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:
Specific commands for each system vary, but at their core they all provide the same functionality:
In the following examples, we will be using the package dstat. 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:
bash-4.0$ yum search dstat
======================== N/S Matched: dstat =========================
dstat.noarch : Versatile resource statistics tool
You can install a package using yum, by running:
bash-4.0$ 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:
bash-4.0$ rpm -i dstat-0.7.0-1.el6.noarch.rpm
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:
bash-4.0$ yum install dstat
To upgrade all packages that have newer versions available, run:
bash-4.0$ yum upgrade
To upgrade a package with an RPM file, run:
bash-4.0$ rpm -Uvh dstat-0.7.1-1.el6.noarch.rpm
To uninstall a package using yum, run:
bash-4.0$ yum remove dstat
Similarly, you can uninstall a package with rpm:
bash-4.0$ rpm -e dstat
You can clean the RPM database, forcing it to refresh package metadata from its sources on next install or upgrade operation.
bash-4.0$ yum clean all
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:
bash-4.0$ 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:
bash-4.0$ 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:
bash-4.0$ rpm -qf /usr/bin/dstat
dstat-0.7.0-1.el6.noarch
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.
In the following examples, we will be using the package dstat in our examples. 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:
bash-4.0$ apt-cache search dstat
dstat - versatile resource statistics tool
You can install a package through apt, by running:
bash-4.0# 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:
bash-4.0# dpkg -i dstat_0.7.2-3_all.deb
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.
To upgrade using apt, when a newer package is available, simply ask apt to install it again:
bash-4.0# apt-get install dstat
To upgrade a package with an deb file, run:
bash-4.0# dpkg -i dstat_0.7.2-3_all.deb
To uninstall a package using apt, run:
bash-4.0# apt-get remove dstat
Similarly, you can uninstall a package with dpkg:
bash-4.0# 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:
bash-4.0# apt-get purge dstat
or:
bash-4.0# apt-get --purge remove dstat
or:
bash-4.0# dpkg -P dstat
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:
bash-4.0$ 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:
bash-4.0$ 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:
bash-4.0$ dpkg-query -S /usr/bin/dstat
dstat: /usr/bin/dstat