pty

When to Use PTY

Use pty_spawn instead of bash when:

• The process runs in the background or long-running (dev servers, watchers, etc.)
• The command requires interactive input
• You need to send signals (Ctrl+C, Ctrl+D) mid-run
• You want to tail output while the process is still running

Key Sequences

Action	Data
Ctrl+C (interrupt)	\x03
Ctrl+D (EOF)	\x04
Ctrl+Z (suspend)	\x1a
Enter	\n

Send with pty_write: data="\x03"

Reading Output

Use the pattern parameter in pty_read to filter lines by regex:

pattern="error|ERROR"       # find errors
pattern="ERROR|WARN|FATAL"  # find warnings and errors
pattern="failed.*connection" # more specific match

pattern filters first, then offset/limit apply to the matches — original line numbers are preserved.

Checking Status

• pty_list — see all running/exited sessions
• pty_read with high offset or omit offset to see latest output
• To tail last N lines: offset = totalLines - N

Cleanup

• pty_kill with cleanup=false (default) — stops process, keeps buffer for reading
• pty_kill with cleanup=true — stops process and frees buffer entirely

notifyOnExit

Set notifyOnExit=true to receive a message when the process exits, including exit code and last output line. Useful for build processes where you want to be notified on completion rather than polling.