A quick summary of Linux package managers | Linux Tutorial for
Beginners (4:59)
Code Examples and Video Script
Welcome. Today's question: How do you install software in Linux?
I'm Paul, and for those of us coming from Windows and Mac, when faced
with the command prompt, it's easy to feel uncertain.
So here, I'll simplify the installation process, starting with two
forks of Linux distributions.
And because we have high aspirations here, we'll go beyond just
installing software, and have a more holistic, yet brief, discussion
about package management, a very complex subject.
I'll show you where to find help, and I'll also define terms and we'll
practice a bit (with the commands below) before heading on to user
permissions.
apt-cache
apt-get
dpkg
whatis
less
which
wc
Step 1 - Package Managers for Debian and Fedora
Let's jump to the Linux command line on a local test server sitting in
my office here in California. As I usually do, I'll use
whatis to define the programs used,
so pause if you want to check that out.
paul@fullstack:~$ whatis apt-cache apt-get dpkg whatis less wc
apt-cache (8) - query the APT cache
apt-get (8) - APT package handling utility - - command-line interface
dpkg (1) - package manager for Debian
whatis (1) - display one-line manual page descriptions
less (1) - opposite of more
wc (1) - print newline, word, and byte counts for each file
paul@fullstack:~$ less notes/video0018.txt
Next, I'll open a text file using less
to outline this discussion.
Package Management (video 18)
Two forks
Debian-style: Debian, Ubuntu, Mint > dpkg, apt and aptitude
Fedora-style: Fedora, Red Hat, CentOS > rpm, yum
Terms
repositories - /etc/apt/sources.list
package name - simple name like python3 or nano
package file - a file in .deb or .rpm format
package maintainer - responsible for compatibility
dependencies - other required packages
Command line programs on Debian-style distributions
dpkg - for dowloaded files in .deb format
apt (apt-get apt-cache) - using package name format
aptitude - GUI-like interface
Syntax for apt
command -option(s) argument(s)
command -option(s) action argument(s)
$ sudo apt-get update
$ sudo apt-get upgrade
$ sudo apt-get install python3
notes/video0018.txt
Most popular Linux distributions fall in one of two camps, Debian-style
and Fedora-style.
Debian, Ubuntu and Mint use programs like
dpkg,
apt and
aptitude.
Fedora, Red Hat and CentOS use
rpm and
yum.
Step 2 - Package Management Programs We Use Here
In another window, I'll do a which on
all five, showing program locations, confirming that my distribution is
Debian-style.
paul@fullstack:~$ which apt aptitude dpkg rpm yum
/usr/bin/apt
/usr/bin/aptitude
/usr/bin/dpkg
And quickly we're using the command line in this Playlist, and if you
prefer a GUI, it will have its own package management system.
Step 3 - Finding Help and Defining Terms
Let's define terms.
Repositories
Repositories are Internet locations where software is hosted.
For example Debian
has 43,000 packages, and you can use the site's search functions, or
search by section to find packages.
The file /etc/apt/sources.list points
to sources where packages are found.
Package name
Next, package name is a simple name like
python3 or
nano.
Package file
The package file itself has
a .deb or .rpm extension.
Package maintainer
The package maintainer ensures the software works properly.
Dependencies
Dependencies are other packages required to install a package.
Package managers for Debian-style distributions
Let's summarize three programs with use cases.
The advanced dpkg installs downloaded
files in .deb format.
apt uses package names, instead of
package files, making it easier for beginners, meaning it downloads
files from repositories, installs packages, modifies configuration
files and resolves dependencies automatically.
Last, aptitude offers a GUI-like
interface.
Syntax for apt
I need to mention the apt syntax is
a bit different.
command -option(s) argument(s)
command -option(s) action argument(s)
Our normal convention for commands goes like this,
command -option(s) argument(s) but
apt-cache and
apt-get have
actions.
Let's explore that, showing you commands every beginner should know.
Start with --help or use the
man page for help.
paul@fullstack:~$ apt-cache --help
apt 1.0.9.8.4 for amd64 compiled on Dec 11 2016 09:48:19
Usage: apt-cache [options] command
apt-cache [options] showpkg pkg1 [pkg2 ...]
apt-cache [options] showsrc pkg1 [pkg2 ...]
apt-cache is a low-level tool used to query information
from APT's binary cache files
Commands:
gencaches - Build both the package and source cache
showpkg - Show some general information for a single package
showsrc - Show source records
stats - Show some basic statistics
dump - Show the entire file in a terse form
dumpavail - Print an available file to stdout
unmet - Show unmet dependencies
search - Search the package list for a regex pattern
show - Show a readable record for the package
depends - Show raw dependency information for a package
rdepends - Show reverse dependency information for a package
pkgnames - List the names of all packages in the system
dotty - Generate package graphs for GraphViz
xvcg - Generate package graphs for xvcg
policy - Show policy settings
Options:
-h This help text.
-p=? The package cache.
-s=? The source cache.
-q Disable progress indicator.
-i Show only important deps for the unmet command.
-c=? Read this configuration file
-o=? Set an arbitrary configuration option, eg -o dir::cache=/tmp
See the apt-cache(8) and apt.conf(5) manual pages for more information.
paul@fullstack:~$
First, apt-cache has 15 actions to
query a local cache file downloaded during the last
apt-get update.
Let's use apt-cache to search the
cache for nano in the name field.
paul@fullstack:~$ apt-cache -n search nano
science-nanoscale-physics - Debian Science Nanoscale Physics packages
science-nanoscale-physics-dev - Debian Science Nanoscale Physics development packages
kiki-the-nano-bot - 3D puzzle game, mixing Sokoban and Kula-World
kiki-the-nano-bot-data - Kiki the nano bot - game data
libnanoxml2-java - small XML parser for Java
libnanoxml2-java-doc - documentation for libnanoxml2-java
nano - small, friendly text editor inspired by Pico
nano-tiny - small, friendly text editor inspired by Pico - tiny build
nanoblogger - Small weblog engine for the command line
nanoblogger-extra - Nanoblogger plugins
nanoc - static site generator written in Ruby
nanoc-doc - static site generator written in Ruby - documentation
libnanomsg-dev - nanomsg development files
libnanomsg0 - high-performance implementation of scalability libraries
libnanomsg0-dbg - high-performance implementation of scalability libraries - debug symbols
paul@fullstack:~$ clear
And apt-cache stats for a summary of
the cache.
paul@fullstack:~$ apt-cache -n search nano
Total package names: 54242 (1,085 k)
Total package structures: 54255 (3,038 k)
Normal packages: 41905
Pure virtual packages: 392
Single virtual packages: 4725
Mixed virtual packages: 450
Missing: 6783
Total distinct versions: 43562 (3,136 k)
Total distinct descriptions: 84892 (2,037 k)
Total dependencies: 269895 (7,557 k)
Total ver/file relations: 45114 (1,083 k)
Total Desc/File relations: 84892 (2,037 k)
Total Provides mappings: 7622 (152 k)
Total globbed strings: 75 (568 )
Total dependency version space: 1,102 k
Total slack space: 36.6 k
Total space accounted for: 15.0 M
paul@fullstack:~$ clear
Find help on the command apt-get
Next, apt-get has 15 actions, the most
important being: update,
upgrade and
install.
paul@fullstack:~$ apt-get --help
apt 1.0.9.8.4 for amd64 compiled on Dec 11 2016 09:48:19
Usage: apt-get [options] command
apt-get [options] install|remove pkg1 [pkg2 ...]
apt-get [options] source pkg1 [pkg2 ...]
apt-get is a simple command line interface for downloading and
installing packages. The most frequently used commands are update
and install.
Commands:
update - Retrieve new lists of packages
upgrade - Perform an upgrade
install - Install new packages (pkg is libc6 not libc6.deb)
remove - Remove packages
autoremove - Remove automatically all unused packages
purge - Remove packages and config files
source - Download source archives
build-dep - Configure build-dependencies for source packages
dist-upgrade - Distribution upgrade, see apt-get(8)
dselect-upgrade - Follow dselect selections
clean - Erase downloaded archive files
autoclean - Erase old downloaded archive files
check - Verify that there are no broken dependencies
changelog - Download and display the changelog for the given package
download - Download the binary package into the current directory
Options:
-h This help text.
-q Loggable output - no progress indicator
-qq No output except for errors
-d Download only - do NOT install or unpack archives
-s No-act. Perform ordering simulation
-y Assume Yes to all queries and do not prompt
-f Attempt to correct a system with broken dependencies in place
-m Attempt to continue if archives are unlocatable
-u Show a list of upgraded packages as well
-b Build the source package after fetching it
-V Show verbose version numbers
-c=? Read this configuration file
-o=? Set an arbitrary configuration option, eg -o dir::cache=/tmp
See the apt-get(8), sources.list(5) and apt.conf(5) manual
pages for more information and options.
This APT has Super Cow Powers.
Step 4 - Practice With apt-get update and dpkg
Update the local package cache with apt-get update
Let's kick off an apt-get update that
accesses the sources.list file, I
mentioned, and finds the download location then updates that local cache
with the latest from Debian.
paul@fullstack:~$ sudo apt-get update
Hit http://security.debian.org jessie/updates InRelease
Ign http://ftp.us.debian.org jessie InRelease
Hit http://ftp.us.debian.org jessie-updates InRelease
Hit http://security.debian.org jessie/updates/main Sources
Hit http://ftp.us.debian.org jessie Release.gpg
Hit http://security.debian.org jessie/updates/main amd64 Packages
Hit http://security.debian.org jessie-updates/main Translation-en
Hit http://ftp.us.debian.org jessie-updates/main Sources
Get:1 http://ftp.us.debian.org jessie-updates/main amd64 Packages/DiffIndex [6,916 B]
Get:2 http://ftp.us.debian.org jessie-updates/main Translation-en/DiffIndex [2,704 B]
Hit http://ftp.us.debian.org jessie Release
Hit http://ftp.us.debian.org jessie/main Sources
Hit http://ftp.us.debian.org jessie/main Translation-en
Fetched 9,620 B in 2s (4,524 B/s)
Reading package lists... Done
paul@fullstack:~$
Always do an apt-get update before an
apt-get upgrade or
apt-get install.
Here is how you would upgrade all of your installed packages as a
superuser (using sudo).
Update the local package cache with apt-get update
Are you curious about what's installed on your system?
We can use dpkg and do a count.
paul@fullstack:~$ dpkg -l | wc -l
489
To see the status of the package less,
use dpkg -s, offering status,
maintainer, version and dependencies.
paul@fullstack:~$ dpkg -s less
Package: less
Status: install ok installed
Priority: important
Section: text
Installed-Size: 253
Maintainer: Anibal Monsalve Salazar
Architecture: amd64
Multi-Arch: foreign
Version: 458-3
Depends: libc6 (>= 2.14), libtinfo5, debianutils (>= 1.8)
Description: pager program similar to more
This package provides "less", a file pager (that is, a memory-efficient
utility for displaying text one screenful at a time). Less has many
more features than the basic pager "more". As part of the GNU project,
it is widely regarded as the standard pager on UNIX-derived systems.
.
Also provided are "lessecho", a simple utility for ensuring arguments
with spaces are correctly quoted; "lesskey", a tool for modifying the
standard (vi-like) keybindings; and "lesspipe", a filter for specific
types of input, such as .doc or .txt.gz files.
Homepage: http://www.greenwoodsoftware.com/less/
paul@fullstack:~$
In future Intermediate videos, we'll answer:
What if something goes wrong?
How do you safely uninstall packages?
How do you install downloaded files?
Should you automate updates?
Step 5 - Next: Install Software Packages
So I covered a lot here, just so you've seen it and shortly we'll close
out this project on Linux For Beginners, then jump to the software
layer, install Python 3, cover the basics and get right to some math.
(Here is the beginning of our software stack)
Client : HTML, CSS, JavaScript
Software : Python Scientific Stack
Data : PostgreSQL, MySQL / MariaDB
OS : Linux (command line), Debian
Coming up next is user permissions.
Have a nice day.
What's Next?
Check out other free opportunities to learn on our YouTube Channel. And
follow @factorpad on Twitter and join our no-spam email list for updates.
To access all tutorials, click Outline.
To learn about Linux configuration files, click Back.
by