Special device UUID does not exist
Wednesday, 09 May 2012 20:30
Q. I'm trying to mount a drive using UUID, but I get the following error:
mount: special device /dev/disk/by-uuid/87470c42-4b34-475c-86d0-bf0df06d4f3c does not exist
A. You've just created the new partition and the OS doesn't see it. You can either reboot or run the following command
sudo partprobe
Convert SSL certificate from CRT format to PEM
Tuesday, 08 May 2012 12:23
Q. Ubuntu 8.04 is setup by default to accept PEM certificates instead of CRT, is there any way to convert it?
A. You can convert the SSL certificates using the following commands:
openssl x509 -in server.crt -out server.der -outform DER
and:
openssl x509 -in server.der -inform DER -out server.pem -outform PEM
Measure disk I/O in Ubuntu
Monday, 30 April 2012 12:05
Q. I think I'm having disk I/O problems on my system. How do I check what it is or measure it?
A. First, you'll have to install some applications/tools:
apt-get install sysstat
apt-get install iotop
iotop command, much like top, will give you the real-time overview of your Read/Write requests. It's fun to look at, but we find useless for measuring I/O.
Enable Internet Explorer in Windows 2008 Server
Tuesday, 17 April 2012 15:12
Q. How can I disable all those warning in Internet Explorer on my server and just the browser?
A. You have to disable Internet Explorer Enhanced Security Configuration (IE ESC).
1. To do that, go to Start -> Administrative Tools -> Server Manager
Change access permissions in command prompt
Thursday, 29 March 2012 07:02
Q. 
I'm logged in as a non-privileged user and would like to change file permissions. How do I do that without logging out?
A. 1. First you have to open the command prompt as a privileged user. That can be found under Start -> "All Programs" -> Accessories. Right-click on the "Command prompt" icon and select "Run-As".
2. Once prompted, enter username and password.
3. On the command line, you can use a comman called CACLS. Here's the full list of things that it can do:
Parsing Apache access log files using PHP
Friday, 24 February 2012 13:34
This is a bit dated, but I still come back to it. A small script (using regex) that parses apache log files. The data breakdown required:
IP ADDRESS - -
Server Date / Time [SPACE]
"GET /path/to/page
HTTP/Type Request"
Success Code
Bytes Sent To Client
Referer
Client Software
Exchange 2010 Error: Unable to mount database
Tuesday, 20 December 2011 09:34
Q. My Exchange server crashed and I'm trying to mount the database, with no luck.
This is the error that I get:
--------------------------------------------------------
Microsoft Exchange Error
--------------------------------------------------------
Failed to mount database 'Mailbox Database'.
Mailbox Database 0610509261
Failed
Error:
Couldn't mount the database that you specified. Specified database: Mailbox Database; Error code: An Active Manager operation failed. Error: The database action failed. Error: Operation failed with message: MapiExceptionCallFailed: Unable to mount database. (hr=0x80004005, ec=-515)
. [Database: Mailbox Database, Server: server.domain.local].
An Active Manager operation failed. Error: The database action failed. Error: Operation failed with message: MapiExceptionCallFailed: Unable to mount database. (hr=0x80004005, ec=-515)
. [Database: Mailbox Database, Server: server.domain.local]
An Active Manager operation failed. Error: Operation failed with message: MapiExceptionCallFailed:
. [Server: server.domain.local]
MapiExceptionCallFailed: Unable to mount database. (hr=0x80004005, ec=-515)
Iterate through Hash of Hashes
Tuesday, 20 December 2011 09:10
Here's how you would iterate through multidimensional hashes in Perl:
Create a hash first:
#!/usr/bin/perl
use warnings;
use strict;
my %HoH = (
flintstones => {
husband => "fred",
wife => "wilma",
pal => "barney",
},
jetsons => {
husband => "george",
wife => "jane",
"his boy" => "elroy", # Key quotes needed.
},
simpsons => {
husband => "homer",
wife => "marge",
kid => "bart",
},
);
Connecting one system to multiple networks
Monday, 28 November 2011 15:17
Q. I have a Linux server that connects to the external network and internal. Both network cards have a gateway. How can I set it up, so that it can access both networks?
A. You would need to set up source routing. This can be done fairly easily, following those steps:
Open up /etc/iproute2/rt_tables, add those two at the bottom:
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