Make use of command return codes

[ecklm]

The main command's return code might be an extremely valuable
information, therefore it needs to be returned when go-init exits. Pre
and post command exit codes may as well be valuable, therefore it is
also worth at least printing them.

In collaboration with: Dénes Fodor fodor.denes@balasys.hu

Resolves: #1

---

In case you want some examples:

# Non-zero exit code everywhere
$ ./go-init -pre "./exittest 5" -main "./exittest 3" -post "./exittest 7" ; echo $?
2020/06/05 14:31:10 [go-init] Pre-start command launched : ./exittest 5
2020/06/05 14:31:10 [go-init] Pre-start command exited with code 5
2020/06/05 14:31:10 [go-init] Main command launched : ./exittest 3
2020/06/05 14:31:10 [go-init] Main command exited with code 3
2020/06/05 14:31:10 [go-init] Post-stop command launched : ./exittest 7
2020/06/05 14:31:10 [go-init] Post-stop command exited with code 7
3

# Zero exit code in -main, non-zero elsewhere
$ ./go-init -pre "./exittest 5" -main "./exittest 0" -post "./exittest 7" ; echo $?
2020/06/05 14:31:15 [go-init] Pre-start command launched : ./exittest 5
2020/06/05 14:31:15 [go-init] Pre-start command exited with code 5
2020/06/05 14:31:15 [go-init] Main command launched : ./exittest 0
2020/06/05 14:31:15 [go-init] Main command exited with code 0
2020/06/05 14:31:15 [go-init] Post-stop command launched : ./exittest 7
2020/06/05 14:31:15 [go-init] Post-stop command exited with code 7
0

# Error in the command specification in -main
$ ./go-init -pre "./exittest 5" -main "exittest 3" -post "./exittest 7" ; echo $?
2020/06/05 14:31:00 [go-init] Pre-start command launched : ./exittest 5
2020/06/05 14:31:00 [go-init] Pre-start command exited with code 5
2020/06/05 14:31:00 [go-init] Main command launched : exittest 3
2020/06/05 14:31:00 [go-init] Main command exited with code -1
2020/06/05 14:31:00 [go-init] exec: "exittest": executable file not found in $PATH
2020/06/05 14:31:00 [go-init] Post-stop command launched : exittest 7
2020/06/05 14:31:00 [go-init] Post-stop command exited with code -1
2020/06/05 14:31:00 [go-init] exec: "exittest": executable file not found in $PATH
255

# Error in the command specification somewhere else
[ecklm@ecklm-balasys go-init ]$ ./go-init -pre "xyz" -main "./exittest 0" -post "./exittest 0" ; echo $?
2020/06/05 14:34:25 [go-init] Pre-start command launched : xyz
2020/06/05 14:34:25 [go-init] Pre-start command exited with code -1
2020/06/05 14:34:25 [go-init] exec: "xyz": executable file not found in $PATH
255

Where exittest has the following content:

#! /bin/bash

exit $1

[ecklm]

By the way, as this is a significant change in the interface, I'd suggest changing the version number to 0.1.0 in the CI.

[pablo-ruth]

Hi,
I'm sorry, as mentioned in the Readme, I don't maintain this project anymore. Please feel free to fork!