It's not. See https://pubs.opengroup.org/onlinepubs/9799919799/utilities/sh.html#tag_20_110_16 https://pubs.opengroup.org/onlinepubs/9799919799/utilities/s...

It's not. See https://pubs.opengroup.org/onlinepubs/9799919799/utilities/sh.html#tag_20_110_16 https://pubs.opengroup.org/onlinepubs/9799919799/utilities/s... Applications should note that the standard PATH to the shell cannot be assumed to be either /bin/sh or /usr/bin/sh, and should be determined by interrogation of the PATH returned by getconf PATH, ensuring that the returned pathname is an absolute pathname and not a shell built-in.