Diffing files via FTP

Tags: diff, ftp

I ran into a situation today where I needed to diff files on a remote server against the ones on a local server when the only connection method I had to connect to the remote server was FTP. I wrote a little quick and dirty script to diff files over FTP. It’s stupid simple – it downloads the file and runs diff on it against a local file, outputting the result.

It’s great for finding changes on a webhost that cripples real developers by only offering FTP. It’s also a great companion to ftpsync, which apes some of the functionality of rsync, again on crippled webhosts.

The command format is:

ftpdiff <local file> <username:password@host:/path/to/file>

ngrep and memcache

Tags: linux, php, memcache, ngrep

You can use the Linux command ngrep to "watch" what is going into and coming out of memcache. ngrep is an amazingly useful tool for troubleshooting a wide array of network issues; I previously have used it extensively for troubleshooting SIP errors. In this case, I’m using it to be sure memache sessions in PHP are actually working.

codelemur ~ # ngrep -d lo port 11211
interface: lo (127.0.0.0/255.0.0.0)
filter: (ip) and ( port 11211 )
####
T 127.0.0.1:60912 -> 127.0.0.1:11211 [AP]
get a804f5517468d4696c60da7eaf8a7179..
##
T 127.0.0.1:11211 -> 127.0.0.1:60912 [AP]
VALUE a804f5517468d4696c60da7eaf8a7179 0 16..test|s:4:"test";..END..
##
T 127.0.0.1:60912 -> 127.0.0.1:11211 [AP]
set a804f5517468d4696c60da7eaf8a7179 0 1440 16..test|s:4:"test";..
#
T 127.0.0.1:11211 -> 127.0.0.1:60912 [AP]
STORED..

It doesn’t help too much if you have multiple memcache servers (which is kinda the point of memcache), and since it’s raw data you can’t inspect the packets if they’re compressed, but in a testing environment, it’s a great way to be sure all things are kosher.

Ubuntu 8.04: My Thoughts

Tags: linux, ubuntu

Every so often I get the urge to check out desktop Linux – just to see how things have progressed and whether or not it is in a usable state yet. For the last few times, the distro of choice I have tried has been Ubuntu, as that seems to be the new de facto starting point for a desktop distro.

Before beginning this review, let me first say that desktop distros have come a long way over the last few years, and Ubuntu is by far the most usable of the ones I’ve seen. Ubuntu itself has come a long way and, for someone who is willing to compromise on some points, is quite usable for someone who’s willing to spend some time tweaking things.

Having said that, it still has a ways to go before reaching Windows. And it’s not even in the same league as Mac OS X.

First, a little about my test rig: An AMD Athlon64 3700+ with 2 gigabytes of memory, two 250gb SATA hard drives (one for Windows, one for whatever OS I’m testing at the time), and dual GeForce 7600 GS’s running three 19″ Samsung LCDs. Not your standard setup, mind you, but not ultra advanced and bleeding edge, either.

The installation: The installation is much the same as previous releases of Ubuntu: load up the live CD and, from within the live environment, launch the installer. The installer itself asks fewer questions that the Windows XP installer, yet seems to be able to do more. And doesn’t require endless reboots to get everything working.

My installation proceeded mostly okay (being that Windows resides on sda, I installed Ubuntu in sdb), except that after I installed and rebooted … nothing. It kept booting into Windows. I reinstalled again just to be sure I didn’t blitz through the boot record screen, but sure enough, writing to the MBR on sda doesn’t work when you have two SATA drives and you’re installing Ubuntu on sdb. This has been a bug for at least the last two times I’ve tried to install Ubuntu. I can fix it with grub commands and properly write a boot record to sda, but for the purposes of testing (and because I’m lazy and wanted to play with it) I just plugged sdb directly in and removed sda. So I’m up and running. This is something that would befuddle a lot of folks, but to be fair I’ve had problems with Windows in the past, but it seems like it would be an easy fix.

So I have Ubuntu installed now. Yay. Next step is to get my three LCDs working. This is where we run into what I think is the biggest hinderance to desktop Linux: X.

If I plug three monitors into two video cards on a Mac, it’s going to turn on all three monitors and allow me to drag things between them all effortlessly (one big desktop). If I plug it into Windows, I’ll need to download the drivers, but after that, no problems. Not so in X, though in fairness it is likely more due to the intrangisence of Nvidia when it comes to providing open source support.

First, if you want to do anthing, you have to download a “Restricted” driver. This is Ubuntu-speak for “we didn’t want to compromise our oh-so-precious ‘free‘ principles in the name of usability” (in case you can’t tell, I have very little patience for zealotry). In Ubuntu 8.04, the Restricted Drivers Manager has been poorly renamed to Hardware Drivers. Doesn’t make a lot of sense, since a driver for hardware may or may not be restricted. So, I download and install the Nvidia drivers.

Next, fire up the nvidia-settings utility to fix the X config. I was running this from the shell, but I later discovered that it puts a nice menu item in the Administration for you. It sees all my cards and, using this, I am able to configure everything up.

You have multiple options for ways to do three monitors, but only one works: Xinerama. You could do three separate X screens, but you can’t move windows between them. You could do Twinview on one screen and a separate X screen but, again, you couldn’t move windows between a dual screen and the third monitor, the windows on the Twinview screen don’t maximize and minimize properly, and the login screen is right in the middle of the two monitors so that it’s very difficult to see what you’re tying when you login. Only Xinerama lets you move windows between the three monitors, allows them to maximize properly, and has the login on a single screen. This was about an hour of changing settings and restarting X before I got it right.

The downside? It still isn’t supported in Compiz, which is a real bummer becauase compositing window managers was one of the things I was really looking forward to using. Anybody know if Compiz accepts bounties, because I really want this feature?

So no Compiz. Oh well. Next, get my other hardware working. I have a Logitech MX1000 Laser (greatest mouse ever, by the way), and I like to map the buttons to do various things (most notably, I use the “cruise” buttons to go back and fourth on web pages). In order to get this to work:

1. sudo apt-get install xserver-xorg-input-evdev
2. cat /proc/bus/input/devices (find Logitech USB Receiver)
3. sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.bak
4. sudo gedit /etc/X11/xorg.conf
5. Changes:

Section "InputDevice"
Identifier "Configured Mouse"
Driver "evdev"
Option "CorePointer"
Option "Name" "Logitech USB Receiver" #this should be the name of the device which I made bold here.
EndSection

1. sudo apt-get install xvkbd xbindkeys
2. gedit ~/.xbindkeysrc
3. Changes:

"/usr/bin/xvkbd -xsendevent -text "\[Alt_L]\[Left]""
m:0x0 + b:12
"/usr/bin/xvkbd -xsendevent -text "\[Alt_L]\[Right]""
m:0x0 + b:11

After restarting (yes, again) I have working buttons. Yay.

The volume control on my Microsoft Natural Egro 4000 works now. It seems like this required some hacking last time around. Yay.

Now to install some developer tools so I can get to work. I love Synaptic; I wish Mac OS X had real package management the way Linux does – it’s one of the things Linux really has going for it, though I generally prefer Gentoo’s portage manager. So I install Eclipse. Huge package, and I was getting really crappy download speeds, so I let it run all night and went to bed. The next day found Eclipse installed and ready to go. Installed PHP, SVN, Apache. So I now have the tools to work.

My conclusions: I like Linux. I really do. I want to see Linux succeed on the desktop. And Ubuntu has gone further, faster than any other Linux distro. It is now by far the most fit and ready to use of any desktop Linux distro. I have a usable system now, and, theoretically, there is nothing stopping me from using my machine for most of my daily work.

Having said that, there is a lot to be said for style. First of all, it’s ugly as sin. The Gnome UI, while it is much improved, is still terrible when compared to Windows and OS X. Also, who thought that brown was a good color for a UI? Second, the names of some of the tools are un-intuitive: “Hardware Drivers,” “SCIM Input Method Detection,” “Authorizations,” and others need to have more intuitive names, and once you use any of them, the layout is not really intuitive either. The initial screen layout with a menu at the top and a taskbar at the bottom is also not really all that usable, though it can be corrected by removing the top panel.

I’m using it now (typing this in Drivel) so it is usable, but it still can’t displace my Mac for ease of use.

Gentoo

Tags: linux, gentoo

I’ve been a happy Gentoo user for the last few years. There’s so much to like about it: built from source with only what you need and Portage beats the pants off RPM, among many other reasons. But lately, I’ve been getting a little annoyed with it.

My annoyance has to do with the releases … or lack thereof. And, the communication about said "delays" … or lack thereof.

There used to be four Gentoo releases a year. A few years ago, they went to two releases a year. Last year, they completely skipped 2007.1 release. Now, we’re three months into 2008 and the 2008.0 release, which was supposed to be released to the public as stable on March 17th, hasn’t even been seeded to mirrors for public beta yet. 2007.0 is still the official stable release of Gentoo – a release that is more than a year old at this point.

This wouldn’t be a big deal if I didn’t really need an updated live CD to do installs with. I have new machines with an onboard SATA controller that isn’t supported by the kernel in the 2007.0 release but is supported by the 2.6.23 kernel which was in the Gentoo sources at the time. I was at an impasse, unable to install Gentoo on my equipment until I got around it by compiling my own updated kernel and rolling my own live CD. But, I wouldn’t have had to do that if the Gentoo release team could at least come close to hitting their release schedule. I’m not asking for the universe – just get within the same month as the schedule says and we’ll call it good.

There’s also been disturbingly little communication about the reasoning behind these "delays." There was one post to the site about the 2007.1 release being cancelled. There’s been no communication on the site whatsoever about the delay with 2008.0. The things on the front page right now talk about the monthly newsletter and some new trustees of the Gentoo foundation.

I know it’s free software and I shouldn’t complain, but for those of us who make our living using Gentoo, it’s a bit annoying to say the least. You won’t need trustees of a foundation if there’s no foundation … because everyone goes somewhere else because the distro is updated less often than a phone book comes out.

PHP, PostScript and ATM Fonts

Tags: pecl, php, postscript, linux, gentoo

Recently, I’ve been expermenting with PHP’s PS functions – the PECL extension that allows you to directly output PostScript from your scripts. There are other projects that come to mind (html2ps is another one that will render to PostScript) but I wanted somsething more tightly intergrated into my script.

Mysteriously, when I went to install my scripts on the new Poweredge I bought, I began to get there strange errrors:

ps_findfont() [function.ps-findfont]: PSlib warning: Trying to insert the glyph ‘.notdef’ which already exists. Please check your afm file for duplicate glyph names.

I couldn’t understand what was going on – it was working fine on the previous server. After googling about the web and wracking my brains for about two hours, I checked the versions of PSlib  installed on the two servers. Both were masked by Gentoo’s Portage system, but the unmasked version on the previous server was 0.2.6, whereas the one on the new server was 0.4.1. After I masked out 0.4.1 (thanks to Gentoo’s awesome package.mask) and downgraded back to 0.2.6, everything began working again.

So there you have it. Apparently the PECL PS extension is not completely compatible with the most recent version of PSlib, and downgrading back seems to work. Hope this helps somebody!