luaposix Files

Noteworthy changes in release 37.0 (2026-10-11) [stable]

New Features

• Support for Lua 5.5.

• posix.time.clock_getres and posix.time.clock_gettime are now available on OpenBSD, which has both functions but defines _POSIX_TIMERS to -1.

Incompatible Changes

• When running as root, posix.unistd.setpid with 'u' or 'g' now drops all supplementary groups before setting the user or group id, so that a process dropping its privileges does not keep the access its supplementary groups grant. If dropping them fails, setpid returns nil, a "setgroups: ..." error message and the errnum. Unprivileged callers are unaffected.

• posix.deprecated.uname returns only the formatted string, rather than also leaking the number of substitutions made as a second result.

Bugs Fixed

• posix.deprecated.fadvise accepts file handles again, rather than rejecting every argument with "FILE* expected, got file" whenever typecheck is installed.

• APIs returning nil, an error message and an errnum on failure now always report the errnum of the call that failed. Previously, errno could be clobbered while building the error message, so the errnum was occasionally wrong.

• posix.execx exits the forked child with the right errnum when the command cannot be executed, where it sometimes exited with status 0, as if the command had succeeded.