Package management ****************** Workflow ======== What is a package manager? ========================== Modern operating systems use package managers to take care of the installation, maintenance and removal of software. On Windows this is `Windows Installer `_ (formerly Microsoft Installer). On Linux there are two popular package managers: * APT (used by Debian, Ubuntu) * RPM (RedHat, CentOS, Fedora, SuSe) Specific commands for each system vary, but at their core they all provide the same functionality: * Install and uninstall packages * Upgrade packages * Install packages from a central repository * Search for information on installed packages and files RPM and yum (RedHat, CentOS, Fedora, Scientific Linux) ====================================================== In the following examples, we will be using ``dstat`` as the package we will be manipulating. The process however applies to any software you may want to install. Yum provides a wrapper around RPM, which can be used to search for, and install packages from multiple package repositories. It also resolves dependencies, so that if a package has prerequisites, they will be installed at the same time. If your Linux distribution uses RPM and yum, you can search for packages by running: .. code-block:: console user@opsschool ~$ yum search dstat ======================== N/S Matched: dstat ========================= dstat.noarch : Versatile resource statistics tool Installing packages ------------------- You can install a package using yum, by running: .. code-block:: console root@opsschool ~# yum install dstat ============================================================================= Package Arch Version Repository Size ============================================================================= Installing: dstat noarch 0.7.0-1.el6 CentOS-6 144 k Transaction Summary ============================================================================= Install 1 Package(s) Total download size: 144 k Installed size: 660 k Is this ok [y/N]: If you have a downloaded RPM file, you can also install the package directly with the ``rpm`` command: .. code-block:: console root@opsschool ~# rpm -i dstat-0.7.0-1.el6.noarch.rpm Upgrading packages ------------------ RPM and yum both make it easy to upgrade existing packages, too. Over time, new packages may be added to the yum repositories that are configured on your system, or you may have a newer RPM for an already installed package. To upgrade a package using yum, when a newer package is available, simply ask yum to install it again: .. code-block:: console root@opsschool ~# yum install dstat To upgrade all packages that have newer versions available, run: .. code-block:: console root@opsschool ~# yum upgrade To upgrade a package with an RPM file, run: .. code-block:: console root@opsschool ~# rpm -Uvh dstat-0.7.1-1.el6.noarch.rpm Uninstalling packages --------------------- To uninstall a package using yum, run: .. code-block:: console root@opsschool ~# yum remove dstat Similarly, you can uninstall a package with rpm: .. code-block:: console root@opsschool ~# rpm -e dstat Cleaning the RPM database ------------------------- You can clean the RPM database, forcing it to refresh package metadata from its sources on next install or upgrade operation. .. code-block:: console root@opsschool ~# yum clean all Querying the RPM database ------------------------- Occasionally you will want to find out specific information regarding installed packages. The ``-q`` option to the ``rpm`` command comes in handy here. Let's take a look at a few examples: One common task is to see if you have a package installed. The ``-qa`` option by itself will list ALL installed packages. You can also ask it to list specific packages if they are installed: .. code-block:: console user@opsschool ~$ rpm -qa dstat dstat-0.7.0-1.el6.noarch Now let's say we want to list all of the files installed by a package. The ``-ql`` option is the one to use: .. code-block:: console user@opsschool ~$ rpm -ql dstat /usr/bin/dstat /usr/share/doc/dstat-0.7.0 /usr/share/doc/dstat-0.7.0/AUTHORS /usr/share/doc/dstat-0.7.0/COPYING /usr/share/doc/dstat-0.7.0/ChangeLog ... We can also do the reverse of the previous operation. If we have a file, and want to known which package it belongs to: .. code-block:: console user@opsschool ~$ rpm -qf /usr/bin/dstat dstat-0.7.0-1.el6.noarch Creating packages ----------------- .. todo:: Mention spec files and roughly how RPMs are put together. .. todo:: Then introduce FPM and tell them not to bother with spec files yet. There are two todos here. dpkg and APT (Debian, Ubuntu) ============================= In the following examples, we will be using ``dstat`` as the package we will be manipulating. The process however applies to any software you may want to install. APT provides a wrapper around ``dpkg``, which can be used to search for, and install packages from multiple package repositories. If your Linux distribution uses ``dpkg`` and APT, you can search for packages by running: .. code-block:: console user@opsschool ~$ apt-cache search dstat dstat - versatile resource statistics tool .. note:: In the following sections, we will be describing use of APT through the traditional commands of ``apt-get`` and ``apt-cache``. However, modern systems may ship with an additional command ``apt`` which (generally) combines the functionality of both of the above commands. If your system supports ``apt`` by itself, it is recommended to use that, as it is a bit more user friendly. Installing packages ------------------- You can install a package through apt, by running: .. code-block:: console root@opsschool ~# apt-get install dstat The following NEW packages will be installed: dstat 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/79.3 kB of archives. After this operation, 351 kB of additional disk space will be used. Selecting previously unselected package dstat. (Reading database ... 124189 files and directories currently installed.) Unpacking dstat (from .../archives/dstat_0.7.2-3_all.deb) ... Processing triggers for man-db ... Setting up dstat (0.7.2-3) ... If you have a downloaded DEB file, you can also install the package directly with the ``dpkg`` command: .. code-block:: console root@opsschool ~# dpkg -i dstat_0.7.2-3_all.deb Upgrading packages ------------------ dpkg and APT both make it easy to upgrade existing packages, too. Over time, new packages may be added to the apt repositories that are configured on your system, or you may have a newer deb for an already installed package. In order to retrieve the updated package lists, first run: .. code-block:: console root@opsschool ~# apt-get update To upgrade a single package using apt, when a newer package is available, simply ask apt to install it again: .. code-block:: console root@opsschool ~# apt-get install dstat To upgrade all packages at once, run: .. code-block:: console root@opsschool ~# apt-get upgrade To upgrade a package with an deb file, run: .. code-block:: console root@opsschool ~# dpkg -i dstat_0.7.2-3_all.deb Uninstalling packages --------------------- To uninstall a package using apt, run: .. code-block:: console root@opsschool ~# apt-get remove dstat Similarly, you can uninstall a package with dpkg: .. code-block:: console root@opsschool ~# dpkg -r dstat With APT and dpkg, removing a package still leaves behind any configuration files, in case you wish to reinstall the package again later. To fully delete packages and their configuration files, you need to ``purge``: .. code-block:: console root@opsschool ~# apt-get purge dstat or: .. code-block:: console root@opsschool ~# apt-get --purge remove dstat or: .. code-block:: console root@opsschool ~# dpkg -P dstat Querying the dpkg database -------------------------- Occasionally you will want to find out specific information regarding installed packages. The ``dpkg-query`` command has many options to help. Let's take a look at a few examples: One common task is to see if you have a package installed. The ``-l`` option by itself will list ALL installed packages. You can also ask it to list specific packages if they are installed: .. code-block:: console user@opsschool ~$ dpkg-query -l dstat Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name Version Architecture Description +++-==============-============-============-================================== ii dstat 0.7.2-3 all versatile resource statistics tool Now let's say we want to list all of the files installed by a package. The ``-L`` option is the one to use: .. code-block:: console user@opsschool ~$ dpkg-query -L dstat /. /usr /usr/bin /usr/bin/dstat /usr/share ... We can also do the reverse of the previous operation. If we have a file, and want to know to which package it belongs: .. code-block:: console user@opsschool ~$ dpkg-query -S /usr/bin/dstat dstat: /usr/bin/dstat