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I am new to rpm building and for the past week I am trying to code a spec file to install a file on the system only if a specific files is missing. Here is a snippet

%global homedir         %{_var}/lib/test

Source10: main.db
Source11: back.db

%files data
%defattr(-,%{updateuser},%{updateuser},-)
%config(noreplace) %verify(not size md5 mtime) %{homedir}/*.db

I would like to add a condition where, If file /var/lib/test/file1.txt is missing, install /var/lib/test/back.db

I am aware I need to use the %files macro but so far I am not able to figure out how to write the if condition

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  • The question that I have here is whether this is really desirable: your package will be missing a file when someone deletes the file that's not under control of your package? That sounds like you're missing a dependency on some other software package there. Commented Aug 24, 2024 at 0:53
  • concretely, it sounds like you'd want this package to depend on the package that installs /var/lib/test/file1.txt OR the package that contains /var/lib/test/back.db, and put the back.db file in that separate package. Generally, however: Software installation should be fully independent of the data files that are on a system, so even that sounds like a bad idea. Commented Aug 24, 2024 at 0:56

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The %files section is for specifying which files are included in the package, but it doesn’t support conditional logic.

The best way to handle the requirement is through a %post script.

You can check if /var/lib/test/file1.txt is missing using [ ! -e %{homedir}/file1.txt ] and then conditionally install back.db if needed.

The %post section is where such logic belongs, as it runs after the package is installed.

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    Wouldn't [ ! -e /var/lib/test/file1.txt ]; be better? Why assume it needs to be a regular file? Commented Aug 23, 2024 at 8:44
  • yes, [ ! -e /var/lib/test/file1.txt ]; is better Commented Aug 23, 2024 at 9:50
  • @MaxHaase Since the back.db file will be included in the %files section, isn't going to be installed by default? Or should i place back.db file outside %file? Commented Aug 23, 2024 at 12:59
  • Good question! Since back.db is listed in the %files section, it will be installed by default. To handle this conditionally, you can still include back.db in %files (so it’s part of the package), but during %post, you’ll check if file1.txt is missing and only then move or rename back.db to the desired location. There’s no need to remove it from %files; the logic in %post determines if it gets used. Commented Aug 23, 2024 at 13:57

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