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Issue #4 February 2005
Red Hat's customer service team receives technical support questions from users all over the world. As they are received, Red Hat technicians add the questions and answers to the Red Hat Knowledgebase on a daily basis. Individuals with a redhat.com login are granted limited access. Red Hat Enterprise Linux subscribers are granted full access — with expanded categories and advanced search capabilities. Every month, Red Hat Magazine offers a preview into the Red Hat Knowledgebase by highlighting some of the most recent entries.
This month's Tips & Tricks provide helpful information to Enterprise Linux 4 users and administrators.
The system tool called system-config-packages (System Settings ->
Add/Remove Applications) allows for package addition and removal via a
graphical interface. In its normal operation, it prompts for packages
from one of the installation CD, which can be inconvenient. Many
people might find that it's better to copy all the packages from the
four distribution CDs (or from ISO files) onto the local system. This
way there's no looking for and shuffling of CDs when you want to add
packages. For example, make the local repository under /data/rhel3asu4 using the following steps:
mkdir -p /data/rhel3asu4mount /mnt/cdrom cp -a /mnt/cdrom /data/rhel3asu4/ cp /mnt/cdrom/.discinfo /data/rhel3asu4/ umount /mnt/cdrom find . -name TRANS.TBL -exec rm -f {} \; (repeat for each disc, except you only want .discinfo from disc 1)
Having done that, the following command line option allows the
packaging tool to find packages on the local disk (the command might
be redhat-config-packages on older
systems):
system-config-packages --tree=/data/rhel3asu4/
Points to note:
--isodir instead of --tree.
By default, Red Hat Enterprise Linux 4 is not configured to allow
requests for X11 forwarding. When connecting to an SSH server you must
specify the -X or -Y option on the command line as per the
following example:
ssh -X username@hostname
Alternatively, you can omit the command line option if you enable
the The In the Now when connecting to the remote SSH server as this user, there is
no need to specify any additional flags. The connections forward X11
session by default. The new Nautilus uses a spatial mode, where each folder that is
clicked on opens a new folder. Many people believe that this is an
improvement in usability while others do not like the way that the new
Nautilus works. It is easy to revert Nautilus back to its old "Browser mode" by
issuing the command below as the current user: You may have to log out, then back in again for the changes to take effect. To change this back to its original behavior issue the command: Nautilus can be further customized by using the "Configuration Editor" in the System Tools menu. The Red Hat Enterprise Linux 4 kernel uses digital signatures on
all the kernel modules that come with the kernel RPM. These signatures
are checked during the loading of kernel modules and if the signature
is not present, the module will get an (U) printed after it's name in
oops output. This technology allows Red Hat support to better respond to
customer issues regarding kernel oopses but otherwise imposes no
restrictions whatsoever. If you see a module that should come from the kernel RPM (such as
the e1000 Ethernet driver) but that still is marked with (U), then you
are not using the driver that Red Hat originally shipped. This can
happen if you (or the OEM you bought your pre-installed Red Hat
Enterprise Linux 4 system from) used a driver disk or the DKMS tool to
install a modified driver. The Renaming the file to have a To view the file it must be extracted using the Then use the The initrd file has a nash script that is used to load kernel
modules. View the script with the command Firefox is the default web browser in Red Hat Enterprise Linux
4. To change the default location of where Firefox downloads files, use
the following instructions:
This article is protected by the Open Publication License, V1.0 or later. Copyright © 2004 by Red Hat, Inc.ForwardX11 option in
your ~/.ssh/config
.ssh directory exists in the home
directory of the user that is attempting to connect to the remote
server. When you attempt to connect to a remote server the .ssh directory is created automatically..ssh directory, create a file
called config. This file may already
exist, if so, append the following line:
ForwardX11 yes
The new Nautilus opens a new window every time I click a folder. How can I change it back to the old behavior?
by Wade Mealing
gconftool-2 --type bool --set /apps/nautilus/preferences/always_use_browser true
gconftool-2 --type bool --set /apps/nautilus/preferences/always_use_browser false
I see a (U) after some modules in a kernel oops on Red Hat Enterprise Linux 4, what does this mean?
by Arjan van de Ven
How do I view my initrd file in Red Hat Enterprise Linux 4?
by Michael Kearey
initrd file is a compressed cpio archive of a temporary root filesystem. To
view the contents of the file, copy it to a directory and name it with
the .gz file extension:
cp /boot/initrd-<version>.img /tmp/initrd-<version>.gz
.gz
extension allows the file to to be decompressed with gzip. Decompress the file with the following
command:
gunzip initrd-<version>.gz
cpio command:
mkdir initrd
cd initrd
cpio -cid -I ../initrd-<version>
tree command to view the contents:
.
|-- bin
| |-- hotplug -> /sbin/nash
| |-- insmod
| |-- lvm
| |-- modprobe -> /sbin/nash
| |-- nash
| |-- udev
| `-- udevstart -> udev
|-- dev
| |-- console
| |-- null
| |-- ram
| |-- systty
| |-- tty1
| |-- tty2
| |-- tty3
| `-- tty4
|-- etc
| |-- lvm
| | `-- lvm.conf
| `-- udev
| `-- udev.conf
|-- init
|-- lib
| |-- dm-mirror.ko
| |-- dm-mod.ko
| |-- dm-snapshot.ko
| |-- dm-zero.ko
| |-- ext3.ko
| `-- jbd.ko
|-- loopfs
|-- proc
|-- sbin -> bin
|-- sys
`-- sysroot
11 directories, 24 files
cat
init and see what modules are loaded:
#!/bin/nash
mount -t proc /proc /proc
setquiet
echo Mounted /proc filesystem
echo Mounting sysfs
mount -t sysfs none /sys
echo Creating /dev
mount -o mode=0755 -t tmpfs none /dev
mknod /dev/console c 5 1
mknod /dev/null c 1 3
mknod /dev/zero c 1 5
mkdir /dev/pts
mkdir /dev/shm
echo Starting udev
/sbin/udevstart
echo -n "/sbin/hotplug" > /proc/sys/kernel/hotplug
echo "Loading dm-mod.ko module"
insmod /lib/dm-mod.ko
echo "Loading jbd.ko module"
insmod /lib/jbd.ko
echo "Loading ext3.ko module"
insmod /lib/ext3.ko
echo "Loading dm-mirror.ko module"
insmod /lib/dm-mirror.ko
echo "Loading dm-zero.ko module"
insmod /lib/dm-zero.ko
echo "Loading dm-snapshot.ko module"
insmod /lib/dm-snapshot.ko
/sbin/udevstart
echo Making device-mapper control node
mkdmnod
echo Scanning logical volumes
lvm vgscan
echo Activating logical volumes
lvm vgchange -ay
echo Making device nodes
lvm vgmknodes
echo Creating root device
mkrootdev /dev/root
umount /sys
echo Mounting root filesystem
mount -o defaults --ro -t ext3 /dev/root /sysroot
mount -t tmpfs --bind /dev /sysroot/dev
echo Switching to new root
switchroot /sysroot
umount /initrd/dev
How do I change the location of where Firefox, the web browser,
downloads files?
by Sean Boyd