2011-08-08, 13:55(-07), Linda Walsh: [...] > and both 'exit' and 'return' should return error "ERANGE" if "--posix" is > set, and -1 is given. Iinvalid option doesn't make as much sense, in > this situtation, if it was -k or -m, sure...but in this case, it's a fact > that --posix artificially limits exit values apart from what is allowed in > most prog langs (which accept negative, but still return results &0xff), > so for Posix, it's a matter of disallowing a 'normal range', vs. it being > an invalid option.... [...]
POSIX doesn't prevent a shell from accepting -1 (or for doing anything like eject a cd or output an error or turn red upon "return -1"). It just says an *application* should not use "return -1", that is that if one wants to write a portable script, she shouldn't use "return -1". Many POSIX shells accept "return -1" $ ksh93 -c 'f() return -1; f; echo $?' 255 $ pdksh -c 'f() return -1; f; echo $?' -1 $ zsh -c 'f() return -1; f; echo $?' -1 $ posh -c 'f() return -1; f; echo $?' return: invalid option -- '1' 1 $ posh -c 'f() return -- -1; f; echo $?' -1 $ mksh -c 'f() return -1; f; echo $?' mksh: return: -1: unknown option 1 $ mksh -c 'f() return -- -1; f; echo $?' -1 But as you can see the result varies, so one shouldn't use "return -1" if one wants to be portable accross POSIX shells. Also note: $ zsh -c 'f() return -1; f; echo $?' -1 $ zsh -c 'f() return -1; (f); echo $?' 255 That is even in shells that support arbitrary numbers for return, as soon as they are cast to exit status, they are &255ed. -- Stephane
