Lesson 7: Packages, Software, Libraries

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Software

Everything that isn’t hardware.

• Code that is run on a Computer.
• Binaries.
• Scripts.
• Packages

Libraries

• Often used to make development easier.
• Rarely run on it’s own.
• Shared code.
• Binaries are linked dynamically to libraries (kind of like DLL’s in Windows)

$ ldd /usr/bin/nano
  linux-vdso.so.1 =>  (0x00007ffc1fdcd000)
  libncursesw.so.5 => /lib64/libncursesw.so.5 (0x00007ff2cfaee000)
  libtinfo.so.5 => /lib64/libtinfo.so.5 (0x00007ff2cf8c4000)
  libc.so.6 => /lib64/libc.so.6 (0x00007ff2cf500000)
  libdl.so.2 => /lib64/libdl.so.2 (0x00007ff2cf2fc000)
  /lib64/ld-linux-x86-64.so.2 (0x000055e46c4b4000)

Package Management

• Automagically manage software and libraries on your system.
• Examples:
  • Android Play Store
  • Apple App store
  • Steam
  • apt (Debian/Ubuntu)
  • yum (CentOS/Fedora/RHEL)

Package Management

Take care of installation and removal of software

Popular Linux System Package Managers

.rpm

• yum - RPM Package manager with repo support
• rpm - low level package manager tool used by yum
• Used by RedHat, CentOS, Fedora and others

.deb

• apt - Debian package manager with repo support
• dpkg - low level package manager tool used by apt
• Used by Debian, Ubuntu, Linux Mint and others

Yum vs. Apt

Yum

• XML repository format
• Automatic metadata syncing
• Supports a plugin module system to make it extensible
• Checks all dependencies before downloading

Apt

• Upgrade and Dist-Upgrade
  • Dist-Upgrade applies intelligent upgrading decisions during a major system upgrade
• Can completely remove all files including config files

Programming Language Package Managers

Examples:

• Python: pip
• Ruby: gem, rubygems
• Haskell: cabal
• NodeJS: npm
• ... and so on forever ...

Other Package Managers

Portage

The Source-based package manager for Gentoo.

Pacman

The Simple Arch Linux Package manager.

Nix

A ‘Fully Functional/Transactional’ package manager.

Brew

An Open Source package manager for OSX.

Chocolatey

A package manager for Windows.

Installation from Source

How to install a package from source:

Exercise: Install sl

1. Install the git, gcc, make and ncurses-devel packages via package manager.
2. Clone https://github.com/mtoyoda/sl.git using git
3. Build the software using make
4. Copy the compiled sl binary into the directory ~/local/bin/.
5. Update your $PATH to include $HOME/local/bin
6. Run ‘whereis sl‘ to ensure it’s in your path
7. Run sl and see what happens!

Answer: Install sl

$ sudo yum install git gcc make ncurses-devel
$ git clone https://github.com/mtoyoda/sl.git
$ cd sl
$ make
gcc -O -o sl sl.c -lncurses
$ mkdir -p ~/local/bin
$ cp sl ~/local/bin/
$ echo "export PATH=$HOME/local/bin:$PATH" >> ~/.bashrc
$ source ~/.bashrc
$ whereis sl
sl: /home/dobc/local/bin/sl
$ sl

Exercise: Install grep

1. Check the current version of grep
2. Double check it’s location using which
3. Download the latest tarball: http://mirrors.kernel.org/gnu/grep/grep-3.1.tar.xz
4. Unpack using tar
5. cd into the unpacked folder
6. Run ‘./configure --prefix=$HOME/local/‘, ‘make‘ and then ‘make install‘
7. Run ‘hash -r‘ to ensure your environment knows about the new binary
8. Check the current version of grep (it should be 3.1 now!)
9. Double check it’s location using which

Answer: Install grep

$ grep --version
grep (GNU grep) 2.20
$ which grep
alias grep='grep --color=auto'
        /usr/bin/grep
$ wget http://mirrors.kernel.org/gnu/grep/grep-3.1.tar.xz
$ tar -Jxvf grep-3.1.tar.xz
$ cd grep-3.1
$ ./configure --prefix=$HOME/local/
$ make
$ make install
$ hash -r
$ grep --version
grep (GNU grep) 3.1
$ which grep
alias grep='grep --color=auto'
        ~/local/bin/grep

Further Reading