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Package Management Systems

Types of packages​

  • Binary: compiled executables per architecture.
  • Source: packages with source code that can be compiled for particular architecture.

Packaging Tool Levels​

  • High: automatic package dependency resolution.

    • apt
    • yum

  • Low: manual dependency and installation of package dependencies.

    • rpm (Red Hat Package Manager)

      • By default, manages local repository packages.

      • Binary package format <name>-<version>-<release>.<distro>.<architecture>.rpm.

      • Source package format <name>-<version>-<release>.<distro>.src.rpm.

      • database is held in /var/lib/rpm

      • helper scripts are located in /usr/lib/rpm/.

      • can create rpmrc file to modify rpm defaults. rpm looks for the file in order /usr/lib/rpm/rpmrc, /etc/rpmrc, ~/.rpmrc and reads all of them. Can use --rcfile as an argument to specify as well.

      • Useful query commands

        # Version of package?
        rpm -q bash

        # Which package did file come from?
        rpm -qf /bin/bash

        # What files were installed by the package?
        rpm -ql bash

        # Show package info
        rpm -qi bash

        # Show package info from file
        rpm -qip foo-1.0.0-1.noarch.rpm

        # List all packages installed
        rpm -qa

        # List package dependencies
        rpm -qp --requires some_package-0.0.1-noarch.rpm

        # What installed package provides a particular requisite package
        rpm -q --whatprovides libc.so.6

        # Verify package matches `rpm` database

        rpm -V bash

        # Install a package
        rpm -i bash-4.4.19-8.el8_0.x86_64

        # Dry run erase a package
        rpm -e nano --test

        # Update package(s)
        rpm -U bash-4.4.19-10.el8.x86_64.rpm another_pkg

        # Revert to older package
        rpm -U --oldpackage bash-4.3.19-10.el8.x86_64.rpm

        # Upgrade multiple packages in directory
        rpm -F *.rpm

        # Install kernel (don't upgrade since it removes older kernels!)
        rpm -ivh kernel-{version}.{arch}.rpm

        # Convert .rpm to cpio
        rpm2cpio foobar.rpm > foobar.cpio

        # List files in RPM package
        rpm2cpio -qlp bash-XXX.rpm

    • dpkg (Debian Package Manager)

      • *.deb prefix.

      • Database location /var/lib/dpkg.

      • Standard naming format <name>_<version>-<revision_number>_<architecture>.deb.

      • A source package consists of:

        • unmodified sourcecode in .tar.gz format.
        • A description file .dsc.
        • Patch/additional files .debian.tag.gz or .diff.gz.

      • Commands

        # List all installed packages
        dpkg -l 

        # List files installed in package
        dpkg -L curl

        # Show information about installed package
        dpkg -p udev

        # See what package owns a file
        dpkg -S /etc/init/networking.conf

        # Show file status
        dpkg -s wget

        # Verify installed package integrity
        dpkg -V wget

        # Install/upgrade package
        dpkg -i foobar.deb

        # Remove package (- config)
        dpkg -r package

        # Purge package (+ config)
        dpkg -P package

Package Sources​

Distros have package repositories that contain all information about most up-to-date software.

Revision Control Systems​

git has two data strcutures:

  • object database (`
  • /.git/objects`:
    • Blobs: chunks of binary data containing file contents. Can use git cat-file to translate binary data to human-friendly text.
    • Trees: sets of blobs that construct the directory structure.
    • Commits: changesets describing tree snapshots.
  • directory cache : captures the current state of the directory tree.