On 10/05/2019 22:52, Bruce Dubbs via lfs-dev wrote:
> On 5/10/19 3:12 PM, Pierre Labastie via lfs-dev wrote:
>> On 10/05/2019 14:33, Douglas R. Reno via lfs-dev wrote:
>>>
>>> On 5/10/19 2:21 AM, Pierre Labastie via lfs-dev wrote:
>>>> Hi,
>>>>
>>>> I now build the systemd book. I may come back to SysV later, but ATM, I
>>>> want
>>>> to test the BLFS book, and the systemd revision has more thorough coverage
>>>> than SysV.
>>>>
>>>> Since i'm new to systemd, I try various commands. That's how I realized
>>>> there
>>>> was a unit (man-db.timer) for running a daily update of the man database.
>>>> So I
>>>> enabled the unit, and after one day, I received an error concerning the
>>>> associated service.
>>>>
>>>> Investigating, it turns out that /usr/bin/find is hardcoded in the unit,
>>>> and
>>>> we have find in /bin...
>>>>
>>>> I wonder how many units have such harcoded paths.
>>>>
>>>> Looking at man-db source, /usr/bin/find is hardcoded also in
>>>> man-db.service.in. So the following sed is needed:
>>>> sed -i 's@/usr/bin/find@/bin/find@' init/systemd/man-db.service.in
>>>>
>>>> Should we add it to the systemd book?
>>>>
>>>> Pierre
>>>
>>> I've got that sed in my sandbox already, but I think it would be good to go
>>> in
>>> now.
>>>
>>> Please add it :-)
>>>
>>> Not many units are supposed to have hardcoded paths. I don't know if this is
>>> related to some upstreams' initiative to push for a merged / and /usr (where
>>> /lib and /usr/lib are symlinked, /bin and /usr/bin are symlinked, etc). If
>>> it
>>> is, it's a very nasty way to do things. Hardcoded paths are rarely a
>>> requirement.
>>>
>>
>> Hmm, the unit comes from man-db, and was added in last December, to fix a bug
>> in Debian. I do not think that debian is pushing for merging / and /usr. So,
>> no nasty way, just an oversight, I think...
>>
>> As of whether it is possible to use the system PATH, I cannot tell. Somebody
>> with better systemd knowledge than I have should answer: sure it'd be better,
>> but only if we can assess that the PATH is set when running the service...
>>
>> Another possibility, as suggested, would be to symlink to /usr all the
>> executables we move from /usr/{s,}bin to /{s,}bin (as we do for libraries).
>
> Symlinks are a possibility, but I would prefer not doing that if we can.
> Note the that library symlinks are only to the .so files that are used by
> build instructions. These are almost always symlinks anyway. The actual
> libraries are not like libattr.so.1.1.2448 which are not symlinked directly.
> The runtime loader automatically looks in /lib.
>
> I note that our BLFS service files all seem to be using absolute file paths so
> PATH may not be an option.
>
> sed -i /find/s|/usr|| init/systemd/man-db.service.in
>
> Note that this still will work in a merged /usr/bin = /bin system.
OK, let me introduce that sed (although I might use @ instead of |, because
it's more visible to me ;)
Pierre
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