[pacman-dev] How does pacman interact with a package's INSTALL script

[Bozhidar Batsov]

Andrew Fyfe wrote:
> lordbad wrote:
>   
>> In the documentation I have read the following:
>>
>>     There are also install files. This PKGBUILD specifies 'foo.install' as the
>> package's install file. Here is an example install file:
>>
>>     post_install() {
>>     /bin/true
>>     }
>>
>>     post_upgrade() {
>>     /bin/true
>>     }
>>
>>     pre_remove() {
>>     /bin/true
>>     }
>>
>>     op=$1
>>     shift
>>
>>     $op "$@"
>>
>>     Here are the function explainations :
>>
>>         * post_install : this script is run right after files are installed, it
>> takes one argument :
>>               o the package version
>>         * post_upgrade : this script is run after all files have been upgraded,
>> it takes two arguments :
>>               o the new package version
>>               o the old package version
>>         * pre_remove : this script is run right before files are removed (stop a
>> daemon for example) and takes one argument :
>>               o the package version
>>
>>     The three lines at the bottom are needed in every install file so that they
>> run properly.
>>
>> But I do not understand how does pacman handle these scripts. Does it source the
>> scripts first and then call the shell functions defined in them with some C
>> function like "system" for example? But if it does so why are the last 3 lines
>> needed - I see little if any need for them. So if anyone can give me some hints
>> on the subject and maybe even mention which of pacman's source files implements
>> this functionality I'd be very grateful. Thanks in advance for your help.
>>
>> Best Regards,
>> Bozhidar
>>
>>
>> _____________________
>> http://www.e-card.bg/
>>
>>
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>>     
>
> The function your looking for is _alpm_runscriptlet() 
> (lib/libalpm/trans.c:567)
>
> http://projects.archlinux.org/git/?p=pacman.git;a=blob;f=lib/libalpm/trans.c;hb=HEAD#l567
>
> Pacman runs 'source <path to file>/.INSTALL <function name> <old ver> 
> <new ver>', the last 3 lines of .INSTALL are needed to get the function 
> name and call it.
>
> Andrew
>
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>   
One more question if I may. Old version and new version have meaning 
only in upgrade context. What should be the value of old version in 
install context and the value of new version in remove context?