How to Manage Packages with APT on Ubuntu 18.04 LTS

APT also known as Advanced Packaging Tool is the command-line tool for managing packages in Debian-based distributions like Ubuntu 16.04, Ubuntu 18.04, Debian 8, Debian 9 and much more. APT simplifies the process of installing, removing, upgrading packages and even used to upgrade the entire operating system through the Command Line Interface

In this tutorial, we will explain how to manage packages using APT command line tool on Ubuntu 18.04 LTS server.

Requirements

  • A server running Ubuntu 18.04 LTS.
  • A root or sudo access on the server.

All commands below are run as root user. Either log in as root user on the shell or run:

sudo -s

to become the root user. As an alternative, you can prepend 'sudo ' to all commands.

Install and Update Packages

Apt-get works by obtaining information from different sources and stored in a local database. The update command fetched the packages from their locations and update the packages to a newer version.

apt-get update -y

After running the above command, your database should be up-to-date.

The upgrade command is used to upgrade all the currently installed software packages to the newer version.

apt-get upgrade -y

You can also use dist-upgrade command to upgrade the packages, but it changes package dependencies with a smart conflict resolution method.

apt-get dist-upgrade -y

Once your database is updated, you can install any packages by running the following command:

apt-get install package1 package2

For example, you can install Nginx web server package by running the following command:

apt-get install nginx

If you want to download only package file but not install it, you can run the following command:

apt-get install -d package1

The above command will download the package file in /var/cache/apt/archives directory.

To reinstall any package with the newer version run the following command:

apt-get install package1 --reinstall

Remove a Package with Apt

To remove a package from your system simply run the following command:

apt-get remove package1

The above command will only remove the package but keep the configuration file.

To remove the package with configuration file with the following command:

apt-get purge package1

You can also remove all unwanted packages and clean the database with the following command:

apt-get autoremove
apt-get clean

Search Package with Apt-Cache

The command apt-cache is used to search for software packages.

To find the package by its description, run the following command:

apt-cache search proftpd

You should see the following output:

resource-agents - Cluster Resource Agents
fail2ban - ban hosts that cause multiple authentication errors
ftpd - File Transfer Protocol (FTP) server
gadmin-proftpd - GTK+ configuration tool for proftpd
gadmin-proftpd-dbg - GTK+ configuration tool for proftpd debug package
gadmintools - GTK+ server administration tools (meta-package)
proftpd-basic - Versatile, virtual-hosting FTP daemon - binaries
proftpd-dev - Versatile, virtual-hosting FTP daemon - development files
proftpd-doc - Versatile, virtual-hosting FTP daemon - documentation
proftpd-mod-autohost - ProFTPD module mod_autohost
proftpd-mod-case - ProFTPD module mod_case
proftpd-mod-clamav - ProFTPD module mod_clamav
proftpd-mod-dnsbl - ProFTPD module mod_dnsbl
proftpd-mod-fsync - ProFTPD module mod_fsync
proftpd-mod-geoip - Versatile, virtual-hosting FTP daemon - GeoIP module
proftpd-mod-ldap - Versatile, virtual-hosting FTP daemon - LDAP module
proftpd-mod-msg - ProFTPD module mod_msg
proftpd-mod-mysql - Versatile, virtual-hosting FTP daemon - MySQL module
proftpd-mod-odbc - Versatile, virtual-hosting FTP daemon - ODBC module
proftpd-mod-pgsql - Versatile, virtual-hosting FTP daemon - PostgreSQL module
proftpd-mod-sqlite - Versatile, virtual-hosting FTP daemon - SQLite3 module
proftpd-mod-tar - ProFTPD module mod_tar
proftpd-mod-vroot - ProFTPD module mod_vroot

To find all the packages starting with proftpd with the following command:

apt-cache pkgnames proftpd

You should see the following output:

apt-cache pkgnames proftpd
proftpd-mod-dnsbl
proftpd-mod-odbc
proftpd-mod-pgsql
proftpd-doc
proftpd-mod-tar
proftpd-mod-ldap
proftpd-mod-case
proftpd-mod-geoip
proftpd-mod-mysql
proftpd-basic
proftpd-mod-vroot
proftpd-mod-clamav
proftpd-mod-autohost
proftpd-mod-fsync
proftpd-mod-sqlite
proftpd-mod-msg
proftpd-dev

You can check the complete information of any package (nano) with the following command:

apt-cache show nano

Output:

Package: nano
Priority: standard
Section: editors
Installed-Size: 600
Maintainer: Ubuntu Developers <[email protected]>
Original-Maintainer: Jordi Mallach <[email protected]>
Architecture: amd64
Version: 2.2.6-1ubuntu1
Replaces: pico
Provides: editor
Depends: libc6 (>= 2.14), libncursesw5 (>= 5.6+20070908), libtinfo5, dpkg (>= 1.15.4) | install-info
Suggests: spell
Conflicts: pico
Breaks: alpine-pico (<= 2.00+dfsg-5)
Filename: pool/main/n/nano/nano_2.2.6-1ubuntu1_amd64.deb
Size: 194060
MD5sum: c97dc062e9941bfe13b6b303cf8ed639
SHA1: ee93fcfd1f2ecd601b0a8f8932319848043f4f0f
SHA256: f20d8cca5c30b90ebf68301d126f86e473ac83e7d6fdc36f59bcd685c2eb4020
Description-en: small, friendly text editor inspired by Pico
 GNU nano is an easy-to-use text editor originally designed as a replacement
 for Pico, the ncurses-based editor from the non-free mailer package Pine
 (itself now available under the Apache License as Alpine).
 .
 However, nano also implements many features missing in pico, including:
  - feature toggles;
  - interactive search and replace (with regular expression support);
  - go to line (and column) command;
  - auto-indentation and color syntax-highlighting;
  - filename tab-completion and support for multiple buffers;
  - full internationalization support.
Description-md5: b7e1d8c3d831118724cfe8ea3996b595
Homepage: http://www.nano-editor.org/
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Origin: Ubuntu
Supported: 5y
Task: standard, kubuntu-active, kubuntu-active

To check the dependencies of a specific package with the following command:

apt-cache showpkg htop

Output:

Package: htop
Versions: 
2.1.0-3 (/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_bionic_main_binary-amd64_Packages) (/var/lib/dpkg/status)
 Description Language: 
                 File: /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_bionic_main_binary-amd64_Packages
                  MD5: 8eb5aa19b3c92a975dc78e2165f6688d
 Description Language: en
                 File: /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_bionic_main_i18n_Translation-en
                  MD5: 8eb5aa19b3c92a975dc78e2165f6688d


Reverse Depends: 
  ubuntu-server,htop
  lubuntu-qt-desktop,htop
  lubuntu-gtk-desktop,htop
  lubuntu-desktop,htop
  util-vserver,htop
  ubuntu-benchmark-tools,htop
  lubuntu-qt-desktop,htop
  lubuntu-gtk-desktop,htop
  lubuntu-desktop,htop
  hollywood,htop
  freedombox-setup,htop
Dependencies: 
2.1.0-3 - libc6 (2 2.15) libncursesw5 (2 6) libtinfo5 (2 6) lsof (0 (null)) strace (0 (null)) 
Provides: 
2.1.0-3 - 
Reverse Provides: 

To check whether a package is installed or not and which repository it belongs to with the following command:

apt-cache policy apache2

You should see the following output:

apache2:
  Installed: 2.4.29-1ubuntu4.5
  Candidate: 2.4.29-1ubuntu4.5
  Version table:
 *** 2.4.29-1ubuntu4.5 500
        500 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     2.4.29-1ubuntu4.4 500
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
     2.4.29-1ubuntu4 500
        500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages

APT Advanced Usage

You can also check for broken dependencies with the following command.

apt-get check

You should see the following output:

Reading package lists... Done
Building dependency tree       
Reading state information... Done

To search and install the build dependencies for a package (here vsftpd), use the following command:

apt-get build-dep vsftpd

You should see all the dependencies required by vsftpd package in the following output:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Note, selecting 'libcap-dev' instead of 'libcap2-dev'
The following NEW packages will be installed:
  debhelper dh-apparmor dh-apport libcap-dev libpam0g-dev po-debconf
The following packages will be upgraded:
  libpam0g
1 upgraded, 6 newly installed, 0 to remove and 595 not upgraded.
1 not fully installed or removed.
Need to get 1,020 kB of archives.
After this operation, 2,238 kB of additional disk space will be used.
Do you want to continue? [Y/n] 

To download the source code of any package, unpack and compile a package by running the following command:

apt-get --compile source htop

You should see the following output:

Reading package lists... Done
NOTICE: 'htop' packaging is maintained in the 'Git' version control system at:
https://salsa.debian.org/debian/htop.git
Please use:
git clone https://salsa.debian.org/debian/htop.git
to retrieve the latest (possibly unreleased) updates to the package.
Need to get 314 kB of source archives.
Get:1 http://archive.ubuntu.com/ubuntu bionic/main htop 2.1.0-3 (dsc) [1,961 B]
Get:2 http://archive.ubuntu.com/ubuntu bionic/main htop 2.1.0-3 (tar) [303 kB]                                                                        
Get:3 http://archive.ubuntu.com/ubuntu bionic/main htop 2.1.0-3 (diff) [8,824 B]                                                                      
Fetched 314 kB in 35s (8,877 B/s)                                                                                                                     
dpkg-source: info: extracting htop in htop-2.1.0
dpkg-source: info: unpacking htop_2.1.0.orig.tar.gz
dpkg-source: info: unpacking htop_2.1.0-3.debian.tar.xz
dpkg-source: info: applying 601-openvz-new-ctid-vpid.patch
dpkg-source: info: applying fix-small-terminals.patch
dpkg-source: info: applying fix-ldflags.patch
dpkg-source: info: applying fix-isalnum-crash.patch
dpkg-buildpackage: info: source package htop
dpkg-buildpackage: info: source version 2.1.0-3
dpkg-buildpackage: info: source distribution unstable
dpkg-buildpackage: info: source changed by Graham Inggs <[email protected]>
dpkg-buildpackage: info: host architecture amd64

To check the version of APT with the following command:

apt-get -v

Output:

apt 1.6.1 (amd64)
Supported modules:
*Ver: Standard .deb
*Pkg:  Debian dpkg interface (Priority 30)
 Pkg:  Debian APT solver interface (Priority -1000)
 Pkg:  Debian APT planner interface (Priority -1000)
 S.L: 'deb' Debian binary tree
 S.L: 'deb-src' Debian source tree
 Idx: Debian Source Index
 Idx: Debian Package Index
 Idx: Debian Translation Index
 Idx: Debian dpkg status file
 Idx: Debian deb file
 Idx: Debian dsc file
 Idx: Debian control file
 Idx: EDSP scenario file
 Idx: EIPP scenario file

You can list all the available options with APT by running the following command:

apt-get -h

Output:

apt 1.6.1 (amd64)
Usage: apt-get [options] command
       apt-get [options] install|remove pkg1 [pkg2 ...]
       apt-get [options] source pkg1 [pkg2 ...]

apt-get is a command line interface for retrieval of packages
and information about them from authenticated sources and
for installation, upgrade and removal of packages together
with their dependencies.

Most used commands:
  update - Retrieve new lists of packages
  upgrade - Perform an upgrade
  install - Install new packages (pkg is libc6 not libc6.deb)
  remove - Remove packages
  purge - Remove packages and config files
  autoremove - Remove automatically all unused packages
  dist-upgrade - Distribution upgrade, see apt-get(8)
  dselect-upgrade - Follow dselect selections
  build-dep - Configure build-dependencies for source packages
  clean - Erase downloaded archive files
  autoclean - Erase old downloaded archive files
  check - Verify that there are no broken dependencies
  source - Download source archives
  download - Download the binary package into the current directory
  changelog - Download and display the changelog for the given package

See apt-get(8) for more information about the available commands.
Configuration options and syntax is detailed in apt.conf(5).
Information about how to configure sources can be found in sources.list(5).
Package and version choices can be expressed via apt_preferences(5).
Security details are available in apt-secure(8).
                                        This APT has Super Cow Powers.
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