I use grep a lot. Today I realized that others might not know that GNU grep can highlight matches, or how to combine it with less. So here's part of my Bash config, and some examples uses:
alias grep='grep --color=auto'
alias egrep='egrep --color=auto'
function legrep {
egrep --color=yes "$@" | less -R
}
$ legrep '[Gg]nome' */*.xml $ legrep -i foo /usr/share/dict/words $ grep bar | egrep -v 'baz|qux' | legrep bar
SUSE has long used YaST as a management tool. It makes it easy to make changes to your system without knowing (or caring) what happens behind the scenes.
At Guru Labs, our Linux Training is all about teaching students what happens "behind the scenes". We strive to document the official and best practice techniques (not always the same thing, unfortunately).
Recently we were updating our courseware and wanted to document how to disable IPv6 in the various Enterprise Linux distributions. The question came up, "What does YaST actually do when you toggle the Enable/Disable IPv6 checkbox in the YaST network module." To answer that question I performed the following steps on SLES11.
Search for the string IPv6 in the YaST network module.
grep -n IPv6 $(rpm -ql yast2-network)
In the output, found these lines looked interesting (Note the Disable/Enable strings)
/usr/share/YaST2/modules/Lan.ycp:316:global void SetIPv6(boolean status){
/usr/share/YaST2/modules/Lan.ycp:324:void writeIPv6(){
/usr/share/YaST2/modules/Lan.ycp:424: writeIPv6();
/usr/share/YaST2/modules/Lan.ycp:654: status_v6 = _("Support for IPv6 protocol is enabled");
/usr/share/YaST2/modules/Lan.ycp:656: link_v6 = Hyperlink (href_v6, _("Disable IPv6"));
/usr/share/YaST2/modules/Lan.ycp:662: status_v6 = _("Support for IPv6 protocol is disabled");
/usr/share/YaST2/modules/Lan.ycp:664: link_v6 = Hyperlink (href_v6, _("Enable IPv6"));
Based on my experience I guessed that the writeIPv6 function does the work of enabling and disabling IPv6 on the system.
So I took a look at that function using the line number found by grep:
vim /usr/share/YaST2/modules/Lan.ycp +324
I found the following:
void writeIPv6(){
SCR::Write(.target.string, "/etc/modprobe.d/ipv6", sformat("%1install ipv6 /bin/true", ipv6?"#":""));
SCR::Write(.sysconfig.windowmanager.KDE_USE_IPV6, ipv6?"yes":"no");
}
That pointed me at the two files "/etc/modprobe.d/ipv6" and "/etc/sysconfig/windowmanger".
Looking at the files it seems YaST simply removes/adds the comment character in front of the one-and-only line in the file /etc/modprobe.d/ipv6 and it toggles the variable KDE_USE_IPV6 in /etc/sysconfg/windowmanager.
If you ever have the need to discover what YaST is doing behind the scenes, you can use the same technique.
As far as blogging software goes, it's hard to go wrong with Movable Type. It is open source, supports PostgreSQL (unfortunately, due to be dropped in MT5.0, hopefully it will be re-added in 5.1), supports multiple users and blogs out of the box, can operate in static, partial-dynamic, and full dynamic mode.
If for some reason you or a user forgets their password you can reset the password via the following SQL commands
PostgreSQL
Make sure to install the postgresql-contrib package if you don't already have it installed.
Install the crypto functions into the Movable Type database, this is a one time task.
psql -d movabletype -f /usr/share/pgsql/contrib/pgcrypto.sql
Now connect to the movabletype database and run the following command to reset a password:
UPDATE mt_author SET author_password = crypt('the-new-password', gen_salt('des')) WHERE author_name = 'USERNAME-GOES-HERE';
MySQL
The MySQL database already has the crypto functions built-in, so reset the password with the following SQL statement:
UPDATE mt_author SET author_password = encrypt('the-new-password') WHERE author_name = 'USERNAME-GOES-HERE';
Tools available with Fedora and Red Hat Enterprise Linux for converting CDs to lossless FLAC archives include Sound Juicer, Rhythmbox, and the command line tool abcde. The first two are graphical applications in GNOME that use MusicBrainz for metadata; the latter provides numerous options for converting to FLAC, Vorbis, and MP3 (among other formats), using CDDB for metadata. I wanted something simpler, resulting in a minimal set of metadata (consistent with ID3), and following a stricter Unix model of each tool focused on one job, doing that job well.
The result, flaccda, is a POSIX compliant script for converting CDs to FLAC, and a supporting script for removing MusicBrainz metadata from FLAC archives created by tools such as Sound Juicer.
The source may be downloaded from my website at http://deevans.net/hacking/flaccda.
I noticed in the list of Common Fedora 12 Bugs that in order to run the current version of Adobe Acroread for Linux it must be launched with:
GDK_NATIVE_WINDOWS=1 acroread
Note that GDK is the underlying graphical toolkit for creating GUI applications using GTK (most commonly for applications used on the GNOME desktop). The Linux version of Adobe Acroread uses GTK/GDK.
I was curious about GDK_NATIVE_WINDOWS=1 and I found the following information:
From www.gtk.org I found
GDK has been rewritten to use 'client-side windows'. This means that GDK maintains its own window hierarchy and only uses X windows where it is necessary or explicitly requested. Some of the benefits of this change are
- Reduced flicker
- The ability to do transformed and animated rendering of widgets
- Easier embedding of GTK+ widgets, e.g. into Clutter scene graphs
Launching an app with GDK_NATIVE_WINDOWS=1 application turns off this feature. This is needed if the application manipulates the windows it creates using direct X API calls or a mixture of X API and GDK instead of just going through GDK. When using "client-side windows" all window manipulation by an application must go through GDK. Adobe needs to update Acroread to be compatible with this feature.
Here is a video demonstration from Alexander Larsson showing some of the effects made possible with 'client-side-windows'. You can also check out his blog post The return of client side windows:
The official documentation on ClientSideWindows is here.
I've been having a problem with the back light on my T61p (T7500), after a text terminal (runlevel 3) screen blank (stand by, not suspend?), running Fedora 11. After logging off, the text terminal screen goes blank as a power saving feature. However, upon restore the backlight setting is one fifth full luminosity.
After a bit of digging, the acpitool manual claims it can update the brightness setting (with -l x) using the /proc/acpi/ibm/brightness file. However, the file doesn't exist. I did find the brightness file under /proc/acpi/video/VID1/LCD0/. A redirect of the highest setting restores luminosity (the setting is 1 through 100; after the screen blank it had gone down to 28): echo 100 > /proc/acpi/video/VID1/LCD0/brightness
The last problem is one of persistence. For the time being, I've not found a solution. Fedora seems to have made the assumption that GNOME or KDE is all anyone uses.
My Lenovo Thinkpad T61p died today, but I'm still in a good mood. I've never had such a positive experience calling any company's support line before.
Finding the phone number for Lenovo was a bit of a hassle, but everything else was painless. I spent less than two minutes in the call queue before talking to a human being. Lenovo was careful to mention several times that they were transferring me to their Georgia call center. The cynical might suspect they meant the eastern European nation, but I'm inclined to believe it really was the state. The person I spoke with had an American accent and understood everything I said. He wasn't blindly following a script, but actually listened to what I said and responded appropriately. Within a minute he had decided to replace the entire mainboard. No hassle!
I've recommended Lenovo before because of the quality of the Thinkpad. Now I can add the amazing support. IBM's hand off to Lenovo scared me a little, but they seem to be doing an excellent job. Let's hope it stays that way.
I have a ThinkPad T61p Fedora 11 Linux laptop. Lately for some Linux training products we have been developing I've been doing alot of virtualization work on my laptop. Even though it has a fast dual core CPU, 8GB of RAM, and a fast internal 500GB SATA hard drive I've been seriously bottlenecked when I have a bunch of virtual machines doing lots of I/O. Some operations that normally take 20 minutes to complete have been taking 90 minutes. That is a serious productivity killer.
I need to add more hard drives and spread the I/O load across them. I would like to upgrade to a SSD drive, but I require 500GB capacity and although the just hit the market, it has several draw backs (besides the price) including using a MLC architecture. I briefly considered USB 2.0 hard drives but I knew that the USB 2.0 connection was a bottleneck
I decided to add an external eSATA hard drive using an ExpressCard eSATA controller.
Here are raw sequential I/O throughput the benchmark numbers on three drives. I tested the performance using hdparm -tT /dev/{sda,sdb,sdc}
Internal SATA SAMSUNG HM500LI 500GB
73.4 MB/sec
eSATA Western Digital WD10EVVS-63E 1TB "My DVR Expander"
85.1 MB/sec
USB 2.0 Lacie 120GB rugged
24.4 MB/sec
I used a Syba SD-PCBX-ESA2 ExpressCard SIL3132 Chipset 2x e-SATA II, 54mm
It would have been nice if my laptop had a built-in eSATA port. Hopefully my next Calpella platform based Thinkpad will have bottleneck free USB 3.0 ports and hopefully eSATA as well.
I've been running Fedora 11 on my T61p laptop, and I recently ran into the bug that caused repeated kernel oopes when running a NFS server and serving a bunch of data.
This bug has been fixed with the F11 kernel 2.6.29.6-213.fc11 which (as of July 9th, 2009) hasn't been pushed out yet (it is currently pending for fedora-updates-testing). I installed the new kernel and it has fixed the bug. Hurray for progress.
Unfortunately the yak shaving continues. I'm using RPM Fusion to get drivers for my Nvidia video card in my laptop. Since I'm running an unreleased kernel, the RPM Fusion repo doesn't have a matching kmod-nvidia package for the kernel portion of the Nvidia driver. My system automatically reverted to the VESA driver. Having the Nvidia libraries installed while using the VESA driver caused Unexpected signal: 11 problems for VMware workstation.
In order to build a matching kmod-nvidia package I performed the following (note I'm running 64bit Linux).
# yum install -y buildsys-build-rpmfusion-kerneldevpkgs-newest-x86_64
Now install the kernel-devel package for the newer kernel. I downloaded it from the Koji web page and manually installed it with rpm -ivh.
Download the newest nvidia-kmod.src.rpm from http://download1.rpmfusion.org/nonfree/fedora/updates/11/SRPMS/. Adjust the URL as needed for your version of Fedora.
Then, the command to rebuild the binary RPM that matches your running kernel is.
$ rpmbuild --rebuild nvidia-kmod-VERSIONINFO.src.rpm --define "kernels $(uname -r)" --target $(uname -m)
In my particular case it was:
$ rpmbuild --rebuild nvidia-kmod-185.18.14-1.fc11.1.src.rpm --define "kernels $(uname -r)" --target $(uname -m)
At Guru Labs we've been long time smartphone users. I purchased a Treo 600 in October of 2003 and have had pretty much all the Treo revisions since then.
Having a smartphone is extremely handy for in my line of work (traveling and doing Linux training). The original PalmOS has gotten pretty dated and I admit I've had some iPhone envy the last couple years. Lack of multi-tasking, Apple control issues, AT&T, and no real keyboard has kept my envy at bay. Ever since Palm announced that they'd have a Linux powered Treo back in 2004 I've been patiently waiting.
Finally, after 5 years of waiting, I have a Linux powered Palm smartphone! I've had the Palm Pre running webOS for the past few days.
This phone is awesome. Highly recommended.
If you are the tinkering type of person and don't mind potentially having to do a factory restore on your device (which isn't so bad given that you can easily restore your settings and data via your Palm Profile) you might want to:
1. Gain root access on your phone via "Developer Mode".
2. Install a SSH backdoor door ongoing access (a procedure to which I contributed a great deal)
Palm webOS is a fairly typical Linux distribution. Here is data from version 1.0.2 (As of June 11th 2009).
root@castle:/etc# lsmod
Module Size Used by
sd8xxx 184732 1
bridgedriver 187924 1
g_composite 99292 0
root@castle:/etc# **cat palm-build-info **
PRODUCT_VERSION_STRING=Palm webOS 1.0.2
BUILDNAME=Nova-Sprint-Castle
BUILDNUMBER=118
BUILDSET=base
BUILDTIME=20090522140049
BUILDMARK=165841
root@castle:/etc# **cat issue.net **
Rockhopper .dev-snapshot-20090522 %h
eth0 Link encap:Ethernet HWaddr 00:1D:FE:XX:XX:XX
inet addr:10.2.3.203 Bcast:10.2.3.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:3106 errors:0 dropped:0 overruns:0 frame:0
TX packets:2282 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:315417 (308.0 KiB) TX bytes:677358 (661.4 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:3580 errors:0 dropped:0 overruns:0 frame:0
TX packets:3580 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:294062 (287.1 KiB) TX bytes:294062 (287.1 KiB)
ppp0 Link encap:Point-to-Point Protocol
inet addr:174.149.231.221 P-t-P:66.174.200.5 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1480 Metric:1
RX packets:3428 errors:5 dropped:0 overruns:0 frame:0
TX packets:4745 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:1746157 (1.6 MiB) TX bytes:3258322 (3.1 MiB)
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 14456 packets, 4914K bytes)
pkts bytes target prot opt in out source destination
Chain ALLOWED_PACKETS (15 references)
pkts bytes target prot opt in out source destination
9211 3590K ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0
Chain ICMPFLOOD (1 references)
pkts bytes target prot opt in out source destination
4 324 all -- * * 0.0.0.0/0 0.0.0.0/0 recent: SET name: ICMP side: source
0 0 LOG all -- * * 0.0.0.0/0 0.0.0.0/0 recent: UPDATE seconds: 1 hit_count: 6 TTL-Match name: ICMP side: source limit: avg 1/sec burst 1 LOG flags 0 level 4 prefix `IPT_ICMPFLOOD: '
0 0 DROP all -- * * 0.0.0.0/0 0.0.0.0/0 recent: UPDATE seconds: 1 hit_count: 6 TTL-Match name: ICMP side: source
4 324 ALLOWED_PACKETS all -- * * 0.0.0.0/0 0.0.0.0/0
Chain INVALID_PACKETS (1 references)
pkts bytes target prot opt in out source destination
0 0 LOG all -- * * 0.0.0.0/0 0.0.0.0/0 limit: avg 1/sec burst 100 LOG flags 0 level 4 prefix `IPT_INVALID_PACKETS_DROPPED: '
0 0 DROP all -- * * 0.0.0.0/0 0.0.0.0/0
It’s time for me to praise one of the useful utilities that makes my everyday work just a little bit more pleasant: rlwrap.
rlwrap “wraps” other interactive programs, providing readline functionality for programs that don’t have it built in. For example, last week I had to repeatedly use ‘imtest’ and ‘cyradm’ while doing some exploration about IMAP. Neither of these tools supports readline, so I normally would be able to press ‘up’ to recall my last command, use ^W or ^U to clear parts of my command, or use ^R to search my history. This would be very frustrating.
So, here comes rlwrap. You use it just like sudo, prefixing it to the command you want to run, thus
imtest -u sweeks -a vmadmin -t '' -m plain localhost
becomes
rlwrap imtest -u sweeks -a vmadmin -t '' -m plain localhost
rlwrap even remembers command history on a per-command basis, so you can recall your interactive commands from previous sessions. This greatly eases debugging. rlwrap is a very valuable part of my toolkit. If this interests you, you can also enable filename tab-completion, or even custom wordlists for tab-completion of command-specific commands.
I mentioned this to my co-workers, and I was surprised to hear that none of them had ever heard of it before. What tools do you use that you take for granted that everybody knows about?
On Saturday, I wrote up a possible API for Parrot compilers to support loading libraries written in other languages and discussed some of the details with Jonathan++ and Allison++. It’s not perfect, and is missing a few parts, but should be extensible enough to support whatever else we need in the future. I still need to formalize it a bit and add it to the Parrot docs and the example language shell.
On Sunday, I implemented it on Rakudo (Perl 6) and Cardinal (Ruby; very incomplete).
This morning, after confirming the spec with pmicahud++, I merged the changes into Rakudo trunk.
The syntax for specifying the source language for Perl 6 is:
use Foo:lang<cardinal>;
I couldn’t quite figure out what an appropriate way to do this in Ruby would be, so I just added a function to cardinal:
foreign_load('perl6','Foo/Bar')
If you have a better suggestion for what it should look like in Ruby, please let me know! I don’t actually know much Ruby at all, so my Ruby compiler is fairly limited.
I’ll be adding support for this to pynie (Python) soon, and other languages after that.
Here’s a simple example of using a Perl library from Ruby:
[sweeks@kweh ~]$ cat Foo.pm
module Foo {
sub greet($name) is export {
say "Hello, $name!"
}
}
[sweeks@kweh ~]$ cat perl6.rb
foreign_load 'perl6', 'Foo'
['Ruby', 'Perl', 'World'].each { |name| greet name }
[sweeks@kweh ~]$ cardinal perl6.rb
Hello, Ruby!
Hello, Perl!
Hello, World!
Here’s a similar example of using a Ruby library from Perl:
[sweeks@kweh ~]$ cat Foo.rb
module Foo
def greet(name)
puts "hello, " + name
end
def apply_people(cb)
people = ['Dave', 'Bryan', 'Stuart', 'Dax']
people.each { |name| cb(name) }
end
end
[sweeks@kweh ~]$ cat ruby.pl
use Foo:lang<cardinal>;
greet("person $_") for 1..5;
apply_people( { say "hello from perl, $^name" } )
[sweeks@kweh ~]$ perl6 ruby.pl
hello, person 1
hello, person 2
hello, person 3
hello, person 4
hello, person 5
hello from perl, Dave
hello from perl, Bryan
hello from perl, Stuart
hello from perl, Dax
Thanks go to my employer (Guru Labs) for their support in my work on Rakudo and Parrot.
Rakudo is just starting to get support for adding custom operators to the grammar from user-level code. You can’t specify the precedence yet, but you can run the traditional examples:
multi sub infix:<±>(Int $a, Int $b) { return $a + $b | $a - $b }
multi sub postfix:<!>(Int $a where { $_ > 0 }) { return [*] 1..$a }
my $x = 5! ± 2;
say "hi dood" if $x > 121;
say "hello again" if $x < 119;
I was playing around today with defining operators for mathematical set operations (∩ ∪ ∖ ⊂ ⊃ ⊆ ⊇ etc.) and then decided that I wanted a fancy syntax for defining sets, so I added support to rakudo for circumfix operator definition, and i now have this running on rakudo:
say "subset" if ⦃ 1, 3, 5 ⦄ ⊆ ⦃ 1, 2, 3, 4, 5 ⦄;
Aggregated Blogs:
Aaron Toponce
Almost Everything Linux
Bryan's Blog
Dax's Blog
D. E. Evans
goozbach's Techtips
Mike
Stephen Weeks
Stuart's Blog
Tim - the *other* archlinux user