List files in an rpm file

rpm -qlp mysql5-0.rpm

Rename files which match specific criteria

This renames all files within the current working directory from .exe to .exeold. This is useful if you are trying to rename any file extension from one to another.

for file in *.exe ; do mv $file `echo $file | sed 's/\(.*\.\)exe/\1exeold/'` ; done

Simple bash for loop

for kernelrpm in kernel-smp-2.6.9-5.EL kernel-smp-2.6.9-34.EL kernel-smp-2.6.9-67.0.1.EL kernel-utils-2.4-14.1.117

do rpm -e $kernelrpm

done

Boot FreeBSD with Grub

If you have installed FreeBSD (or any operating system) and a partition and then later installed Linux (or any operating system with Grub) on another partition and can't get the latter to boot the former, add this line to /boot/grub/menu.lst

# For booting FreeBSD
title  FreeBSD 7.0
root   (hd0,1)
chainloader +1

In this case, the partition was /dev/sda2 which contained FreeBSD. Modify it for your needs.

Coraid documentation

I was able to do quite a bit of technical writing with Coraid. It is useful for those of you using AoE technology. I wrote all of the quickstart documentation here:

http://www.coraid.com/RESOURCES/Quickstart-Documentation

Also, I wrote the driver installation guides here:

http://www.coraid.com/SUPPORT/AoE-Drivers

A Tag Cloud that works with Blogger

I have spent a great deal of time trying to find a Tag Cloud generator that works with Google Blogger. Finally, I found one.

http://www.compender.com/2007/12/simple-tag-cloud.html

LVM snapshots

Here is a script to create LVM snapshots in Linux. It is a skeleton only provided for your modification and my reference, but I am using AoE storage as my PV.

#create PV

pvcreate /dev/etherd/e1.0

#create VG

vgcreate cascade /dev/etherd/e1.0

#create LV

lvcreate cascade -n original -L 500G

#make XFS filesystem

mkfs.xfs /dev/cascade/original

#mount (and use) LV

mount /dev/cascade/original /mnt

#freeze filesystem (will hang processes that are using IO on /mnt)

xfs_freeze -f /mnt

#create snapshot of original (works best if it is the same size)

lvcreate -s /dev/cascade/original -n backup -L 500G

#mount snapshot

mount -o nouuid,ro /dev/cascade/backup /mnt2

#backup directory with rsync or backup utility

#unmount LV

umount /mnt2

#remove snapshot

lvremove /dev/cascade/backup

#additional information is found here: http://arstechnica.com/articles/columns/linux/linux-20041013.ars and here: http://tldp.org/HOWTO/LVM-HOWTO/snapshots_backup.html

List largest (or smallest) files

If you want to find the largest files in a directory which are consuming precious space, you can use the following command:

openSuSEServer:~ # du -kh /var | sort -n | tail

then, to sort the smallest files, use the inverse command:

openSuSEServer:~ # du -kh /var | sort -n | head

Adding a subject to an e-mail link

Usually, an e-mail link would look like this:

<a href="mailto:sales@coraid.com">E-mail sales </a>

But to add a subject line to the e-mail when someone clicks the link and sends an e-mail is done with the one of the two following examples:

<a href="mailto:sales@coraid.com?subject=New%20sales%20inquiry">E-mail sales</a>

or

<a href="mailto:sales@coraid.com" title="New sales inquiry">E-mail sales</a>

The first one works every time that I have used it, but the second one is an HTML compliant way of doing the same thing.

Coraid blogging

I am now working for Coraid as a systems engineer. I will be blogging professionally at Coraid's blog, and also will be responsible for much of the company's new documentation, which has kept me very busy so far. I will continue to blog here when I find interesting things to blog about.

Dates within crontab

If you want to add dates to backups or logs, like mythtvDB27062008.sql within crontab, do the following:

0 0 * * * /usr/bin/mysqldump -u mythtv -pPassword mythconverg > /mythtv/recordings/mythtvDB`date +%d%m%Y`.sql

The key is the backquotes around the `date +%d%m%Y` command. This will backup a MythTV MySQL database to a file like this: /mythtv/recordings/mythtvDB27062008.sql every night at midnight.

Change hostname

To change the name of the computer's name (hostname) do the following:

#echo <hostname> > /etc/HOSTNAME

Example:

#echo earth > /etc/HOSTNAME

Mount ISO images as physical devices

Here is a great how-to with mounting ISO images as though they were a physical device like a CD-ROM or DVD drive:

http://www.cyberciti.biz/tips/how-to-mount-iso-image-under-linux.html

Tag cloud generation

Of the many that I have tried, this website is the best for tag cloud generation:

http://www.tagcloud-generator.com/index.php

Execute any custom command on bootup (Ubuntu, Debian)

This command is for anything that you would like to execute after the system has been started and all of the scripts in /etc/init.d/ have been run. If you want them to execute afterwards, put it in

/etc/rc.local

This is rather useful for network mounts, changes to hardware configuration, or custom programs that need to be started at boot. Make sure to make the file executable through the command: $sudo chmod +x /etc/rc.local

Mount a cdrom from the command line

To mount a cdrom (or DVD) from the command line, do the following:

#mount -t iso9660 -o ro <device> <mountedDirectory>

Example:

# mount -t iso9660 -o ro /dev/cdrom /media/cdrom

Note: make sure that /media/cdrom exists.

Configure a wireless connection from the command line

Here is how to configure a wireless network interface from the command line in Ubuntu.

http://www.stoltenow.com/archives/2006/12/ubuntu_configur.html

Copying DVDs from the command line

Would you like to store a backup of your DVD collection to disk? Here is how, using vobcopy, a lossless copy:

#vobcopy [--large-file] [-verbose] [-input-dir DVD_DEVICE]

Example:

#vobcopy -l -v -i /dev/dvd

Execute any custom command on bootup (SuSE or Red Hat)

This command is for anything that you would like to execute after the system has been started and all of the scripts in /etc/init.d/ have been run. If you want to execute these commands before any of these scripts, but the commands in the new file:

/etc/init.d/before.local

If you want them to execute afterwards, put it in

/etc/init.d/after.local

This is rather useful for network mounts, changes to hardware configuration, or custom programs that need to be started at boot. Make sure to make the file executable through the command: chmod +x /etc/init.d/after.local

The other option is to edit the /etc/rc.d/rc.local and do that same there.

His name.... is Linux

This is a powerful IBM commercial about Linux.

Mythweb at its best

Mythweb, a component of MythTV, allows you to stream your own recorded videos, shows or movies from the Internet in a YouTube-like interface. Here is an example. One more reason MythTV beats the socks off TiVO.

Why Webmin is the best tool for Systems Administrators

In the SysAdmin world, Webmin is the best invention next to sliced bread. It is a compete, web-based administration interface for dozens of different systems. Not only does it support a plethora of operating systems, but it is much better than Red Hat's system-config-* and almost as good as Novell's Yast. It knocks the socks off any other administration tool that I have seen. You can download the package for your distro at Webmin's Website I guess you can call me a Webmin fanboy.

Lexmark Z645 Printer on Ubuntu Linux

This post, is how you can get a Lexmark Z645 Printer to work within Ubuntu 7.04, 7.10, 8.04 and later. It is most useful. http://ubuntuforums.org/archive/index.php/t-616097.html

Writing ISO files from the commandline

Maybe you want to rip a data CD or DVD into an ISO formatted file. Here is how to do it from the command line:

$wodim -v dev=<device> [speed] <trackName.iso>

For example:

$wodim -v dev=/dev/scd0 speed=4 puppy-3.01-seamonkey.iso

Backup or restore a MySQL database

They say that a system administrator is only as good as his last backup. If you need to backup or restore a MySQL database, you can execute these commands:

Backup the database:

$mysqldump -u <adminuser> -p <password> <databasename> > <databasebackupfile.sql>

For example:
$mysqldump -u root -p myPass mythconverg > mythdatabasebackup.sql

Restore the database:

$mysql -u <adminuser> -p <password> <databasename> < <databasebackupfile.sql>

For example:
$mysql -u root -p myPass mythconverg < mythdatabasebackup.sql

Repair a MySQL database

Sometimes you can do something to your MySQL database which causes corruption. You can fix this with the following command:

$mysqlcheck <database> -u <adminuser> -p <password> --auto-repair

For example:

$mysqlcheck mythconverg -u root -p myPass --auto-repair

This will automatically repair any corruption found within the database schema.

Align and clean printer heads for a Lexmark printer

If you have a Lexmark printer within Linux, it may be difficult to align or clean the printer heads as these utilities are nonexistent within cups. I have a Lexmark z645 printer. The workaround is to use the lpr utilities to get the job done. With some modification, this should work for most printers, not just Lexmark ones.

To align printer heads:
#lpr -P <printernamewithincups> -o raw <pathtoalignutility.out>

For example:
#lpr -P Lexmark_640_Series -o raw /usr/local/z600llpddk/utility/lxbcalgn.out

To clean printer heads:
#lpr -P <printernamewithincups> -o raw <pathtocleanutility.out>

For example:
#lpr -P Lexmark_640_Series -o raw /usr/local/z600llpddk/utility/lxbccln.out

The -o raw allows the job to be performed without going through MIME filters. Note that the paths may be different depending on your printer's driver. Use the command:

#find / -iname *.out to locate the correct path for the align and clean utility.

Past writings for the BYU-I Linux/Unix Society

I have been the BYU-Idaho Linux/Unix Society President for four semesters. During that time, I have had the opportunity to present articles on various themes. Here are links to those documents:

How to install Linux within VMWare (PDF)
Gaming in Linux (PDF)
Multimedia within Linux (PDF)
Build your own TiVo with MythTV (PDF)

The society's website is located here.

Why Masters of the Universe?

When I was younger, my brother and I were enthralled with He-Man and the Masters of the Universe cartoon show. We enjoyed playing with the action figures and imagining we were He-Man. This blog is a throwback to the idea of overwhelming power over evil. In this case, through using Linux.