OPENCLAW_SHELL=exec for context-aware shell/profile rules.

Child process bridging

When spawning long-running child processes outside the exec/process tools (for example, CLI respawns or gateway helpers), attach the child-process bridge helper so termination signals are forwarded and listeners are detached on exit/error. This avoids orphaned processes on systemd and keeps shutdown behavior consistent across platforms.

Environment overrides:

• PI_BASH_YIELD_MS: default yield (ms)
• PI_BASH_MAX_OUTPUT_CHARS: in‑memory output cap (chars)
• OPENCLAW_BASH_PENDING_MAX_OUTPUT_CHARS: pending stdout/stderr cap per stream (chars)
• PI_BASH_JOB_TTL_MS: TTL for finished sessions (ms, bounded to 1m–3h)

Config (preferred):

• tools.exec.backgroundMs (default 10000)
• tools.exec.timeoutSec (default 1800)
• tools.exec.cleanupMs (default 1800000)
• tools.exec.notifyOnExit (default true): enqueue a system event + request heartbeat when a backgrounded exec exits.
• tools.exec.notifyOnExitEmptySuccess (default false): when true, also enqueue completion events for successful backgrounded runs that produced no output.

process tool

Actions:

• list: running + finished sessions
• poll: drain new output for a session (also reports exit status)
• log: read the aggregated output (supports offset + limit)
• write: send stdin (data, optional eof)
• kill: terminate a background session
• clear: remove a finished session from memory
• remove: kill if running, otherwise clear if finished

Notes:

• Only backgrounded sessions are listed/persisted in memory.
• Sessions are lost on process restart (no disk persistence).
• Session logs are only saved to chat history if you run process poll/log and the tool result is recorded.
• process is scoped per agent; it only sees sessions started by that agent.
• process list includes a derived name (command verb + target) for quick scans.
• process log uses line-based offset/limit.
• When both offset and limit are omitted, it returns the last 200 lines and includes a paging hint.
• When offset is provided and limit is omitted, it returns from offset to the end (not capped to 200).

Examples

Run a long task and poll later:

{ "tool": "exec", "command": "sleep 5 && echo done", "yieldMs": 1000 }

{ "tool": "process", "action": "poll", "sessionId": "<id>" }

Start immediately in background:

{ "tool": "exec", "command": "npm run build", "background": true }

Send stdin:

{ "tool": "process", "action": "write", "sessionId": "<id>", "data": "y\n" }