Bug#1067804: Possibly redundant "PREREQ" variable + "prereqs" function recommended by the INITRAMFS-TOOLS(7) manpage
Package: initramfs-tools
Version: 0.142
Dear maintainers,
while adapting a workaround for bug 859458 on my systems I noticed a redundant-looking "PREREQ" variable + "prereqs" function recommended by the INITRAMFS-TOOLS(7) manpage (that code is pasted in multiple places in that manpage). See initial details in my message to that bug (the QUESTION part):
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=859458#51
Later I checked the INITRAMFS-TOOLS source code:
- The "get_prereq_pairs" function from the "hook-functions" file (that installs to "/usr/share/initramfs-tools/hook-functions") calls INITRAMFS scripts with the "prereqs" argument. So each script can output a space separated list of prereqs names that is then used to order the scripts in the same directory (see the "cache_run_scripts" function in that "hook-functions" file).
- I did not find any relevant places in the INITRAMFS-TOOLS source code where the "PREREQ" variable or "prereqs" function is used externally (e.g. after sourcing INITRAMFS scripts or for searching in the scripts).
So my initial assumption that the uppercase name of the "PREREQ" variable could mean that it is used globally/externally somewhere else in the INITRAMFS-TOOLS source code was not confirmed (unless I missed something). Same goes for the "prereqs" function, so I really do not know why the INITRAMFS-TOOLS(7) manpage recommends such redundant source code that most INITRAMFS scripts then follow. Some INITRAMFS scripts I looked at however use "PREREQS" instead of "PREREQ" variable and some skip the redundant-looking "PREREQ" variable + "prereqs" function completely.
After my search + testing I now think that it is sufficient to just use the "echo 'PREREQ1 ...'" directly in the case statement (see below). I tested on multiple systems (3 laptops with GUI, 3 VMs with GUI 2 VMs without GUI) that my INITRAMFS scripts without the redundant "PREREQ" variable + "prereqs" function work and my systems boot fine. I also extracted my INITRAMFS with UNMKINITRAMFS and checked the "/main/scripts/*/ORDER" files to confirm that all my INITRAMFS scripts were correctly ordered.
Thus, I think the INITRAMFS-TOOLS(7) manpage should be updated, so that it either explains the purpose of the redundant "PREREQ" variable + "prereqs" function or avoids those redundant parts and uses for example just the case statement:
case "$1" in
prereqs)
echo 'PREREQ1 PREREQ2 PREREQ3 ...'
exit 0;;
esac
Also if "PREREQ" variable + "prereqs" function really is redundant all affected INITRAMFS scripts (= most of them) could be simplified a bit.
Regards,
Jmkr
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