#tail for moonx

Observed native/Wasm P3 profile (2026-09-04): this README is supplementary. The support record is the only capability authority; it lists the repeatable unified-runner results and exclusions.

Print the last lines or bytes of files or stdin:

printf '1\n2\n3\n4\n' | moonx cli/tail -n 2
printf '1\n2\n3\n4\n' | moonx cli/tail -n +3   # from line 3 to the end
moonx cli/tail -n 100 huge.log

Options: -n N last N lines (default 10), -n +K from line K, -c N last N bytes, -c +K from byte K, -q/-v header control, -f/--follow to follow an open file descriptor, and -s SEC/--sleep-interval SEC to set the polling interval (default 1 second).

The observed file paths produced the requested line/byte suffixes and +K forms. Follow mode emits the initial selection, then emits bytes appended to each regular file. A file truncated in place is followed from byte zero. The descriptor remains open across renames, matching tail -f; deleting and recreating a path is not followed, because -F is not implemented.

P3 retained this boundary after rechecking the runtime: no portable cross-target file identity/reopen primitive is available. -F therefore remains a tested status-2 rejection rather than silently behaving like -f.

With no file operand, -f silently reads stdin through EOF and exits, matching the upstream finite-pipe behavior. Regular-file follow is polling-based and works on the native and Wasm targets; it does not require host file-notify APIs.

Source Files

main.mbt

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