I've rebased and updated the patch to include documentation.
Regression tests have been moved to a separate patchfile because error messages will vary by OS and configuration, so we probably can't do a stable regression test, but having them handy at least demonstrates the feature.
Oops, that sample output was from a previous run, should have been:
-- SHELL_EXIT_CODE is undefined \echo :SHELL_EXIT_CODE :SHELL_EXIT_CODE -- bad \! \! borp sh: line 1: borp: command not found \echo :SHELL_EXIT_CODE 127 -- bad backtick \set var `borp` sh: line 1: borp: command not found \echo :SHELL_EXIT_CODE 127 -- good \! \! true \echo :SHELL_EXIT_CODE 0 -- play with exit codes \! exit 4 \echo :SHELL_EXIT_CODE 4 \set var `exit 3` \echo :SHELL_EXIT_CODE 3
This is a POC patch that does that, but doesn't touch on the ON_ERROR_STOP stuff.
I've added some very rudimentary tests, but haven't touched the documentation, because I strongly suspect that someone will suggest a better name for the variable.
