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Old 09-30-2009, 11:29 AM   #1
LQ Newbie
Registered: Sep 2009
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Using yum update *

So, I am not so new at most *nix things, however, I am overly cautious about running this command.

I ran it and it came back with 35 packages to install and 107 packages to update. Things like perl, php, and mysql scare the dickens out of me.

Is there an "undo"?

I.e. I run yum update *, but then I notice that something doesn't work and I can run yum undo?

Do I trust that everything will auto work and there will not be any issues? As you can tell I am not too familiar with YUM.

Old 09-30-2009, 12:23 PM   #2
Registered: Jan 2006
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Have no fear, yum is your friend. I have as yet to run into a problem with an update from yum. I been using Fedora for the last two years non-stop, and on and off for the last 4 years.
Old 09-30-2009, 12:26 PM   #3
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Location: chicago, IL
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what cpuobsessed said.
Old 09-30-2009, 12:30 PM   #4
Registered: Jan 2005
Location: Shropshire, England, UK
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The packages you have mentioned are already installed, yum is simply telling you that there are updated versions of these packages.

If you say yes yum will download the packages and will then run a transaction check to ensure that the process will finish correctly.

If any configuration files are updated then yum will either create the new version of the config in a <filename>.rpmnew file or will save your old file as <filename>.rpmsave

I have done this process hundreds of times and very rarely have any problems and in the cases where I have yum has informed me of them before the packages are updated (i.e. after running the transaction check).
Old 09-30-2009, 12:40 PM   #5
LQ Newbie
Registered: May 2004
Location: North Carolina
Distribution: Fedora Core 2 1.92 V3
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Fear Not

You need to read the man page for yum.
There is an uninstall option in Yum
"yum remove 'package'", if you are unsure what to remove "fear not" you can always reload Linux.

You said:
"Things like perl, php, and mysql scare the dickens out of me. "

These programs are good. You may not need them, but a utility that you use might so I would be careful

Linux is generally well documented. You type "info yum" or "man yum"

and you will get a page similar to the one listed below which I copied from the web. This may seem a little cryptic at first but it is really just terse.
After you learn the way Linux works, you will realize that it is there as a reminder as no one can remember everything.

After a while, it becomes easier to read. It makes learning Linux a lot easier and cheaper than using the snow blower approach that Microsh*t uses. You already know that Wind*ws su*ks or else you wouldn't have discovered Linux, so I'll shut up already.

You will often see the word RTM or RTFM which stands for Read The Man(ual) page or Read The F***** Man(ual) page.

If you are worried about something being loaded that you do not know what it is do a web search or RTM.

Linux is remarkably well maintained, to be a community hack. If you are really interested in learning Linux, find a used bookstore somewhere and get a book on the subject. It doesn't have to be the latest edition as basic Linux doesn't require new skill sets and manuals with every edition, Linux like Congress is incrementally taking over the world.
Good luck

yum(8) - Linux man page
yum - Yellowdog Updater Modified
yum [options] [command] [package ...]

yum is an interactive, automated update program which can be used for maintaining systems using rpm

command is one of:
* install package1 [package2] [...]
* update [package1] [package2] [...]
* check-update
* upgrade [package1] [package2] [...]
* remove | erase package1 [package2] [...]
* list [...]
* info [...]
* provides | whatprovides feature1 [feature2] [...]
* clean [ packages | headers | metadata | cache | dbcache | all ]
* makecache
* groupinstall group1 [group2] [...]
* groupupdate group1 [group2] [...]
* grouplist [hidden]
* groupremove group1 [group2] [...]
* groupinfo group1 [...]
* search string1 [string2] [...]
* shell [filename]
* resolvedep dep1 [dep2] [...]
* localinstall rpmfile1 [rpmfile2] [...]
* localupdate rpmfile1 [rpmfile2] [...]

* deplist package1 [package2] [...]

Unless the --help or -h option is given, one of the above commands must be present.

Repository configuration is honored in all operations.

Is used to install the latest version of a package or group of packages while ensuring that all dependencies are satisfied. If no package matches the given package name(s), they are assumed to be a shell glob and any matches are then installed.
If run without any packages, update will update every currently installed package. If one or more packages are specified, Yum will only update the listed packages. While updating packages, yum will ensure that all dependencies are satisfied. If no package matches the given package name(s), they are assumed to be a shell glob and any matches are then installed.

If the --obsoletes flag is present yum will include package obsoletes in its calculations - this makes it better for distro-version changes, for example: upgrading from somelinux 8.0 to somelinux 9.
Implemented so you could know if your machine had any updates that needed to be applied without running it interactively. Returns exit value of 100 if there are packages available for an update. Also returns a list of the pkgs to be updated in list format. Returns 0 and no packages are available for update.
Is the same as the update command with the --obsoletes flag set. See update for more details.
remove or erase
Are used to remove the specified packages from the system as well as removing any packages which depend on the package being removed.
Is used to list various information about available packages; more complete details are available in the List Options section below.
provides or whatprovides
Is used to find out which package provides some feature or file. Just use a specific name or a file-glob-syntax wildcards to list the packages available or installed that provide that feature or file.
Is used to find any packages matching a string in the description, summary, packager and package name fields of an rpm. Useful for finding a package you do not know by name but know by some word related to it.
Is used to list a description and summary information about available packages; takes the same arguments as in the List Options section below.
Is used to clean up various things which accumulate in the yum cache directory over time. More complete details can be found in the Clean Options section below.
Is used to enter the 'yum shell', when a filename is specified the contents of that file is executed in yum shell mode. See yum-shell(8) for more info
Is used to list packages providing the specified dependencies, at most one package is listed per dependency.
Is used to install a set of local rpm files. If required the enabled repositories will be used to resolve dependencies.
Is used to update the system by specifying local rpm files. Only the specified rpm files of which an older version is already installed will be installed, the remaining specified packages will be ignored. If required the enabled repositories will be used to resolve dependencies.
Produces a list of all dependencies and what packages provide those dependencies for the given packages.

General Options

Most command line options can be set using the configuration file as
well and the descriptions indicate the necessary configuration option to set.
-h, --help
Help; display a help message and then quit.
Assume yes; assume that the answer to any question which would be asked is yes.
Configuration Option: assume-yes
-c [config file]
Specifies the config file location - can take http, ftp urls and local file paths.
-d [number]
Sets the debugging level to [number] - turns up or down the amount of things that are printed. Practical range: 0 - 10
Configuration Option: debuglevel
-e [number]
Sets the error level to [number] Practical range 0 - 10. 0 means print only critical errors about which you must be told. 1 means print all errors, even ones that are not overly important. 1+ means print more errors (if any) -e 0 is good for cron jobs.
Configuration Option: errorlevel
-R [time in minutes]
Sets the maximum amount of time yum will wait before performing a command - it randomizes over the time.
Tells yum to run entirely from cache - does not download or update any headers unless it has to to perform the requested action.
Reports the yum version number and exits.
Specifies an alternative installroot, relative to which all packages will be installed.
Configuration Option: installroot
Enables specific repositories by id or glob that have been disabled in the configuration file using the enabled=0 option.
Configuration Option: enabled
Disables specific repositories by id or glob.
Configuration Option: enabled
This option only has affect for an update, it enables yum's obsoletes processing logic. For more information see the update command above.
Configuration Option: obsoletes
Exclude a specific package by name or glob from updates on all repositories.
Configuration Option: exclude
Run with all plugins disabled.
Configuration Option: plugins

List Options
The following are the ways which you can invoke yum in list mode. Note that all list commands include information on the version of the package.

yum list [all | glob_exp1] [glob_exp2] [...]
List all available and installed packages.
yum list available [glob_exp1] [...]
List all packages in the yum repositories available to be installed.
yum list updates [glob_exp1] [...]
List all packages with updates available in the yum repositories.
yum list installed [glob_exp1] [...]
List the packages specified by args. If an argument does not match the name of an available package, it is assumed to be a shell-style glob and any matches are printed.
yum list extras [glob_exp1] [...]
List the packages installed on the system that are not available in any yum repository listed in the config file.
yum list obsoletes [glob_exp1] [...]
List the packages installed on the system that are obsoleted by packages in any yum repository listed in the config file.
yum list recent
List packages recently added into the repositories.
Specifying package names
All the list options mentioned above take file-glob-syntax wildcards or package names as arguments, for example yum list available 'foo*' will list all available packages that match 'foo*'. (The single quotes will keep your shell from expanding the globs.)

Clean Options

The following are the ways which you can invoke yum in clean
mode. Note that "all files" in the commands below means "all files in currently enabled repositories". If you want to also clean any (temporarily) disabled repositories you need to use --enablerepo='*' option.
yum clean packages
Eliminate any cached packages from the system. Note that packages are not automatically deleted after they are downloaded.
yum clean headers
Eliminate all of the header files which yum uses for dependency resolution.
yum clean metadata
Eliminate all of the files which yum uses to determine the remote availability of packages. Using this option will force yum to download all the metadata the next time it is run.
yum clean dbcache
Eliminate the sqlite cache used for faster access to metadata. Using this option will force yum to recreate the cache the next time it is run.
yum clean all
Runs yum clean packages and yum clean headers as above.


Specifying package names
A package can be referred to for install,update,list,remove etc with any of the following:

For example: yum remove kernel-2.4.1-10.i686

Yum can be extended through the use of plugins. A plugin is a Python ".py" file which is installed in one of the directories specified by the pluginpath option in yum.conf. For a plugin to work, the following conditions must be met:

1. The plugin module file must be installed in the plugin path as just described.

2. The global plugins option in /etc/yum.conf must be set to '1'.

3. A configuration file for the plugin must exist in /etc/yum/pluginconf.d/<plugin_name>.conf and the enabled setting in this file must set to '1'. The minimal content for such a configuration file is:


enabled = 1

See the yum.conf(5) man page for more information on plugin related configuration options.


See Also

yum.conf (5)


See the Authors file included with this program.

There of course aren't any bugs, but if you find any, you should first consult the Faq mentioned above and then email the mailing list: or filed in bugzilla.
Referenced By
mock(1), opyum(8), pirut(8), pup(8), puplet(8), system-cdinstall-helper(8), system-install-packages(8), yum-updatesd(8)
Old 09-30-2009, 07:32 PM   #6
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See here for list of common examples of yum usage.
As mentioned above, update means update; it'll only update to your current requirements.
(if it mentions install, that's because a current pkg has a dependency to satisfy; no worries)

You'd have to use the keyword 'install' instead to install a completely new pkg.
Note also that yum is failsafe ie if it has an issue, it'll refuse to do the updates and it will tell you why.

Last edited by chrism01; 09-30-2009 at 07:34 PM.
Old 10-01-2009, 08:52 AM   #7
Registered: Jan 2006
Distribution: Fedora, Ubuntu, Slackware
Posts: 56

Rep: Reputation: 15
Another thing about yum is if it is the middle of a process (update, install, etc.) and the network goes down it can continue without having to re-download what it already downloaded.


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