what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

[Robert P. J. Day]

there will be many more questions about pkg_postinst (and related)
routines shortly, but digging into these for the first time, i
thought that that test checked whether the routine was being run
at image creation time, or at first-time boot. now i'm not quite
sure what to think after seeing several examples.

what does the test for null or non-null variable "D" mean in
a pkg_postinst routine? and once i figure all this out, i may
very well contribute some enhanced docs for the next confused
person.

rday

Re: [OE-core] what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

[Alexander Kanavin]

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If you show the confusing examples, we could try to figure it out.

Alex

On Wed, 25 Aug 2021 at 22:35, Robert P. J. Day <rpjday@crashcourse.ca>
wrote:

>
> there will be many more questions about pkg_postinst (and related)
> routines shortly, but digging into these for the first time, i
> thought that that test checked whether the routine was being run
> at image creation time, or at first-time boot. now i'm not quite
> sure what to think after seeing several examples.
>
> what does the test for null or non-null variable "D" mean in
> a pkg_postinst routine? and once i figure all this out, i may
> very well contribute some enhanced docs for the next confused
> person.
>
> rday
>
>
> 
>
>

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Re: [OE-core] what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

[Robert P. J. Day]

Quoting Alexander Kanavin <alex.kanavin@gmail.com>:

> If you show the confusing examples, we could try to figure it out.
>
> Alex
>
> On Wed, 25 Aug 2021 at 22:35, Robert P. J. Day <rpjday@crashcourse.ca>
> wrote:
>
>>
>> there will be many more questions about pkg_postinst (and related)
>> routines shortly, but digging into these for the first time, i
>> thought that that test checked whether the routine was being run
>> at image creation time, or at first-time boot. now i'm not quite
>> sure what to think after seeing several examples.
>>
>> what does the test for null or non-null variable "D" mean in
>> a pkg_postinst routine? and once i figure all this out, i may
>> very well contribute some enhanced docs for the next confused
>> person.

   there's no shortage of examples ... here's just one from
recipes-bsp/alsa-state/alsa-state.bb:


pkg_postinst:${PN}() {
         if test -z "$D"       <========
         then
                 if test -x ${sbindir}/alsactl
                 then
                         ${sbindir}/alsactl -g -f  
${localstatedir}/lib/alsa/asound.state restore
                 fi
         fi
}


there's plenty more ... recipes-bsp/keymaps/keymaps_1.0.bb:


pkg_postinst:${PN} () {
         if ${@bb.utils.contains('DISTRO_FEATURES','systemd  
sysvinit','true','false',d)}; then
                 if [ -n "$D" ]; then        <========
                         OPTS="--root=$D"
                 fi
                 systemctl $OPTS mask keymap.service
         fi
}


rday

Re: [OE-core] what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

[Phil Blundell]

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That's testing for offline installation. If $D is not set, it's running on the target.

p.


On 25 August 2021 22:12:22 BST, "Robert P. J. Day" <rpjday@crashcourse.ca> wrote:
>
>Quoting Alexander Kanavin <alex.kanavin@gmail.com>:
>
>> If you show the confusing examples, we could try to figure it out.
>>
>> Alex
>>
>> On Wed, 25 Aug 2021 at 22:35, Robert P. J. Day <rpjday@crashcourse.ca>
>> wrote:
>>
>>>
>>> there will be many more questions about pkg_postinst (and related)
>>> routines shortly, but digging into these for the first time, i
>>> thought that that test checked whether the routine was being run
>>> at image creation time, or at first-time boot. now i'm not quite
>>> sure what to think after seeing several examples.
>>>
>>> what does the test for null or non-null variable "D" mean in
>>> a pkg_postinst routine? and once i figure all this out, i may
>>> very well contribute some enhanced docs for the next confused
>>> person.
>
>   there's no shortage of examples ... here's just one from
>recipes-bsp/alsa-state/alsa-state.bb:
>
>
>pkg_postinst:${PN}() {
>         if test -z "$D"       <========
>         then
>                 if test -x ${sbindir}/alsactl
>                 then
>                         ${sbindir}/alsactl -g -f  
>${localstatedir}/lib/alsa/asound.state restore
>                 fi
>         fi
>}
>
>
>there's plenty more ... recipes-bsp/keymaps/keymaps_1.0.bb:
>
>
>pkg_postinst:${PN} () {
>         if ${@bb.utils.contains('DISTRO_FEATURES','systemd  
>sysvinit','true','false',d)}; then
>                 if [ -n "$D" ]; then        <========
>                         OPTS="--root=$D"
>                 fi
>                 systemctl $OPTS mask keymap.service
>         fi
>}
>
>
>rday
>

-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.

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Re: [OE-core] what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

[Robert P. J. Day]

Quoting Phil Blundell <pb@pbcl.net>:

> That's testing for offline installation. If $D is not set, it's  
> running on the target.
>
> p.

   right, that's exactly what i suspected in my original posting,
i just wanted to make sure, which raises a couple issues.

   first, that distinction doesn't seem to be mentioned in the
docs, so i'll ponder writing something.

   second, is that simply an old form that would be superseded
by using "pkg_postinst_ontarget()" instead?

   anyway, more questions later as i work on some lengthier docs
on this.

rday

Re: [OE-core] what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

[Alexander Kanavin]

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_ontarget() is basically syntactic sugar for $D test, but yes it's the new
preferred form. If you see $D, that means the recipe hasn't been converted.

Alex

On Wed, 25 Aug 2021 at 23:27, Robert P. J. Day <rpjday@crashcourse.ca>
wrote:

>
> Quoting Phil Blundell <pb@pbcl.net>:
>
> > That's testing for offline installation. If $D is not set, it's
> > running on the target.
> >
> > p.
>
>    right, that's exactly what i suspected in my original posting,
> i just wanted to make sure, which raises a couple issues.
>
>    first, that distinction doesn't seem to be mentioned in the
> docs, so i'll ponder writing something.
>
>    second, is that simply an old form that would be superseded
> by using "pkg_postinst_ontarget()" instead?
>
>    anyway, more questions later as i work on some lengthier docs
> on this.
>
> rday
>
>
> 
>
>

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Re: [OE-core] what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

[Robert P. J. Day]

Quoting Phil Blundell <pb@pbcl.net>:

> That's testing for offline installation. If $D is not set, it's  
> running on the target.
>
> p.

   one last query before i head off for dinner ... so what about
pkg_postinst() routines that do double duty, like this one from
dbus_1.12.20.bb:


PACKAGE_WRITE_DEPS += "${@bb.utils.contains('DISTRO_FEATURES','systemd  
sysvinit','systemd-systemctl-native','',d)}"
pkg_postinst:dbus() {
         # If both systemd and sysvinit are enabled, mask the dbus-1  
init script
         if ${@bb.utils.contains('DISTRO_FEATURES','systemd  
sysvinit','true','false',d)}; then
                 if [ -n "$D" ]; then
                         OPTS="--root=$D"
                 fi
                 systemctl $OPTS mask dbus-1.service
         fi

         if [ -z "$D" ] && [ -e /etc/init.d/populate-volatile.sh ] ; then
                 /etc/init.d/populate-volatile.sh update
         fi
}


note how that routine checks its context and, as i recall (but
it's not documented in the docs i'm looking at), i'd swear that
i read somewhere that if a pkg_postinst() routine fails at image
creation time, it was deferred until boot time, which would
explain the above routine checking its runtime context.

   anyway, off for food.

rday

Re: [OE-core] what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

[Alexander Kanavin]

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It used to be that 'exit 1' was the way to defer to boot time, but that was
changed long time ago to not be ambiguous like that and cause a real
failure at build time. Deferring to first boot needs to be explicitly
requested with _ontarget() (you can read the definition for it to see what
really happens, how $D is used and how request to defer is made).

Alex

On Wed, 25 Aug 2021 at 23:51, Robert P. J. Day <rpjday@crashcourse.ca>
wrote:

>
> Quoting Phil Blundell <pb@pbcl.net>:
>
> > That's testing for offline installation. If $D is not set, it's
> > running on the target.
> >
> > p.
>
>    one last query before i head off for dinner ... so what about
> pkg_postinst() routines that do double duty, like this one from
> dbus_1.12.20.bb:
>
>
> PACKAGE_WRITE_DEPS += "${@bb.utils.contains('DISTRO_FEATURES','systemd
> sysvinit','systemd-systemctl-native','',d)}"
> pkg_postinst:dbus() {
>          # If both systemd and sysvinit are enabled, mask the dbus-1
> init script
>          if ${@bb.utils.contains('DISTRO_FEATURES','systemd
> sysvinit','true','false',d)}; then
>                  if [ -n "$D" ]; then
>                          OPTS="--root=$D"
>                  fi
>                  systemctl $OPTS mask dbus-1.service
>          fi
>
>          if [ -z "$D" ] && [ -e /etc/init.d/populate-volatile.sh ] ; then
>                  /etc/init.d/populate-volatile.sh update
>          fi
> }
>
>
> note how that routine checks its context and, as i recall (but
> it's not documented in the docs i'm looking at), i'd swear that
> i read somewhere that if a pkg_postinst() routine fails at image
> creation time, it was deferred until boot time, which would
> explain the above routine checking its runtime context.
>
>    anyway, off for food.
>
> rday
>
>
> 
>
>

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Re: [OE-core] what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

[Robert P. J. Day]

On Thu, 26 Aug 2021, Alexander Kanavin wrote:

> It used to be that 'exit 1' was the way to defer to boot time, but
> that was changed long time ago to not be ambiguous like that and
> cause a real failure at build time. Deferring to first boot needs to
> be explicitly requested with _ontarget() (you can read the
> definition for it to see what really happens, how $D is used and how
> request to defer is made).
>
> Alex

  and that's sort of what i thought, despite what the docs currently
say:

https://www.yoctoproject.org/docs/current/dev-manual/dev-manual.html#new-recipe-post-installation-scripts

"If you do not use this variable, the tools might be missing and
execution of the post-installation script is deferred until first
boot."

  i'll put together some enhanced docs that clear this up, and submit
to docs list.

rday

Re: [OE-core] what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

[Robert P. J. Day]

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On Thu, 26 Aug 2021, Alexander Kanavin wrote:

> It used to be that 'exit 1' was the way to defer to boot time, but
> that was changed long time ago to not be ambiguous like that and
> cause a real failure at build time. Deferring to first boot needs to
> be explicitly requested with _ontarget() (you can read the
> definition for it to see what really happens, how $D is used and how
> request to defer is made).
>
> Alex
>
> On Wed, 25 Aug 2021 at 23:51, Robert P. J. Day <rpjday@crashcourse.ca> wrote:
>
>       Quoting Phil Blundell <pb@pbcl.net>:
>
>       > That's testing for offline installation. If $D is not set, it's 
>       > running on the target.
>       >
>       > p.
>
>          one last query before i head off for dinner ... so what about
>       pkg_postinst() routines that do double duty, like this one from
>       dbus_1.12.20.bb:
>
>
>       PACKAGE_WRITE_DEPS += "${@bb.utils.contains('DISTRO_FEATURES','systemd 
>       sysvinit','systemd-systemctl-native','',d)}"
>       pkg_postinst:dbus() {
>                # If both systemd and sysvinit are enabled, mask the dbus-1 
>       init script
>                if ${@bb.utils.contains('DISTRO_FEATURES','systemd 
>       sysvinit','true','false',d)}; then
>                        if [ -n "$D" ]; then
>                                OPTS="--root=$D"
>                        fi
>                        systemctl $OPTS mask dbus-1.service
>                fi
>
>                if [ -z "$D" ] && [ -e /etc/init.d/populate-volatile.sh ] ; then
>                        /etc/init.d/populate-volatile.sh update
>                fi
>       }

  so, just to confirm the previous tidbits of information (thank you
for your patience), here's my current understanding so i can submit
updated docs:

* pkg_postinst:${PN} is run at image creation time and *only* at image
  creation time; it is no longer deferred to boot time under any
  circumstances(?)

* pkg_postinst_ontarget:${PN} is run at boot time and *only* at boot
  time

* because of the above, there is no value to the numerous legacy
checks of:

  if [ -z "$D" ]
  if [ -n "$D" ]

  or any of its variations (even though, in a lot of cases, they don't
hurt)

* from within pkg_postinst:${PN}, you can still defer some work to
  boot time with "postinst_intercept delay_to_first_boot", although
  isn't this precisely what pkg_postinst_ontarget:${PN} is for, so is
  this postinst_intercept construct still useful?

* PACKAGE_WRITE_DEPS is still necessary to identify non-standard
native tools you might need for any pkg_postinst:${PN} processing

  does all that look about right?

rday

Re: [OE-core] what means the test 'if [ -z "$D" ]' in a pkg_postinst routine?

[Alexander Kanavin]

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On Thu, 26 Aug 2021 at 11:23, Robert P. J. Day <rpjday@crashcourse.ca>
wrote:

>   so, just to confirm the previous tidbits of information (thank you
> for your patience), here's my current understanding so i can submit
> updated docs:
>
> * pkg_postinst:${PN} is run at image creation time and *only* at image
>   creation time; it is no longer deferred to boot time under any
>   circumstances(?)
>

If a package is installed on directly target using a package management
system,
this will run there. Also, if the snippet does contain an explicit call to
the defer to first boot
hook as a part of its logic, then that will happen, and the same code will
run again on first boot.


> * pkg_postinst_ontarget:${PN} is run at boot time and *only* at boot
>   time
>

First boot, or package installation on target.


> * because of the above, there is no value to the numerous legacy
> checks of:
>
>   if [ -z "$D" ]
>   if [ -n "$D" ]
>
>   or any of its variations (even though, in a lot of cases, they don't
> hurt)
>

There might be use cases for doing explicit manual logic where you want
full control over
a) checking what environment you're in
b) doing first boot deferral.
In that case, you want to use $D and the hook directly. But most are legacy
scriptlets that need converting for readability.



> * from within pkg_postinst:${PN}, you can still defer some work to
>   boot time with "postinst_intercept delay_to_first_boot", although
>   isn't this precisely what pkg_postinst_ontarget:${PN} is for, so is
>   this postinst_intercept construct still useful?
>

_ontarget is basically a wrapper for the delay to first boot hook. It might
be useful
for manual control, as explained above.


> * PACKAGE_WRITE_DEPS is still necessary to identify non-standard
> native tools you might need for any pkg_postinst:${PN} processing
>

Yes.

Alex

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