Red Hat Enterprise Linux 5

Red Hat Enterprise 5 is the operating system supported by the Computer Systems Lab for the Computer Sciences department.

There is a documentation page for RHEL 5, which contains more information about the new OS. Please visit the CSL web site (http://www.cs.wisc.edu/csl/) and click the "Red Hat Enterprise 5 Information" link.

If you're not sure what version of linux your computer is currently running, you can verify this by looking at the contents of the file '/etc/redhat-release'. If that file contains the word 'CentOS', you should schedule an upgrade.

As always, please contact the lab (email lab@cs.wisc.edu) if you have any other questions.

What Features Are Available?

Red Hat Enterprise 5 uses hald (hardware abstraction layer daemon) in conjunction with gnome-volume-manager to automatically mount and unmount usb-attached storage, as well as cd, dvd, and floppy disks (on computers equipped with suitable hardware). The gnome desktop starts any and all services needed to access removable media, and gnome creates/removes desktop icons for removable storage as it is mounted or unmounted.

For users of other desktop environments, the CSL recommends running gnome-volume-manager to access your removable media. This can either be started ad-hoc from the command line, or included in your session startup file ( ~/.xsession typically). The eject command can be used (as in eject /media/THING_YOU_WANT_UNMOUNTED) to force buffers to be flushed to your device before it is unmounted. Substitute the appropriate mount name of your device for THING_YOU_WANT_UNMOUNTED.

Please contact the lab if you encounter problems mounting your removable media.

Gnome 2.16 is the default desktop environment for RHEL 5.

Other new software includes the skype internet phone tool, the vlc media player, and the finch modular messaging client.

How Much Disk Space Will I Have?

The default Red Hat Enterprise 5 install requires approximately 46 GBytes of disk space. With a 80 GByte disk, this would leave 21 GBytes in /scratch for local storage. Red Hat Enterprise 5 can be installed on disks as small as 80 GB.

What Are The Differences In Available Software?

Wherever possible, all programs that were available on previous linux distributions will also be available for RHEL 5. There are some situations where support has been dropped for a program either by Red Hat or by upstream maintainers. The CSL will deal with these on a case-by-case basis.

In the past, many programs that were available in /s/std/bin were also available in /usr/bin. Because of the increase in the volume of software installed, the nature of security vulnerabilities, and in an effort by the CSL to make the best possible use of resources, it has become impractical to maintain this duplication. Therefore, beginning with RHEL 5, most software that is available in /usr/bin has been removed from /s/std/bin. The CSL will continue to provided needed up-to-date software in /s (e.g. gcc, java, and others) for those that need these updates.

If you are unsure of whether or not a particular application is available for RHEL 5, you can check for its availablity by logging in to our test system, rhel5-test.cs.wisc.edu, and checking for yourself.

Release Notes

• vendor release notes: http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Release_Notes/index.html

The following caveats exist with RHEL 5. Workarounds are listed if known.

• Use /usr/bin/cdrecord to record all CD and DVD .iso images, as in: /usr/bin/cdrecord ISO_IMAGE . The only option that may need to be specified is -dao which may be required on some drives. You should not need device=, speed=, or other options. You can always use -v to show more information about the burn. Some individuals have reported failed burns when writing CDs/DVDs from .iso files in /afs. We strongly encourage copying .iso files to your computer's local disk and burning from there.

• When using older IDE CD and DVD burners with cdrecord or other CD/DVD burning programs, it may be necessary to specify the raw device name (/dev/hda, /dev/hdb, etc.), as in: /usr/bin/cdrecord -sao dev=/dev/hda ISO_IMAGE. Otherwise, proper drivers won't be loaded and the media will be deemed "incompatible" and burning will fail. This is not an issue for newer SATA-based burners.

• A new version of groff has been installed, which outputs documents for screen viewing using different escape sequences. If a user has a PAGER environment variable set to use the less command, the PAGER options must include -r or -R to view the document correctly. This most often shows up with the man command.

• There is an afs issue of data appended to a file on one workstation not being immediately available on other workstations without a close()/open() or stat() of the file in question.

• The sound subsystem on RHEL is initialized with the volume control set to zero. Use the gnome-volume-control program to increase the volume control(s) to a comfortable level. Note: you may need to set volume levels for both your sound card and the generic OSS device (Change Device under the File menu) in order to listen to audio sources.

• The network packet sniffer formerly known as ethereal is now called wireshark. Run wireshark instead of ethereal. The command-line syntax is the same.

• Most programs available in /usr/bin have been removed from /s/std/bin. Scripts depending on /s/std/bin programs may need to be adjusted to use $PATH instead.

• The xloadimage programs, including xsetbg and uufilter, are no longer available. We suggest using display, xv or xsri as replacements.

• PostScript and PDF viewers gv, ggv and ghostview are no longer available. We suggest using mgv for viewing PostScript files and either acroread or xpdf for PDF documents. You may also use the Gnome evince program for viewing PostScript and PDF files.

• Nvidia Corporation has been removed support for older video cards from their linux driver. Because of this, video acceleration for Nvidia hardware old than 5xxx chipsets will be handled by the MESA drivers. Please contact the CSL if you have questions about whether or not your video hardware will be supported.

• xlock (and xglock) will no longer be included in /s/std/bin. We suggest you use gnome-screensaver instead. To use gnome-screen-saver:
  • Run /usr/bin/gnome-screensaver in advance, such as at login time
  • Run /usr/bin/gnome-screensaver-command -a to lock the screen

• xcalc is no longer available. We suggest you consider using gcalctool or gnome-calculator for normal calculator tools, or free42 for an RPN-based calculator.

• Xstats is no longer available to display motd, printer and disk quotas. The new application is csl_motd now.

• In accordance with current security best practices, the TCP socket for the X server has been disabled. Users will need to tunnel X sessions via ssh, or find an alternate means of displaying remote applications on their Red Hat Enterprise 5 desktop.

• As was the case with CentOS 4, ntfs file systems cannot be mounted on Red Hat Enterprise hosts, due to the proprietary nature of ntfs. You can, however, mount ntfs file systems on removable media in a Windows VMware virtual machine. Please contact the lab if you have difficulty mounting your removable media.

• SCIM, or Smart Common Interface Module, has been disabled by default for Red Hat Enterprise 5 workstations. Users who wish to use SCIM support for entering foreign alphabets/languages may enable this feature under the GNOME desktop by selecting System -> Preferences -> More Preferences -> Input Method and enabling SCIM for their GNOME session. Users of other windowing systems may opt to run /etc/X11/xinit/xinput.d/scim.conf to start the SCIM service processes for their desktop session.

What Versions Of Red Hat Software Will Be Installed?

To see the current software install set for RHEL 5, please ssh to rhel5-test.cs.wisc.edu and run the command:

rpm -qa

This will display the entire set of rpms included in the base install.