neat trick to find filesystem associated with a label
findfs LABEL=[label]
This command can also be used to locate filesystems with UUID (Universally Unique Identifier) by replacing LABEL with UUID:
findfs UUID=[uuid]
February 13, 2007
December 15, 2006
December 14, 2006
How to extract an rpm files contents
How to extract an RPM package without installing it | nixCraft
Syntax is as follows:
rpm2cpio myrpmfile.rpm
rpm2cpio - < myrpmfile.rpm
rpm2cpio myrpmfile.rpm | cpio -idmv
Installing HP ILO firmware updates
Component for Linux - HP Integrated Lights-Out, 1.89 allows you to install the latest ILO firmware updates without having to unpack on Windows and create to stupid boot floppies.
you can either update from the command line, or extract the bin file and update in the ILO's web interface.
December 12, 2006
Cloning NTFS from linux.
December 04, 2006
Locale issues under linux
I was having a problem with locale errors. I am running Ubuntu Edgy.
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = (unset),
LANG = "en_US.UTF-8"
are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
I tried to run
# dpkg-reconfigure locales
This didn't help. I then ran:
# locale-gen en_US
# locale-gen en_US.UTF-8
and that fixed it.
November 13, 2006
Bash programming methodology
IBM Developerworks had an article about bash functions. I found this little ditty tucked in the article and I liked it.
These basic steps and recommendations can be applied to many client/server applications that run in Linux.
Document the prerequisites and main sequence for running scripts
Divide actions into logical groups
Develop an execution sequence based on a common usage scenario
Provide comments and instructions in each shell script
Make an initial backup to create a baseline
Check for input parameters and environment variables
Try to provide "usage" feedback
Try to provide a "silent" running mode
Provide one function to terminate the script when there are errors
When possible, provide functions that do a single task well
Capture the output of each script, while watching the output being produced
Inside each script, capture the return code of each line command
Keep a count of the failed transactions
Highlight the error messages for easy identification in the output file
When possible, generate files "on the fly"
Provide feedback on the progress of the execution of the script
Provide a summary of the execution of the script
Try to provide an output file that is easy to interpret
When possible, provide cleanup scripts and a way to return to the baseline
- Document the prerequisites and main sequence for running scripts
- Divide actions into logical groups
- Develop an execution sequence based on a common usage scenario
- Provide comments and instructions in each shell script
- Make an initial backup to create a baseline
- Check for input parameters and environment variables
- Try to provide "usage" feedback
- Try to provide a "silent" running mode
- Provide one function to terminate the script when there are errors
- When possible, provide functions that do a single task well
- Capture the output of each script, while watching the output being produced
- Inside each script, capture the return code of each line command
- Keep a count of the failed transactions
- Highlight the error messages for easy identification in the output file
- When possible, generate files "on the fly"
- Provide feedback on the progress of the execution of the script
- Provide a summary of the execution of the script
- Try to provide an output file that is easy to interpret
- When possible, provide cleanup scripts and a way to return to the baseline
September 20, 2006
Using getopts with bash scripting
September 03, 2006
Bash gui programming
July 29, 2006
Using Imutability for disk backups
Protect harddisk-based backup from accidental removal
Use chattr command changes the file attributes on a Linux second extended file system so that you will stay away from accidentally removing your backup files with rm -rf.
apt utilities
July 27, 2006
A nice review
Book review: Linux® Troubleshooting for System Administrators and Power Users by David Carmichael, et al is a nice review of the book I co-wrote. Check it out..
July 18, 2006
Useradd fails
I was receiving an error on an NFS booted RH linux system.
# userdd -m foo
useradd: cannot rewrite password file.
The lock files in /etc looked ok. Specifically /etc/.pwd.lock was empty. I verified I was logged in as root, and I ran pwck and grpck to confirm that the passwd and grp files were FUBAR.
This turned out to be caused by SElinux. SElinux can't cope with ReiserFS, JFS, or NFS. I am sure there are probably others as well. It can handle ext2/3 and XFS. I would bet it works on GFS but I haven't tested. Look at the extended entry for more details.
You can see how to disable SElinux here.
How to disable SElinux
Edit /etc/sysconfig/selinux
Change the SELINUX variable to disabled.
SELINUX=disabled
Now you can reboot and run:
# selinuxenabled ;echo $?
-256
Fromo the man page:
selinuxenabled Indicates whether SELinux is enabled or disabled. It
exits with status 0 if SELinux is enabled and -256 if it is not
enabled.
VMplayer retreivable via apt-get
From VMTN Blog
...VMware Player is now available in Ubuntu Dapper repositories. Reading the comments, it looks like your mileage may vary, but for most, a sudo apt-get install vmware-player will do the trick. "No tarballs, no compiling kernel modules, no banging rocks together."
July 17, 2006
LinuxCOE
June 08, 2006
Backula
Detailed Bacula Network Backup Implementation Guide | Ubuntu Linux Ihav started using Mozy to backup my laptop, but backula looks pretty good as well.
May 24, 2006
SSH + Squid
SSH + Squid = Private Browsing This is handy for secure surfing at public wifi hotspots.
May 16, 2006
Bash keybindings
May 15, 2006
Apache Load Balancing
May 05, 2006
Vmware router
May 03, 2006
Bash Daemon
A Bourne Again Daemon This looks handy.
April 13, 2006
Static routes
nixCraft: Configuring static routes in Debian or Red Hat Linux systems is a great article about static routes. The syntax always drives me nuts.
April 09, 2006
April 06, 2006
Python pefr tips
PythonSpeed/PerformanceTips is a good guide to optimizing your python code to be more efficient.
March 29, 2006
How to backup dvd's with ubuntu
Alternative rc script managers
I know it seems like there are a hundred rc script managers for linux. Here are the one I know about:
1. ntsysv and tksysv - RedHat / FC only
2. chkconf - Used a bit more widely (RedHat, FC, SuSE)
3. service - A RedHat/ FC only way to stop and start services
4. update-rc.d - debian / ubuntu utility
5. redhat-config / system-config - The RedHat / FC management GUI
6. yast - SuSE system management GUI
7. rcconf - debian based
8. insserv - SuSE based
9. BUM - debian based gui
Any others that you know of? Please comment
rc.local in Ubuntu
I am running Breezy Ubuntu and I don't have an rc.local on the system. I don't know if this is a concious decision or an oversite. Here are the steps I used to create one.
1. create /etc/init.d/rc.local
#!/bin/sh
#rc.local
echo 1024 > /proc/sys/dev/rtc/max-user-freq
2. run the following command:
# update-rc.d rc.local start 99 2 3 4 5 .
Hattip to Ubuntu Blog
for the starting point.
Top and Htop
I was reading an article on Using Top More Efficiently, and contemplating how much I dislike top. It is anti-user friendly. In the comments they mentioned htop
I installed it and it ROCKS! It addresses a lot of the limitations of top. It is much more user friendly.
March 13, 2006
htaccess generator
January 13, 2006
Must see Linux tool
Create a custom LinuxCOE 4 install image and see how awesome it makes system management. This tool makes installation, and provisioning systems so easy it is not even funny...
January 09, 2006
Ubuntu updates
I found a couple of interesting Ubuntu items.
I found a nice script to update Firefox in Breezy to 1.5, and then I accidentally found a link to another auto configurator for Ubuntu. Automatix seems similar to Easy Breezy (nee Easy Ubuntu).
January 04, 2006
mkfs fails
I was getting the following error trying to mkfs a partition.
mkfs.ext2: No such device or address while trying to determine
filesystem size
After some plonking I realized that the fdisk I used to create the partition was the issue. Normally a reboot is needed, and I couldn't reboot at that time. I found this handy command to reread the partition table:
partprobe /dev/sda
December 20, 2005
Our Linux Troubleshooting book
Amazon.com: Linux Troubleshooting for System Administrators and Power Users: Books: James Kirkland,David Carmichael,Chris Tinker,Greg Tinker is now available for pre-order. This is he book I have cowritten. Please buy as many as you can. I will have more details on it shortly.
October 31, 2005
How to get linux version
To get the version information from ubuntu try "cat /etc/lsb-release".
To get the version information from Red Hat Enterprise Linux try "cat /etc/redhat-release"
To get the version information from Fedora Core try "cat /etc/fedora-release"
To get the version information from Suse try "cat /etc/SuSE-release"
October 18, 2005
Easy Ubuntu
Easy Ubuntu 2.3 - Bienvenue chez moi ! looks great. I have an Ubuntu install. This looks to simplify customizing it.
October 12, 2005
Using ssh-agent
Using ssh-agent with ssh is handy. I got tired of typing the passphrase in for my key. I love the .profile code to automate starting ssh-agent.
October 11, 2005
Installing VMware 5.0 workstation on SUSE Linux 10.0
September 20, 2005
LPIC 2 test prep
September 08, 2005
htaccess cheatsheet
The the jackol’s den � htaccess Cheatsheet is a handy guide to setting up htacess protection with apache.
September 07, 2005
Ext filesystem tools for windows
TinyApps.Org : Blog has a list of tools to access ext2/3 filesystems under windows.
June 27, 2005
Another SuSE annoyance
Editing scripts with Vim gives a good hint on enabling color in vim. SuSE has it disabled by default. I am not sure why. Annoying.
June 25, 2005
How to install vmware 5 under Suse
After banging my head against the wall I found this from LinuxQuestions.org - Step by Step way to make SUSE 9.3 VMWARE ready ?? - where Linux users come for help
June 13, 2005
nc6000 debian howto
Installing Debian on a HP Compaq NC6000 Laptop is a good guide to installing Debian on this laptop. This is the laptop I have.
/dev/hda {
io32_support = 3
dma = on
mult_sect_io = 16
interrupt_unmask = on
transfer_mode = 69
}
Fedora Core 4 out
Well it looks like FC4 is out. There is a torrent available as well. One interesting idea is to update via yum. You can check it out at the YumUpgradeFaq - Fedora Project Wiki
Update: I found that this site actually had more detailed information.
June 07, 2005
World to end tomorrow. Linux hit hardest.
Why does it seem that a major development in the computer biz always leads John Dvorak to say it will hit Linux the hardest. He is definiately a playa hater. Those who can do.... I am so tired of these effite mac biggots.
March 29, 2005
How to run a 32 bit binary under 64 bit linux
Use the linux32 command as a prefix
Ie.
$ uname -m
X86_64
$ linux32 bash
$ uname -m
I686
March 15, 2005
WEP Key creator
March 14, 2005
Grub tutorial
Grub From the Ground Up is a great GRUB tutorial. Lord knows I need GRUB help. I knew lilo pretty well. For some reason I use grub just enough to forget it between problems...
March 13, 2005
IMAP craziness
I use Cyrus-imapd for my imap server. It can be a bit fidgety at times. I have had to learn cyradm (which I always forget to su to cyrus to use) and administer it. It is much more complex than UW-IMAP which I used before.
Last week I suddenly started having this odd problem. No matter what I did the messages in my mail box would stay flagged as unread. It was driving me nuts. I found the following error in /var/log/maillog:
Mar 13 20:49:04 sanctus imaps[20910]: DBERROR: skiplist recovery /var/lib/imap/user/j/jtk.seen: ADD at 3FCC exists
Mar 13 20:49:04 sanctus imaps[20910]: DBERROR: opening /var/lib/imap/user/j/jtk.seen: cyrusdb error
Mar 13 20:49:04 sanctus imaps[20910]: Could not open seen state for jtk (System I/O error)
I then removed the /var/lib/imap/user/j/jtk.seen file. I then ran:
touch jtk.seen
chown cyrus.mail jtk.seen
chmod 600 jtk.seen
I restarted cyrus-imapd and that fixed it.
Prior to that I had tried running reconstruct on the mailbox to no avail. That was an odd one...
UPDATE: I found a nice cyrus site that has this fix and a few others. It also has the procedure to create a shared mailbox. Nice!
NeroLinux
Nero now has a version of their great software free for Linux. Check it out.
March 03, 2005
New psp for RHEL 4.0
For those of you playing with RHEL4, here is where you can get the PSP for it.
March 01, 2005
Agressive paging instead of swapping
The 2.6 kernel allows you to tune this.
# echo 10 > /proc/sys/vm/swappiness
This will favor text/data pages rather than buffercache for RAM.
February 28, 2005
GPL Bios?
January 30, 2005
Vim and vigor
An interesting article about the best way to use vim.
January 10, 2005
Linux system recovery solutions
I am looking at sys imaging and recovery solutions for Linux. So far I am looking at Mondo, Systemimager, Partimage, and G4L.
Anyone with any preferences please post. So far I am leaning to systemimager. It is easy and reliable.
January 07, 2005
Tech article of the day
An interesting SSH Port Forwarding article.
January 05, 2005
Verifying distribution isos
December 21, 2004
How to install kernel source on Fedora Core 3
In the past, the process of updating the kernel did not change the default kernel in the system's boot loader configuration.
Fedora Core 3 changes this behavior to set newly-installed kernels as the default. This behavior applies to all installation methods (including rpm -i).
This behavior is controlled by two lines in the /etc/sysconfig/kernel file:
o
UPGRADEDEFAULT — Controls whether new kernels will be booted by default (default value: yes)
o
DEFAULTKERNEL — kernel RPMs whose names match this value will be booted by default (default value: depends on hardware configuration)
*
In order to eliminate the redundancy inherent in providing a separate package for the kernel source code when that source code already exists in the kernel's .src.rpm file, Fedora Core 3 no longer includes the kernel-source package. Users that require access to the kernel sources can find them in the kernel .src.rpm file. To create an exploded source tree from this file, perform the following steps (note that
1.
Obtain the kernel-
o
The SRPMS directory on the appropriate "SRPMS" CD iso image
o
The FTP site where you got the kernel package
o
By running the following command:
up2date --get-source kernel
2.
Install kernel-
3.
Change directory to /usr/src/redhat/SPECS/, and issue the following command:
rpmbuild -bp --target=
(Where
On a default RPM configuration, the kernel tree will be located in /usr/src/redhat/BUILD/.
4.
In resulting tree, the configurations for the specific kernels shipped in Fedora Core 3 are in the /configs/ directory. For example, the i686 SMP configuration file is named /configs/kernel-
cp
5.
Issue the following command:
make oldconfig
You can then proceed as usual.
http://fedora.redhat.com/docs/release-notes/fc3/x86_64/
Now to be honest, i"ve never seen up2date --get-source kernel work for the kernel, everything else it works but for some reason none of my box's work doing that, regardless you already have the .src.rpm and you have installed it. You can follow the rest thought.
cd /usr/src/redhat/SPECS
rpmbuild -bp kernel.spec
-bp Executes the "%prep" stage from the spec file. Normally this
involves unpacking the sources and applying any patches.
You can read "man rpmbuild" for more options.
-ba will build the binary and source package, ie. that is what people use after they create a spec file and build all the rpm/srpm(s) that are built in prereq's of the rpm.
Continue reading "How to install kernel source on Fedora Core 3" »
December 16, 2004
Xfce4 Goodies
Xfce is my lightweight desktop environment. I use KDE when I want full featured. Xfce goodies is a nice adjunct. It has lots of toys and fills gaps in the base Xfce installation.
Now and Xen
I have run across several stories of late about Xen. It is virtual machine software in a similar vein as Vmware. It doen't run Windows yet, due to license issues. It also appears to have much better performance than other VM software.
Hymn project information
From the web page:
The purpose of hymn is to allow you to exercise your fair-use rights under copyright law. It allows you to free your iTunes Music Store (protected AAC / m4p) purchases from their DRM restrictions with no sound quality loss. These songs can then be played outside of the iTunes environment, even on operating systems not supported by iTunes.
December 10, 2004
Using keychain to manage system logins
I have been using ssh key for system logins for awhile but I hadn't looked into using ssh-agent (ssh-agent bash or eval `ssh-agent` ) until recently. It has the drawback of needing one to run for each shell you have. A way around this is to use keychain. A good excerpt:
The idea behind keychain is simple: each user has a single perennial agent process instead of a per-session or per-login process.
keychain is a cross-platform shell script that can be included from any of your bash (or other sh-compatible shell) startup files. When executed, keychain starts an ssh-agent process running (if need be) or hooks into an existing ssh-agent. Once an ssh-agent is running, keychain loads all of your private keys into the agent.
With keychain you type your passphrase once and both ssh from an interactive shell and ssh from cron jobs are a painless experience.
December 01, 2004
ipcalc example
# ipcalc -h -m -p -n -b 64.236.24.4 255.255.248.0
NETMASK=255.255.248.0
PREFIX=21
BROADCAST=64.236.31.255
NETWORK=64.236.24.0
HOSTNAME=www1.cnn.com
November 22, 2004
Installing knoppix to your hard disk
A cool howto on installing knoppix to your system. I always keep a copy of 3.6 in my bag. you never know when you might need it.
Updated:
Another article on knoppix. This one on how to remaster a knoppix cd.
Another backup document
A good tutorial on using rsync for backups.
October 29, 2004
Log file mistakes
From Computerworld
A nice article that exposes the top five mistakes people make when watching log files for security issues.
No. 1: Not looking at the logs
No. 2: Storing logs for too short a time
No. 3: Not normalizing logs
No. 4: Failing to prioritize log records
No. 5: Looking for only the bad stuff
I find at a high level this would be true for watching for other things as well.
October 15, 2004
Recovering a lost root passwd
Linux Gazette has a helpful document on How to Reset forgotten Root passwords
Remember that as they say in this article:
Physical Access is Root Access. Meaning, if you give someone physical access to a system, then you are giving them a very good chance of getting root access on your box. This is true for Windows, Linux, or any other OS out there.
October 08, 2004
Linuxquestions wiki
October 07, 2004
How do I list my linux firewall rules.
Assuming you are running either iptable or ipchains run:
'iptables -L' or 'ipchains -L'
Does SuSE have anything like an /etc/rc.local?
/etc/init.d/boot.local plus my SuSE 9.1 distro also has boot.localfs and boot.localnet.
Nmap example
nmap -sS -p 22 -oG /tmp/test 17.0.0.0/8 &
This looks for hosts on the 17 network with port 22 open.
October 06, 2004
Guide to using live cd to repair system
Repairing your linux system was never easier. ;-)
September 13, 2004
LSB 2.0 released
From linuxbase.org
LSB 2.0 was released on August 30, 2004. This major new version adds Pthreads support, C++ support, a modular specification, alignment with current standards (Posix 1003.1-2001 / SUSv3) and a large number of quality improvements to the LSB
August 31, 2004
Cyrus links
http://anfi.homeunix.net/cyrus/
http://tomster.org/geek/freebsdcookbook/ar01s03.html
mtsend.py
A neat tool to give you a command line interface to Movable Type.
Curious
I hadn't really looked at Open-Xchange before. I knew it case with SLES, but I hadn't paid it much attention. I saw a news article that stated that it released an open source version so I checked it out. Here is there description:
The Open-Xchange Collaboration and Integration Server Environment allows you to store appointments, contacts, tasks, emails, bookmarks, documents and many more elements and share them with other users. This environment can be accessed via any modern web browser and multiple fat clients like KDE Kontact, Ximian Evolution (announced), Konqueror, Mozilla Calendar and many more. Every 3rd party product can access this application over many different interfaces like the WebDAV interface (XML), LDAP, iCal and HTTP(S). This makes the Open-Xchange application to a powerful product which can be used in many of different business and private areas.
Tuning your hard drive
USALug has a nice article on hdparm.
August 29, 2004
Linux dvd authoring links
http://www.nongnu.org/dvdrtools/
http://fy.chalmers.se/~appro/linux/DVD+RW/
http://qdvdauthor.sourceforge.net/
http://dvd-create.sourceforge.net/
http://www.dvdshrink.org/what.html
http://savannah.nongnu.org/projects/tkdvd/
http://lwn.net/Articles/98487/
http://crashrecovery.org/oss-dvd.html
http://crashrecovery.org/oss-dvd/HOWTO-ossdvd.html
August 17, 2004
August 12, 2004
How do I read proliant hardware logs from the command line?
If hpasm is running then run:
hplog -v
It should return errors when there are things like disk, fan, etc. failures.
How do I find the smtp relay server for a subdomain?
An example:
host -t MX rose.foo.com
Handy grub related links
July 30, 2004
qtparted
I just found out that there is a nice gui frontend to GNU parted. It is called qtparted.
July 12, 2004
Irc cheatsheet
An Irc Primer
July 11, 2004
False positives in chkrootkit
Checking `lkm'... You have 41 process hidden for readdir command
You have 41 process hidden for ps command
Warning: Possible LKM Trojan installed
./chkrootkit -x lkm
http://lists.samba.org/archive/linux/2004-March/010320.html
http://linux.cvf.net/installing_chkrootkit.html
There are some know false positives in chkrookit [1] and given the way it checks for some of the rookits it's bound to fail sometimes, also notice
that there are know issues with the latest kernel (2.6) and glibc (some processes will not show up no matter what). Also, nautilus and
mozilla-firebird seem to cause these false positives (as reported in bug #222179)
How do I change num lock on by default after boot?
From Linux tips"
When you boot Linux, the kernel turns off Num Lock by default. This isn't a problem if, for you, the numeric keypad is the no-man's-land between the cursor keys and the mouse. But if you're an accountant, or setting up a system for an accountant, you probably don't want to turn it on every single time.
Here's the easy way, if you're using KDE. Go to K --> Preferences --> Peripherals --> Keyboard and select the Advanced tab. Select the radio button of your choice under NumLock on KDE startup and click OK.
If you only run KDE and want Num Lock on when you start a KDE session, you're done.
Continue reading "How do I change num lock on by default after boot?" »
Resizing ext2 / ext3 filesystems
http://ext2resize.sourceforge.net/
http://linux.msede.com/ext2/
and of course resize2fs
Vnc for online classes
You can use vnc server if you're hosting a web conference or training class. Just tell the attendees to point their windows web browsers to http://hostname:5801
You can do -g 80% Rather than a specific geometry, it will just fill 80% of your screen.
July 01, 2004
Nice Screen (1) tutorial
I ran across a nice screen tutorial the other day. You can't beat screen for great session manager for terminal environments.
June 28, 2004
Naming conventions for RedHat Kernels
From otn.oracle.com of all places:
Upgrading from Red Hat Enterprise Linux 2.1 AS
To Red Hat Enterprise Linux 3
Author: Wim Coekaerts, Director of Linux Engineering
Date: January 2004
Numerous customers have started migrating from Red Hat Enterprise Linux 2.1 Advanced Server (RHAS2.1) to Red Hat Enterprise Linux 3 (RHEL3) or are deploying some new servers onto RHEL3 and have had several questions. Some of the known features have either changed behavior a little or have changed in naming or implementation. I will try to explain some of the more commonly used features of RHAS2.1 and how to make use of them in RHEL3.
In this technical note, I focus on the use of the Oracle VLM option to create a large database buffercache and on the use of hugetlb.
New Kernel Naming
RHAS2.1 for ia32
2.4.9-e.25—Uniprocessor kernel
2.4.9-e.25-smp—SMP kernel capable of handling up to 4GB of physical memory
2.4.9-e.25—enterprise-SMP kernel capable of handling up to about 16GB of physical memory
The userspace has access to about 3GB of the userspace segment; the kernel part lives in the other 1GB (4GB address space on 32-bit systems).
The default SGA can be up to 1.7GB (shared pool and buffercache). It is possible to create a larger SGA of up to 2.7GB, by using MAPPED_BASE and relinking the Oracle executable with a lower attach address.
RHEL3 for ia32
2.4.21-4.EL—Uniprocessor kernel
2.4.21-4.ELsmp—SMP kernel capable of handling up to 16GB of physical memory
2.4.21-4.ELhugemem—SMP kernel capable of handling beyond 16GB, up to 64GB
The other difference with the hugemem kernel is that the kernel and userspace address spaces are split 4GB/4GB, meaning that with the hugemem kernel, a userspace program has access to its 4GB.
With the smp kernel, the default SGA size is the same as in RHAS2.1. However, using the hugemem kernel allows you to create an SGA of up to 3.6GB without having to use the VLM option.
bigpages vs. hugetlb
A typical big server deployment in RHAS2.1 would use bigpages as a bootup parameter to preallocate a large chunk of memory to be used solely for shared memory. These pages have a 2MB or 4MB TLB entry that reduces the number of TLB misses and hence increases performance by a few percent.
The other advantage of using bigpages in RHAS2.1 was that it allowed the kernel VM not to worry too much about bookkeeping for that part of virtual memory. And these pages are not pageable or swappable, so one can guarantee that the Oracle SGA remains in main physical memory.
Enterprise Linux 3 has replaced bigpages with a feature called hugetlb, a backport of what is also in Linux kernel 2.6. There are a few differences in how hugetlb works. Hugetlb behavior is similar to that of bigpages; the pages are backed by large TLB entries, are not pageable, and are preallocated, which means that once you allocate x megabytes of hugetlb pages, that amount of physical memory can be used only through hugetlbfs or shm allocated with SHM_HUGETLB.
RHEL3 no longer requires a bootup parameter; it is dynamically adjustable. After the system has booted, you can echo a value to /proc/sys/vm/hugetlb_pool or you can put the value you want in /etc/sysctl.conf. The value is in megabytes, and it allocates several 2MB pages. You can see the values in /proc/meminfo:
Hugepages_Total: 500
Hugepages_Free: 500
Hugepagesize: 2048K
Note, however, that the kernel needs to find 2MB contiguous physical pages for allocating the hugetlb pool. It does its best to get as many pages as possible, but if there is a lot of fragmentation due to existing binaries running, the pool allocation will probably fail.
A program that wants to allocate shared memory has to add a flag, SHM_HUGETLB, to the shmget() flags. (Oracle Database 10g will do this by default; for Oracle9i Database, a patch is required.) This approach ensures that the Oracle shared memory segments will be allocated out of this pool.
VLM Option
For RHEL3 to use the VLM option to create a very large buffercache, you have two options:
* Use shmfs much as you would in RHAS2.1: mount a shmfs with a certain size to /dev/shm, and set the correct permissions. Keep in mind that in RHEL3, shmfs allocate memory is pageable.
* Use ramfs: ramfs is similar to shmfs, except that pages are not pageable/swappable. This approach provides the commonly desired effect. Ramfs is created by mount -t ramfs ramfs /dev/shm (unmount /dev/shm first). The only difference here is that the ramfs pages are not backed by big pages.
The parameter use_indirect_data_buffers=true remains the same; the settings on the Oracle side should not have to change.
June 21, 2004
Suse 9.1 mirrors and RH Transition service
June 16, 2004
More on enscript
We can control the margins with enscript as well.
enscript --no-header --fontFont --margin=7:7:21:21 --word-wrap
--fontFont is the name and size of the font to use. By default, GNU enscript uses 12 point Courier to format the file. You specify the font name and size like this: Courier10 (10 point Courier). GNU enscript can use any Postscript font on your system, but it's usually safe to stick with the following ones: Helvetica, Times-Roman, and Courier.
--margins=left:right:top:bottom
Adjust page marginals to be exact left, right, top and bottom PostScript points. Any of arguments can be left empty in which case the default value is used.
The man page enscript(1) has details on these and other options.
Changing font in cups with enscript
Because of changes to the texttops filter the Courier font is hardcoded for any mime type that uses that filter.
/etc/cups/mime.convs contains the following lines that show the mime types using this filter:
application/x-cshell application/postscript 33 texttops
application/x-perl application/postscript 33 texttops
application/x-shell application/postscript 33 texttops
text/plain application/postscript 33 texttops
text/html application/postscript 33 texttops
Create a file called "difffont" in /usr/lib/cups/filters and put this text in it:
#!/bin/sh
/usr/bin/enscript -B -f Courier-Bold10 $6
Make the script executable, and make sure it is owned by root. Replace Courier-Bold10 with the font you want to use. A list of available fonts is found in /usr/share/enscript/font.map
To print font.map in 14 point Palatino-Bold with no header lines:
enscript -B -f Palatino-Bold14 font.map
Then edit /etc/cups/mime.convs and replace "texttops" with "difffont" on the lines refering to the mime types you want to replace the texttopts filter.
Intro to lpoptions
http://www.cs.brown.edu/system/printing.html is a good starting place to using the cups command lpoptions.
You can set these values in ~/.lpoptions - for user defaults and instances created by non-root users or /etc/cups/lpoptions sets system-wide defaults.
For Example, In the file place the line :
You will have to experiment with the values of course.
June 15, 2004
Changing fonts in cups with enscript
Because of changes to the texttops filter the Courier font is hardcoded for any mime type that uses that filter.
/etc/cups/mime.convs contains the following lines that show the mime types using this filter:
application/x-cshell application/postscript 33 texttops
application/x-perl application/postscript 33 texttops
application/x-shell application/postscript 33 texttops
text/plain application/postscript 33 texttops
text/html application/postscript 33 texttops
Create a file called "difffont" in /usr/lib/cups/filters and put this text in it:
#!/bin/sh
/usr/bin/enscript -B -f Courier-Bold10 $6
Make the script executable, and that it is owned by root. Replace Courier-Bold10 with the font you want to use. A list of available fonts is found in /usr/share/enscript/font.map
To print font.map in 14 point Palatino-Bold with no header lines:
enscript -B -f Palatino-Bold14 font.map
Then edit /etc/cups/mime.conv and replace "texttops" with "difffont" on the lines refering to the mime types you want to replace the texttopts filter.
Alternative to disabling ACPI
Instead of completely disabling ACPI at boot time (with acpi=off), I only disable ACPI for PCI : the kernel boot parameter I use is pci=noacpi .
June 13, 2004
More rpm tips
To list the contents of an rpm package file you would run:
rpm -ql -p afile.rpm
The -p or --package tells rpm to look in afile.rpm rather than looking in the installed rpm database.
Adding the -p works for other query options as well.
Example:
# rpm -qlp cdrecord-ProDVD-2.01a27-1.i386.rpm
/usr/lib/xcdroast-0.98/bin/cdrecord-prodvd-2.01a27-i686-pc-linux-gnu
/usr/lib/xcdroast-0.98/bin/cdrecord-wrapper.sh
/usr/lib/xcdroast-0.98/bin/cdrecord.prodvd
/usr/lib/xcdroast-0.98/bin/prodvd
/usr/local/bin/cdrecord-ProDVD
/usr/local/bin/cdrecord-wrapper.sh
/usr/local/bin/prodvd
/usr/share/doc/cdrecord-ProDVD-2.01a27
/usr/share/doc/cdrecord-ProDVD-2.01a27/README.cdrecord-ProDVD.txt
/usr/share/doc/cdrecord-ProDVD-2.01a27/README.xcdroast-ProDVD.txt
February 03, 2004
new linux certification
A new certification from Novell/Suse. I now have LPIC level1. I need to decide if I want to do LPIC level 2, Redhat, or the Suse cert.
February 01, 2004
Kernel comparasion
January 28, 2004
troubleshooting nfs issues
Here are some tips to troubleshooting nfs perfomance / availability issues from the client:
rpcinfo -u
rpcinfo -t
nfsstat -c
January 27, 2004
Kernel level security mods
I think the three big projects around kernel-level security mods are LIDS, GRSecurity, and NSA SE Linux. Does anyone know of any others?
backing up mysql
/usr/local/bin/mysqldump --complete-insert --add-drop-table --lock-tables --user=USERNAME --password=PASSWORD DATABASE_NAME > FILENAME.sql
Replace USERNAME, PASSWORD, DATABASE_NAME, and FILENAME with the system specific values.
from http://www.mysql.com/doc/en/mysqldump.html:
shell> mysqldump [OPTIONS] database [tables]
OR mysqldump [OPTIONS] --databases [OPTIONS] DB1 [DB2 DB3...]
OR mysqldump [OPTIONS] --all-databases [OPTIONS]
... and ...
The most normal use of mysqldump is probably for making a backup of whole databases. See section 5.5.1 Database Backups.
mysqldump --opt database > backup-file.sql
You can read this back into MySQL with:
mysql database < backup-file.sql
or:
mysql -e "source /path-to-backup/backup-file.sql" database
However, it's also very useful to populate another MySQL server with information from a database:
mysqldump --opt database | mysql --host=remote-host -C database
It is possible to dump several databases with one command:
mysqldump --databases database1 [database2 ...] > my_databases.sql
If all the databases are wanted, one can use:
mysqldump --all-databases > all_databases.sql
January 22, 2004
eclipse ide rpms
I found precompiled binaries in rpm format for Eclipse. I am installing and testing them now. I run Fedora Core 1 these days.
Update: I had to install three packages to get Eclipse to install:
error: Failed dependencies:
ctags is needed by eclipse-2.1.0-12
libgcj-ssa is needed by eclipse-2.1.0-12
oprofile >= 0.5 is needed by eclipse-2.1.0-12
ctags and oprofile are easily installable from rpmfind.net. libgcj-ssa I found at http://mirror.dulug.duke.edu/pub/fedora/linux/core/development/i386/Fedora/RPMS/
January 14, 2004
Tech talk
I spoke to the Atlanta Unix Users Group last week. It went well. There was a good crowd, and lots of questions. My topic was Samba/CIFS installing, configuring, and troubleshooting. This is the same paper I gave at hpworld. I somehow lost the presentation and had to recreate it.
torrent to get fedora core 1 dvd iso image
http://torrent.dulug.duke.edu/
rpmdb repair FAQ
I have been bit by rpm hangs intermittently. Typically the answer I had always used was to run:
rm -f /var/lib/rpm/__db*
rpm -vv --rebuilddb
This faq from rpm.org deals with it in a less intrusive way.
Mutt Cheatsheet
Both index and pager allow you to perform common mail operations - delete, forward, reply, save - and use standard keys for navigation. Here's a quick list of the default navigation keys (you can change these if they don't work for you, keep reading for details):
Key What it does Where it does it
---------------------------------------------------------
j Move one line up Index
k Move one line down Index
z Move one page up Index
Z Move one page down Index
Open message Index
- Move one page up Pager
Move one page down Pager
q Close message Pager
In addition to these navigation keys, Mutt also allows you to perform commonly-used functions just by tapping the appropriate key. Here's what you need to get started:
Key What it does Where it does it
---------------------------------------------------------
m Compose new message Index, pager
r Reply to current message Index, pager
f Forward current message Index, pager
d Delete current message Index, pager
b Bounce current message Index, pager
c View different mailbox Index, pager
v View attachment Index, pager
a Create alias Index, pager
q Quit Index, pager
You can obtain a complete list from the Mutt manual, or by tapping the
You already know that the
a
key is used to capture email addresses and create aliases for them. You can specify the location of the file which stores these aliases:
Note, however, that I can still view the complete headers of any message by hitting
h
in the pager.
You can customize the message display in the index with the "index_format" variable, which allows you to specify which elements to display in each message index line. The default setting is
set index_format="%4C %Z %{%b %d} %-15.15L (%4l) %s" # format index
which translates to
set index_format="number status date sender lines subject"
Want a no-frills version? This one only displays the date, sender and subject:
set index_format="%{%b %d} %F (%s)" # format index
November 14, 2003
YAL. Is this really needed
Is another linux distro. needed? I am not sure this is a good thing. I know RedHat specifically has irritated the opensource community, but firther splintering is not good. I would like to know if this will be a fork of Debian or if it will ride on top.