{"id":10831,"date":"2024-12-14T06:46:42","date_gmt":"2024-12-14T06:46:42","guid":{"rendered":"https:\/\/blog.trustedhosting.in\/?p=10831"},"modified":"2024-12-14T06:46:42","modified_gmt":"2024-12-14T06:46:42","slug":"package-management-functions-in-linux","status":"publish","type":"post","link":"https:\/\/www.webystrata.com\/blog\/package-management-functions-in-linux\/","title":{"rendered":"Package Management Functions in Linux"},"content":{"rendered":"
\"<\/a>
\u00a0<\/figcaption><\/figure>\n

\u00a0Package Management Functions in Linux<\/h1>\n

As most UKFast servers<\/a> are either CentOS\/Red Hat or Ubuntu\/Debian, this article will only cover two of the most popular Linux package managers,\u00a0yum<\/span><\/code>\u00a0and\u00a0apt<\/span><\/code>.<\/p>\n

\n

yum<\/h2>\n
\n

Installing Packages<\/h3>\n

To install a package in yum, the following syntax can be used:<\/p>\n

\n
\n
   yum install $PACKAGE_NAME<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
This will search the currently installed repositories for a package with that name and install it if it\u2019s found.<\/p>\n
If the package you\u2019re looking for isn\u2019t found, then you may have to install an additional repository that does provide it.<\/p>\n
A common additional repository is\u00a0epel<\/span><\/code>\u00a0(Extra Packages for Enterprise Linux).<\/p>\n
On CentOS, this can itself be installed using yum:<\/p>\n
\n
\n
   yum install epel-release<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
If you\u2019re using official Red Hat Enterprise Linux, you will need to download the RPM from the EPEL site and install it manually, as well as enabling packages in the \u2018optional\u2019 RHEL repo. More instructions can be found\u00a0here<\/p>\n
With this installed, we can then install additional utilities on our server that were previously unavailable:<\/p>\n
\n
\n
   yum install htop<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n<\/section>\n
\n
Updating Packages<\/h3>\n
\n
In all these examples, the update command will be used rather than upgrade. Both commands look to perform the same function, but upgrade will remove packages that it classifies as obsolete as part of the upgrade process. If you\u2019re confident in what you\u2019re removing or drive space is at a premium then this option can be used instead.<\/p>\n<\/div>\n
The update syntax for yum is similar to the install syntax:<\/p>\n
\n
\n
   yum update $PACKAGE_NAME<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
If it\u2019s just one package that needs to be updated then the above syntax is fine, for example:<\/p>\n
\n
\n
   yum update httpd<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
If you\u2019re looking to update all the packages on your server<\/a>, simply run the command without a package name:<\/p>\n
\n
\n
   yum update<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
\n
Take care when updating all the packages on a server, this isn\u2019t something that should be done blindly. Review the packages that are going to update before accepting it. Failure to review package updates could result in you running a higher version of something critical (such as PHP) than your code supports.<\/p>\n<\/div>\n<\/section>\n
\n
Extra functions<\/h3>\n
You can always run a number of checks with yum before either installing or updating an application.<\/p>\n
If you wish to check whether a package is available on your system, you can always run a search in yum. This will print out all the packages that match your search:<\/p>\n
\n
\n
   yum search $QUERY<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
An example of this, including a snippet of the output, is as follows:<\/p>\n
\n
\n
   yum search php<\/span>\r\n\r\n   ...<\/span>\r\n   =============================== N\/S matched: php ===============================<\/span>\r\n   php.x86_64 : PHP scripting language for creating dynamic web sites<\/span>\r\n   php-Assetic.noarch : Asset Management for PHP<\/span>\r\n   php-EasyRdf.noarch : A PHP library designed to make it easy to consume and<\/span>\r\n                      : produce RDF<\/span>\r\n   ...<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
If the package exists on your system, you can pull additional information on it, including what version of the package is available to you.<\/p>\n
\n
This will also show you information on an updated version of the package you\u2019ve got. It also highlights the package\u2019s name in a different collour based on its status.<\/p>\n
Red: Obsolete yellow: Installed from another source bold white: Currently installed white: Available, but not installed blue: Update<\/p>\n<\/div>\n
\n
\n
   yum info $PACKAGE_NAME<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
Here is an example, including a snippet of the output, without colour highlights:<\/p>\n
\n
\n
   yum info php70w<\/span>\r\n\r\n   ...<\/span>\r\n   Installed Packages<\/span>\r\n   Name        : **php70w**<\/span>\r\n   Arch        : x86_64<\/span>\r\n   Version     : 7.0.11<\/span>\r\n   Release     : 1.w7<\/span>\r\n   Size        : 9.0 M<\/span>\r\n   Repo        : installed<\/span>\r\n   From repo   : webtatic<\/span>\r\n   ...<\/span>\r\n   Available Packages<\/span>\r\n   Name        : **php70w**<\/span>\r\n   Arch        : x86_64<\/span>\r\n   Version     : 7.0.12<\/span>\r\n   Release     : 1.w7<\/span>\r\n   Size        : 2.8 M<\/span>\r\n   Repo        : webtatic\/x86_64<\/span>\r\n   ...<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
Yum also has great history features that allow you to examine your previous installations and roll them back if necessary.<\/p>\n
To view the history of your yum transactions, run\u00a0yum<\/span>\u00a0history<\/span>\u00a0list<\/span><\/code>, which will output something like:<\/p>\n
\n
\n
[root@7dd0ac475f64 \/]# <\/span>yum history<\/span>\r\nLoaded plugins: fastestmirror, ovl<\/span>\r\nID     | Command line             | Date and time    | Action(s)      | Altered<\/span>\r\n-------------------------------------------------------------------------------<\/span>\r\n     4 | groupinstall development | 2017-10-24 09:20 | I, U           |  109 EE<\/span>\r\n     3 | install vim-enhanced     | 2017-10-24 09:19 | Install        |   33 EE<\/span>\r\n     2 | -y remove bind-libs bind | 2017-08-01 17:24 | Erase          |   35 E<<\/span>\r\n     1 |                          | 2017-08-01 17:23 | Install        |  178 ><\/span>\r\nhistory list<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
In the above example, if you had finished with the packaged you installed in transaction 4, you could then remove those by running\u00a0yum<\/span>\u00a0history<\/span>\u00a0undo<\/span>\u00a04<\/span><\/code>. If you wished to rollback your server to transaction 2, you could run\u00a0yum<\/span>\u00a0history<\/span>\u00a0rollback<\/span>\u00a02<\/span><\/code>\u00a0which would remove packages installed in transactions 3 and 4.<\/p>\n
You can get more information about this powerful feature by running\u00a0yum<\/span>\u00a0help<\/span>\u00a0history<\/span><\/code>\u00a0or viewing the yum man page (man<\/span>\u00a0yum<\/span><\/code>).<\/p>\n<\/section>\n<\/section>\n
\n
apt<\/h2>\n
\n
Installing Packages<\/h3>\n
To install a package with\u00a0apt<\/span><\/code>\u00a0you should first update the apt cache, then install your desired package:<\/p>\n
\n
\n
   apt-get update<\/span>\r\n   apt-get install $PACKAGE_NAME<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
Updating the cache first is important as this will ensure you get the latest available packages and security updates.<\/p>\n<\/section>\n
\n
Updating Packages<\/h3>\n
As with installing, you should ensure your apt cache is up to date so you get the latest software updates and security patches.<\/p>\n
\n
\n
   apt-get update<\/span>\r\n   apt-get upgrade<\/span>\r\n   or<\/span>\r\n   aptitude update<\/span>\r\n   aptitude upgrade<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
This will pull in all available updates for your system. Sometimes you may find that packages have been held back (usually Linux kernel updates). These can be pulled in by running a\u00a0dist-upgrade<\/span><\/code>.<\/p>\n
\n
\n
   apt-get dist-upgrade<\/span>\r\n   or<\/span>\r\n   aptitude full-upgrade<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
If you wish to view which version you\u2019re upgrading to and from you can always enable verbosity with the \u2018-V\u2019 option<\/p>\n
\n
\n
   apt-get -V upgrade|dist-upgrade<\/span>\r\n   or<\/span>\r\n   aptitude -V upgrade|full-upgrade<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
\n
Take care when updating all packages on a server. This is not something which should be done blindly. Review the packages that are going be updated before accepting the upgrade. If you fail to review the packages you may end up installing a new major version of a package which is not going to be compatible with your code, e.g. MySQL or PHP.<\/p>\n<\/div>\n<\/section>\n
\n
Extra Functions<\/h3>\n
With apt, there are 2 ways to perform a search for packages, but viewing package info applies the same to both methods.<\/p>\n
\n
\n
   apt-cache search $QUERY<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
This will display all packages that have matches based on name, summary, and full description.<\/p>\n
If you only want package and summary searches, you can run the following:<\/p>\n
\n
\n
   aptitude search $QUERY<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
Here are some examples and their outputs:<\/p>\n
\n
\n
   apt-cache search php<\/span>\r\n\r\n   ...<\/span>\r\n   adminer - Web-based database administration tool<\/span>\r\n   air-quality-sensor - user space driver for AppliedSensor's Indoor Air Monitor<\/span>\r\n   ampache - web-based audio file management system<\/span>\r\n   ampache-common - web-based audio file management system common files<\/span>\r\n   ampache-themes - Themes for Ampache<\/span>\r\n   aolserver4-doc - AOL web server version 4 - documentation<\/span>\r\n   ...<\/span>\r\n\r\n   aptitude search php<\/span>\r\n\r\n   ...<\/span>\r\n   p   cakephp               - MVC rapid application development framework for PHP<\/span>\r\n   p   cakephp-instaweb      - Development webserver for CakePHP applications<\/span>\r\n   p   cakephp-scripts       - MVC rapid application development framework for PHP (scripts)<\/span>\r\n   p   dh-make-php           - Creates Debian source packages for PHP PEAR and PECL extensions<\/span>\r\n   p   dh-php5               - debhelper add-on to handle PHP PECL extensions<\/span>\r\n   ...<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
With aptitude searches, they show information about the installation status of a package.<\/p>\n
    \n
  • \u2018p\u2019 shows that the package is available, but not installed.<\/li>\n
  • \u2018v\u2019 shows that this is a virtual package, i.e. it\u2019s provided by another package.<\/li>\n
  • \u2018i\u2019 shows that the package is installed.<\/li>\n
  • \u2018c\u2019 shows that the package was removed, but the configuration still remains<\/li>\n<\/ul>\n
    If an \u2018A\u2019 is visible, it shows that this was automatically installed as a dependency to another package.<\/p>\n
    After searching for a package you can get more information with the following command:<\/p>\n
    \n
    \n
       apt-cache show $PACKAGE_NAME<\/span>\r\n   or<\/span>\r\n   aptitude show $PACKAGE_NAME<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
    Here is an example, and a snippet of the output:<\/p>\n
    \n
    \n
       apt-cache show linux-image-amd64<\/span>\r\n   or<\/span>\r\n   aptitude show linux-image-amd64<\/span>\r\n\r\n   ...<\/span>\r\n   Package: linux-image-amd64<\/span>\r\n   State: installed<\/span>\r\n   Automatically installed: no<\/span>\r\n   Version: 3.16+63<\/span>\r\n   Priority: optional<\/span>\r\n   Section: kernel<\/span>\r\n   ...<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
    This will tell you additional information, such as what packages it depends on, and which packages it will conflict with, along with a description of what the package does.<\/p>\n<\/section>\n<\/section>\n","protected":false},"excerpt":{"rendered":"
    \u00a0Package Management Functions in Linux As most UKFast servers are either CentOS\/Red Hat or Ubuntu\/Debian, this article will only cover…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-10831","post","type-post","status-publish","format-standard","hentry","category-linux"],"_links":{"self":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts\/10831","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/comments?post=10831"}],"version-history":[{"count":2,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts\/10831\/revisions"}],"predecessor-version":[{"id":10834,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts\/10831\/revisions\/10834"}],"wp:attachment":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/media?parent=10831"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/categories?post=10831"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/tags?post=10831"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}