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.

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.

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 (omit offset to grab the last N lines).

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"}
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