How does debian/ubuntu knows a package has a updated version





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If my understanding is good, with apt update, Debian download a release file and with this file, it can tell if a package needs to be upgraded and with which dependencies. How does it do this? Th release file seems to be just a list of hashes so I don't quite understand.



Sorry, I don't have a very good English.










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    If my understanding is good, with apt update, Debian download a release file and with this file, it can tell if a package needs to be upgraded and with which dependencies. How does it do this? Th release file seems to be just a list of hashes so I don't quite understand.



    Sorry, I don't have a very good English.










    share|improve this question







    New contributor




    thomas is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      If my understanding is good, with apt update, Debian download a release file and with this file, it can tell if a package needs to be upgraded and with which dependencies. How does it do this? Th release file seems to be just a list of hashes so I don't quite understand.



      Sorry, I don't have a very good English.










      share|improve this question







      New contributor




      thomas is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.












      If my understanding is good, with apt update, Debian download a release file and with this file, it can tell if a package needs to be upgraded and with which dependencies. How does it do this? Th release file seems to be just a list of hashes so I don't quite understand.



      Sorry, I don't have a very good English.







      ubuntu debian apt






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      thomas is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      asked 4 hours ago









      thomasthomas

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          Whilst apt update can download one or more Release files, the primary files it is downloading are Packages file(s). Those files contain the full list of available packages, their versions, and other metadata (like dependencies). Once apt has a list of available packages and their versions, it is a straightforward matter of comparison to determine which packages have versions newer than those currently installed.






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          • Thanks a lot for this.

            – thomas
            3 hours ago



















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          Package lists are the Packages and Sources files. These contain the debian/control file content for every package in the repository. From these metadata APT can determine a dependency solution.



          Releases is a description of the entire archive and signature data.



          Debian reference manual, Chapter 2. Debian package management






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            2 Answers
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            Whilst apt update can download one or more Release files, the primary files it is downloading are Packages file(s). Those files contain the full list of available packages, their versions, and other metadata (like dependencies). Once apt has a list of available packages and their versions, it is a straightforward matter of comparison to determine which packages have versions newer than those currently installed.






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            • Thanks a lot for this.

              – thomas
              3 hours ago
















            2














            Whilst apt update can download one or more Release files, the primary files it is downloading are Packages file(s). Those files contain the full list of available packages, their versions, and other metadata (like dependencies). Once apt has a list of available packages and their versions, it is a straightforward matter of comparison to determine which packages have versions newer than those currently installed.






            share|improve this answer
























            • Thanks a lot for this.

              – thomas
              3 hours ago














            2












            2








            2







            Whilst apt update can download one or more Release files, the primary files it is downloading are Packages file(s). Those files contain the full list of available packages, their versions, and other metadata (like dependencies). Once apt has a list of available packages and their versions, it is a straightforward matter of comparison to determine which packages have versions newer than those currently installed.






            share|improve this answer













            Whilst apt update can download one or more Release files, the primary files it is downloading are Packages file(s). Those files contain the full list of available packages, their versions, and other metadata (like dependencies). Once apt has a list of available packages and their versions, it is a straightforward matter of comparison to determine which packages have versions newer than those currently installed.







            share|improve this answer












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            answered 3 hours ago









            womblewomble

            85.8k18145204




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            • Thanks a lot for this.

              – thomas
              3 hours ago



















            • Thanks a lot for this.

              – thomas
              3 hours ago

















            Thanks a lot for this.

            – thomas
            3 hours ago





            Thanks a lot for this.

            – thomas
            3 hours ago













            1














            Package lists are the Packages and Sources files. These contain the debian/control file content for every package in the repository. From these metadata APT can determine a dependency solution.



            Releases is a description of the entire archive and signature data.



            Debian reference manual, Chapter 2. Debian package management






            share|improve this answer




























              1














              Package lists are the Packages and Sources files. These contain the debian/control file content for every package in the repository. From these metadata APT can determine a dependency solution.



              Releases is a description of the entire archive and signature data.



              Debian reference manual, Chapter 2. Debian package management






              share|improve this answer


























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                1







                Package lists are the Packages and Sources files. These contain the debian/control file content for every package in the repository. From these metadata APT can determine a dependency solution.



                Releases is a description of the entire archive and signature data.



                Debian reference manual, Chapter 2. Debian package management






                share|improve this answer













                Package lists are the Packages and Sources files. These contain the debian/control file content for every package in the repository. From these metadata APT can determine a dependency solution.



                Releases is a description of the entire archive and signature data.



                Debian reference manual, Chapter 2. Debian package management







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                answered 3 hours ago









                John MahowaldJohn Mahowald

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