The "which" utility is not guaranteed to be installed either, and if it
is, its behavior is not portable either.
Conversely, the "command -v" shell builtin is required to exist in all
POSIX 2008 compliant shells, and is thus guaranteed to work everywhere.
Examples of open-source shells likely to be installed as /bin/sh on
Linux, which implement the 11-year-old standard: ash, bash, busybox,
dash, ksh, mksh and zsh.
A side benefit of using the POSIX portable option is that it requires
neither an external disk executable, nor (because unlike "which", the
exit code is reliable) a subshell fork. This therefore represents a mild
speedup.
Signed-off-by: Eli Schwartz <eschwartz@archlinux.org>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
