Px4-autopilot: Regression with source command

[julianoes]

The recent change (https://github.com/PX4/Firmware/commit/6e1078c96ea22f0a8c64dd6a4956661a086644db) using source instead of . doesn't work on my Arch Linux:

px4 starting.

INFO  [px4] Calling startup script: /bin/sh etc/init.d-posix/rcS 0
/home/julianoes/src/Firmware/build/px4_sitl_default/bin/px4-alias.sh: line 42: `source': is a special builtin
ERROR [px4] Startup script returned with return value: 512

FYI @dagar @davids5

[MaEtUgR]

I have the same with GNU bash, version 5.0.17. I expected other platforms than Cygwin to have these problems since Cygwin doesn't reinvent bash but just keeps it up to date. The last discussion about this topic was: https://github.com/PX4/Firmware/pull/15139#discussion_r486950808

It breaks with https://github.com/PX4/Firmware/commit/185ffe9e13d3b661a4210041cce5bfd22ee1d695 and gives me

/home/maetugr/Firmware/build/px4_sitl_default/tmp/rootfs/etc/init.d/rc.vehicle_setup: line 81: /etc/init.d/rc.interface: No such file or directory
ERROR [px4] Startup script returned with return value: 256

With https://github.com/PX4/Firmware/commit/6e1078c96ea22f0a8c64dd6a4956661a086644db the error changes to

/home/maetugr/Firmware/build/px4_sitl_default/bin/px4-alias.sh: line 42: `source': is a special builtin
ERROR [px4] Startup script returned with return value: 512

What about we try what @bkueng suggests? https://github.com/PX4/Firmware/pull/15139#discussion_r487719343

The main difficulty is that both source and . require an absolute path.
If we need to avoid overriding altogether, we can add a prefix variable, $PWD on POSIX, and / on NuttX: . ${R}etc/init.d/rc.fw_defaults

[dagar]

I'll dig into this later if no one has an immediate solution on hand.

If possible we should also probably favor . over source to maximize compatibility with POSIX sh.

[coderkalyan]

Able to replicate this on Arch as well. Seems to be bash-specific, since Arch and Cygwin symlink bash to /bin/sh while Ubuntu uses dash (which is technically more POSIX compliant). Tested by relinking /bin/sh to dash and it works fine.

[MaEtUgR]

I did some more tests and replacing source with e.g. so in https://github.com/PX4/Firmware/blob/a24488328f175e4657ad449996c42260e4da9c92/platforms/posix/src/px4/common/px4-alias.sh_in#L31 gets rid of the error 512 'source': is a special builtin but then it fails because of rc.vehicle_setup invoking NuttX path scripts -> No such file or directory e.g. with multicopter here: https://github.com/PX4/Firmware/blob/a24488328f175e4657ad449996c42260e4da9c92/ROMFS/px4fmu_common/init.d/rc.vehicle_setup#L80-L84

After reverting those to sh instead of source it works again. So I guess a variable for the path of invoked scripts which is empty on NuttX would make sense right?

[MaEtUgR]

This was resolved by #15970