tail a log util keywords found or timeout

You could do something like:

sh -c 'echo "$$"; exec tail -f file' | (
  IFS= read -r pid
  timeout 60 sed "/$keyword/q"
  kill -s PIPE "$pid"
)

Unless you have enabled the pipefail option, that will exit with the exit status of kill which should be 0 unless tail has exited of its own (which shouldn't happen in practice).

With pipefail, that would exit with the exit status of tail killed by a SIGPIPE, (which most shells represent with a value of 141). You can always append a || true to force a success exit status.

See also:

• How to exit early on pipe close?
• Grep slow to exit after finding match?
• make tail -f exit on a broken pipe