request: builtin hash - exit status 1 on search failure

[dicktyr]

both bash and dash return exit status 1 if PATH search fails
but ksh always returns exit status 0

differentiating exit status enables

hash cmd && cmd ...

rather than

[[ -n type -p cmd ]] && cmd ...

[McDutchie]

ksh93 already has a way to do what you want:

whence -pq cmd && cmd ...

As for hash, the behaviour on other POSIXy shells is:

• mksh always returns 0, like ksh93.
• bash, dash, FreeBSD sh, NetBSD sh, yash and zsh not only return status 1 on command not found, but also print an error message.

POSIX says that hash shall return non-zero on error, but does not define 'command not found' as an error condition — whereas, for command -v, it does.

Still, I could change ksh 93u+m's behaviour for hash to match that of all the non-ksh shells (in which case we should also add the error message), but it would have to be for version 1.1 and up as the change is not backward compatible.