Unclear Whether the earlier warning against using Bash for cat, head, tail, sed, awk or echo was removed from this prompt is not clear.
What
The Bash tool is how Claude runs commands in your terminal. The instructions Claude receives for it were rewritten in this release. The change appears in the main command-line and SDK prompts, and in the command-security-review and command-team-onboarding prompts.
- The timeout line now says the limit of 600000ms (10 minutes) is for a foreground command, one Claude waits on. The default is still 120000ms (2 minutes).
- The
run_in_backgroundoption is now explained as running the command detached: "it keeps running across turns and re-invokes you when it exits". One version adds "No&needed." - The earlier wording is kept in one form: use it only if you don't need the result immediately and are OK being notified when the command completes later.
In the capture taken under this release, the longest Bash description is 10,061 characters.
Why
These are Claude's own instructions, so the wording shapes how it uses background commands. Claude is now told plainly that a background command keeps running after its turn ends and that it will be brought back when the command finishes, and that it should not add & itself.
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
* **No background subagents from in-process teammates**: an in-process teammate's own subagents run in the foreground, because a teammate's background work can't outlive the lead's process. Claude Code returns an error when a teammate spaw…agent-teams see the edit
| `status` | string | `"completed"` | `"completed"` for foreground subagents, `"async_launched"` for background subagents. Subagents run in the background by default, so an Agent call that omits `run_in_background` also produces `"async_la…hooks see the edit
Whether the earlier warning against using Bash for `cat`, `head`, `tail`, `sed`, `awk` or `echo` was removed from this prompt is not clear.
Anthropic's documentation has since written up run_in_background, on Hooks reference.
Changed background Bash and PowerShell commands to stop after a time limit (their timeout with run_in_background, default 30 min, max 2 h)…