Installing Software, Part 2: Package Managers


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This second presentation in the series looks at the package managers available for downloading and installing Linux software

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Installing Software, Part 2: Package Managers

  1. 1. Installing Software, Part 2 Kevin B. O'Brien Washtenaw Linux Users Group Washtenaw Linux Users Group 1
  2. 2. Package Tool Levels 1 GUI Package Tool High-Level Package Tool Low-Level Package Tool Washtenaw Linux Users Group 2
  3. 3. Package Tool Level 2 ● For newcomers, the easiest level to work at is the GUI Package Tool ● That is what we looked at in the first presentation ● But a GUI is just a front-end for what you can do on the command line ● The command line is much more powerful Washtenaw Linux Users Group 3
  4. 4. Package Tool Level 3 ● Anything you can do with a GUI you can do on a command line ● But the command line will let you do more than the GUI will ● When the GUI has trouble with a package install you will generally need to use the command line to fix the problem ● These are all administrative tasks, so run them as root or use sudo Washtenaw Linux Users Group 4
  5. 5. Two flavors ● While we looked at three GUI tools in the previous presentation, here we will only look at two sets of command line tools ● They are YUM (and RPM) and APT (and DPKG) ● They work with RPM and Debian packages respectively ● There are others, but once you learn the basic principles you can pick up the others pretty easily shouldLinux Users need to Washtenaw you Group 5
  6. 6. RPM ● RPM stands for Red Hat Package Manager ● Red Hat is the major distro for corporate and server center environments ● Many major distros have adopted RPM as well: OpenSUSE, Mandriva, etc. ● RPM can be run by itself from the command line, or you can use an intermediate tool like YUM (Yellowdog Updater, Modified) Washtenaw Linux Users Group 6
  7. 7. YUM 1 “Yum is an automatic updater and package installer/remover for rpm systems. It automatically computes dependencies and figures out what things should occur to install packages. It makes it easier to maintain groups of machines without having to manually update each one using rpm.” Washtenaw Linux Users Group 7
  8. 8. YUM 2 ● Although there are GUI front-ends for YUM, we will focus on the command line use (PackageKit, which we covered in the first presentation, is the default for Fedora since version 9) ● YUM is pretty simple ● To install a program, type yum install <package_name> ● Remember that all of these commands must be run as root or using sudo Washtenaw Linux Users Group 8
  9. 9. YUM 3 ● What happens when you enter this command? ● YUM checks the database of packages available in the repositories it knows about ● If it finds the package, it then checks the headers of the package to discover any dependencies ● It then prepares to download and install all of the files needed to get your package up and running Washtenaw Linux Users Group 9
  10. 10. It's Not There? ● What if you get an error that there is no such package? ● That means that it is not in any of the repositories that your system knows about ● Do a Google search (or Bing, if you really must) to find the repository. Many companies maintain repos for the major two systems (e.g. Google) ● If that does not work, you may need to resort to more drastic measures, covered in a future presentation Washtenaw Linux Users Group 10
  11. 11. Repositories ● We covered this in some detail in the previous presentation ● These are online collections of software packages that you can download and install ● You will have the best results using repositories that are designed for your distro ● These can be created by the distro itself, or by third-parties (e.g. Miro) Washtenaw Linux Users Group 11
  12. 12. Repositories 2 ● Adding a repository is easiest with the GUI front-ends because they do so much of it for you ● But you can add one if you know how to use a text editor Washtenaw Linux Users Group 12
  13. 13. Adding a repo 1 ● Example, adding Google's Linux repo ● As root, add the following to a file called google.repo in /etc/yum.repos.d/: [google] name=Google – i386 baseurl= table/i386 enabled=1 gpgcheck=1 ● yum.html Washtenaw Linux Users Group 13
  14. 14. Adding a repo 2 ● So, you first need to be able to run a text editor as root (or by using sudo) ● Then you need to create a file in a specified directory (/etc/yum.repos.d/) ● The file needs to have a name that identifies it, and an extension of *.repo. You can pick the name you want to use, but it should be descriptive enough that you can find it if needed. Washtenaw Linux Users Group 14
  15. 15. Adding a repo 3 ● Finally, you have to enter some structured information into this text file ● The last line, gpgcheck=1, will cause it to automatically download and add a GPG signature while you are installing it Washtenaw Linux Users Group 15
  16. 16. Adding a Repo 4 ● To check, try adding the Google repo as shown above ● Then open PackageKit, and update your package lists ● Then run a search for “google” ● You will see lots of available packages ● Then check your Software Sources, and see it listed Washtenaw Linux Users Group 16
  17. 17. Adding a Repo 5 Washtenaw Linux Users Group 17
  18. 18. YUM 4 ● So, with the new Google repository added, let's say you wanted to install the new Google browser, Chrome, all you do is yum install google-chrome ● And if you later change your mind, it is simply yum remove google-chrome Washtenaw Linux Users Group 18
  19. 19. Updating Repositories ● You want to keep your information on what is in the repos up-to-date ● You can get a manual update any time by entering yum update ● To automate this more, edit the file /etc/yum/yum-updatesd.conf (Note: This file may not exist at first, so you would need to create it with a text editor) Washtenaw Linux Users Group 19
  20. 20. yum-updatesd.conf 1 ● This is the configuration file for yum- updatesd ● Instructions can be found at updatesd.conf ● You can set the interval to check the repos here Washtenaw Linux Users Group 20
  21. 21. yum-updatesd.conf 2 ● You can set it to notify you in several ways; probably e-mail will be the easiest. ● You could set it to install updates automatically, or to just download them automatically Washtenaw Linux Users Group 21
  22. 22. YUM upgrades 1 ● Generally speaking, update means to check the info on what the latest versions are of your packages ● It is only informational ● Upgrade means to actually download and install the newest version Washtenaw Linux Users Group 22
  23. 23. YUM upgrades 2 ● So, if you learned (through an update) there was a new version of Google Chrome that you wanted to install you would type yum upgrade google-chrome Washtenaw Linux Users Group 23
  24. 24. YUM process summarized 1 ● You can add repos to your collection ● You can then update the info in them to make sure it is current, and set this up to happen automatically in yum- updatesd.conf ● You can upgrade packages ● You can install new packages Washtenaw Linux Users Group 24
  25. 25. YUM process summarized 2 ● You can remove ones you don't need any more ● And all of this can be done at the command line Washtenaw Linux Users Group 25
  26. 26. YUM resources ● /103/DELICIOUS ● ● Washtenaw Linux Users Group 26
  27. 27. APT, the Debian way ● The other major package management system is APT (Advanced Package Tool), which is used in Debian and related distros (Ubuntu being a major one here) ● This works a lot like yum, which is not surprising since they are doing the same things Washtenaw Linux Users Group 27
  28. 28. Repositories ● Just as with YUM, you need to maintain your repository information when using APT ● This is kept in a file /etc/apt/sources.list ● Here, each repo has a line in this single file ● For example, here is the main Debian repo deb stable main contrib non-free Washtenaw Linux Users Group 28
  29. 29. Repository lines 1 ● The first entry “deb”, says that is a repo containing binary packages for Debian ● If they contained source code, the first item would be “deb-src” ● In either case, this is followed by the address of the repo. These are most often http, but can also be ftp, ssh, or point to a local file Washtenaw Linux Users Group 29
  30. 30. Repository Lines 2 ● This is followed by the name of the distribution; in Debian is might be “stable”, in Ubuntu it might be “jaunty”. ● The remaining fields are optional, but add some more description Washtenaw Linux Users Group 30
  31. 31. Managing Repositories 1 ● Adding a repo is as simple as adding a line to /etc/apt/sources.list ● As root, or using sudo, use a text editor to add a line to the list to add a repository ● To remove one, you can just delete the line, but it is easier and safer to just comment out the line by putting “# “ in front of the line (pound sign and a space) ● To re-enable the repo, just remove the comment Washtenaw Linux Users Group 31
  32. 32. Managing Repositories 2 ● As with YUM, you want to keep everything up-to-date ● APT keeps information about the contents of each repository, and about what packages you have installed, in a local database Washtenaw Linux Users Group 32
  33. 33. Managing Repositories 3 ● You can update the information about each repo with apt-get update ● Remember, this is an administrative task, so either run as root or use sudo for all commands Washtenaw Linux Users Group 33
  34. 34. Packages 1 ● You can install packages (e.g. Google Chrome) by apt-get install google-chrome ● If you later change your mind, just apt-get remove google-chrome ● As with YUM, if you get an error that the package could not be found, you should do a search to see if there is a repository that contains it Washtenaw Linux Users Group 34
  35. 35. Packages 2 ● Many companies will set up repositories for the major distros (e.g. Google) Washtenaw Linux Users Group 35
  36. 36. More APT 1 ● If you damage an install, or just think something went wrong, you can force a reinstall apt-get --reinstall install pine Washtenaw Linux Users Group 36
  37. 37. More APT 2 ● You can also upgrade your packages – Always do an update first to make sure you have the latest information – Then apt-get -u upgrade – The “-u” switch causes the command to display a list of all of the packages that will be upgraded. You wouldn't do this blind! Washtenaw Linux Users Group 37
  38. 38. APT and Upgrades ● If you run this upgrade, sometimes it will tell you that some packages were not upgraded, that the upgrades were “held back”. This can be due to breaking a dependency, or because of a new dependency ● For new dependencies, you can install the needed packages ● You can also use APT to find out which packages have upgrades available: apt-show-versions -u Washtenaw Linux Users Group 38
  39. 39. Distribution Upgrades ● If you have a completely new distribution version (common with Ubuntu, for instance, which releases new versions every 6 months) apt-get -u dist-upgrade Washtenaw Linux Users Group 39
  40. 40. APT resources ● Washtenaw Linux Users Group 40
  41. 41. The Lowest Level ● Recall that there are three levels in package management ● Our first presentation focused on GUI front ends ● This presentation has so far focused on the middle level, using the command line ● There is also the lowest level Washtenaw Linux Users Group 41
  42. 42. Package Tool Levels GUI Package Tool High-Level Package Tool Low-Level Package Tool Washtenaw Linux Users Group 42
  43. 43. RPM and DPKG ● For our two package management systems, the lowest levels are RPM (Red Hat Package Manager) and DPKG (Debian package) ● These are most often used when there is a package available, but it is not in a repository ● For example, a web site may offer a package with an extension *.rpm or *.deb Washtenaw Linux Users Group 43
  44. 44. RPM Install 1 ● For example, suppose you needed to install Cinelarra for a 64-bit system, and you don't have it in a repository ● But you find this: cinelerra-2.1- 0.15.20081102.fc9.x86_64.rpm ● This is an RPM package, which you can install rpm -i cinelerra-2.1- 0.15.20081102.fc9.x86_64.rpm Washtenaw Linux Users Group 44
  45. 45. RPM Install 2 ● This command invokes RPM, tells it to install (-i), and gives it the name of the package to install ● This is still package management. RPM is doing a bunch of things as part of the installation process – Performing dependency checks. – Checking for conflicts. – Performing any tasks required before the install. – Deciding what to do with config files. Washtenaw Linux Users Group 45
  46. 46. RPM Install 3 – Unpacking files from the package and putting them in the proper place. – Performing any tasks required after the install. – Keeping track of what it did. (i.e. updating the database) ● RPM can also perform an install over the Internet rpm -i bar-1.0-1.i386.rpm Washtenaw Linux Users Group 46
  47. 47. RPM Install 4 ● If you want to see some of the activity, add a “v” option to the command rpm -iv <package name> ● If you are the impatient kind who likes to see progress bars, add an “h” option rpm -ivh <package name> Washtenaw Linux Users Group 47
  48. 48. RPM Erase 1 ● In RPM, removing a package is called “erase” rpm -e <package name> ● Again, this is doing a lot more than simply deleting a couple of files – It checks the RPM database to make sure that no other packages depend on the package being erased. – It executes a pre-uninstall script (if one exists). – It checks to see if any of the package's config files have been modified. If so, it saves copies of them. Washtenaw Linux Users Group 48
  49. 49. RPM Erase 2 – It reviews the RPM database to find every file listed as being part of the package, and if they do not belong to another package, deletes them. – It executes a post-uninstall script (if one exists). – It removes all traces of the package (and the files belonging to it) from the RPM database. ● There is no “v” option for the erase command, but there is a variation called “vv” that gives you a lot of information rpm -evv <package name> Washtenaw Linux Users Group 49
  50. 50. RPM Upgrade ● There is an upgrade option as well rpm -U <package name> ● Note the capital “U” here ● Essentially, what this command does is a combination of install and erase. It installs the new version and erases the old version, all in one go. Washtenaw Linux Users Group 50
  51. 51. RPM Upgrade Remorse ● Suppose you upgraded a package you really love to the newest version ● You try to run it, and your screen goes blank rpm -Uv --oldpackage <package name> ● This is like “upgrading” to the older version ● Note: If you can boot to a command prompt you can do this Washtenaw Linux Users Group 51
  52. 52. DPKG 1 ● As with RPM, sometimes you can only find a *.deb file to install from ● The commands are pretty similar dpkg -i gedit-2.12.1.deb ● As with RPM, the DPKG package manager is doing a lot in the background – It is checking and resolving dependencies – It is installing any other packages needed – It is updating the database, etc. Washtenaw Linux Users Group 52
  53. 53. DPKG 2 ● In DPKG you remove a package if you don't want it any more dpkg -r gedit ● Another option lets you remove all of the configuration files as well dpkg -P gedit ● Upgrading a package uses the install command dpkg -i gedit-2.12.2.deb Washtenaw Linux Users Group 53
  54. 54. DPKG 3 ● One of my favorites is a command to use to help clean up a problem that has come up when I tried to use a more high-level package manager dpkg –configure -a ● If something goes wrong in the middle of an install, this cleans up the database Washtenaw Linux Users Group 54
  55. 55. Resources ● RPM – html – ● DPKG – apt-get-dpkg-primer-for-new.html – dpkg-cheat-sheet.php Washtenaw Linux Users Group 55
  56. 56. Final Thoughts ● The four package managers we covered in this presentation (YUM, RPM, APT, DPKG) all have a lot more capabilities than this one presentation could cover. Check the man pages for a full description of what they can do. ● One more time, remember that all of these commands are administrative commands, and you need to run them as root, or precede them with “sudo” Washtenaw Linux Users Group 56