Am Freitag 17 August 2018 schrieb Zenaan Harkness: > On Fri, Aug 17, 2018 at 11:25:52AM +0200, to...@tuxteam.de wrote: > > On Fri, Aug 17, 2018 at 06:46:54PM +1000, Zenaan Harkness wrote: > > > 1) > > > Bash man page largely fails to document the true and false builtins > > > AFAICT, except for this sentence just under the heading > > > "^SHELL BUILTIN COMMANDS": > > > > > > The :, true, false, and test builtins do not accept options and do > > > not treat -- specially. > > > > > > But whilst the subsequent list of Bash builtin commands DOES include > > > entries for ":" (the very first entry) and "test", it appears to fail > > > to include entries for "true" and for "false". > > > > > > This would not matter so much except for the following: > > > > > > > > > 2) > > > Why is executing "false" prior to testing it's output, apparently > > > differen to executing "false" in a pipeline, e.g.: > > > > > > $ false > > > $ test $? && echo ok || echo error $? > > > ok > > > $ false blah > > > $ test $? && echo ok || echo error $? > > > ok > > > > Note that after false, > > > > test $? && echo ok || echo error $? > > > > expands (after variable expansion) to > > > > test 0 && echo ok || echo error 0 > > > > ... which ends up saying "ok", because test 0 succeeds :-) > > The only one-arg test which fails is test "". > > Yes, a bit unexpected, due to (a) the shell's evaluation model > > and (b) test's behaviour. > > > > To defend bash's documenters (a bit) its help system provides you > > with tiny snippets of information (try "help false"). > > $ help false > false: false > Return an unsuccessful result. > > Exit Status: > Always fails. > > > That accords with my previous understanding, that the exist status of > running false gives something other than "success" (i.e. zero) - what > am I missing?
Nothing. What Tomás wrote is false (has exit code "1" ;-) This: test $? && echo ok || echo error $? does *not* expand as Tomás said to: test 0 && echo ok || echo error 0 but to: test 1 && echo ok || echo error 1 And "test 1" also succeeds, see Greg's message. Kind regards, Stefan