问设置-eo管道故障在ksh和bash上不同

EN

# x
set -eo pipefail
false | true
echo "done: $?" # reached in ksh, unexpected
false
echo "done2" # not reached in either shell, as expected

bash x        # prints nothing, as expected
ksh x         # done: 1
ksh --version # ... 93u+ 2012-08-01

-bash-5.0$ zsh -c 'set -eo pipefail; false | true; exit 2' ; echo $?
1
-bash-5.0$ ksh -c 'set -eo pipefail; false | true; exit 2'; echo $?
2
-bash-5.0$ bash -c 'set -eo pipefail; false | true; exit 2' ; echo $?
1

-e    Unless contained in a ⎪⎪ or && command, or the command
      following an if while or until command or in the
      pipeline following !, if a command has a non-zero exit  # Pipeline does not follow !
      status, execute the ERR trap, if set, and exit.  This   # Pipeline has a non-zero exit status
      mode is disabled while reading profiles.

pipefail
      A pipeline will not complete until all
      components of the pipeline have completed, and
      the return value will be the value of the last
      non-zero command to fail or zero if no command
      has failed.