yum (http://linux.duke.edu/projects/yum/)

- Yellow dog Updater, Modified
- utility for managing RPMs on a system
  - easily install RPMs
  - easily keep up-to-date
  - where "easily" means automatic downloading of RPMs and resolution
    of dependencies

- uses "repositories" of RPMs over either FTP or HTTP

Example 1: installing and upgrading packages

- yum -c /etc/yum-internode.conf install php
- yum -c /etc/yum-internode.conf check-update
- yum -c /etc/yum-internode.conf update

- how it works: look in /var/cache/yum/
  - first time download of headers (not for already-installed packages)

Example 2: updates CD

To check what updates need applying and to do so interactively:

mount /mnt/cdrom
yum -c /mnt/cdrom/yum.conf update

look at:
- /mnt/cdrom/yum.conf
- /mnt/cdrom/headers

Example 3: finding RPMs

- yum -c /etc/yum-fresh.conf list

- yum list, yum info
  - support wildcards eg. yum list postg\*
- yum search database

Example 4: upgrading to a new release

- set the repository
- yum upgrade
  - handles "Conflicts"

Setting up a repository

- put some RPMs in a directory (tree)
- yum-arch /that/dir
- make the directory available by ftp, http, or just use it
  through the filesystem
- requires no special server software

Other bits:

- Multiple repositories
  - newest vs. last

- Uses RPM python interface, so is consistent with RPM

- Automated updating with -y:
  /etc/init.d/yum
  /etc/cron.daily/yum.cron

- Sharing a cache with NFS or rsync

- What happens when dependencies can't be satisfied
  yum -c /etc/yum-fresh.conf install php

- yum clean

Example 5: vserver installation

- install a minimal set of RPMs
- install the rest with yum

Things I've noticed:
- can be slow
- can chew up a lot of memory (eg. 100MB)
- doesn't have a download but don't install mode (yet)

Other documentation:
  http://www.phy.duke.edu/~rgb/General/yum_HOWTO/yum_HOWTO/yum_HOWTO.html
  http://www.charlescurley.com/yum.html

Some repositories:
  http://download.fedora.redhat.com/pub/fedora/linux/core/1/i386/os/
  http://download.fedora.redhat.com/pub/fedora/linux/core/updates/1/i386/
  ftp://mirror.internode.on.net/pub/fedora/linux/core/1/i386/os/
  ftp://mirror.internode.on.net/pub/fedora/linux/updates/1/i386/
  http://ayo.freshrpms.net/fedora/linux/1/i386/freshrpms/
  http://ftp.mozilla.org/pub/mozilla.org/mozilla/yum/