This site is a collection of scripts, hints, articles, and
programs. Reference my
notes page for ideas that I am currently working
on or sites that I am looking at for ideas. If you have an article or an idea for an article, please send it along. My goal
is to help the community any way that I can; but, learn as I go too.
MSSQL 2005 Tips
Simple and complete examples for performing common tasks
with Microsoft SQL Server 2005.
Performance Monitoring on Linux
Demonstrated examples using oprofile, IOzone, vmstat, smartmontools, and
the ps command are covered in this tutorial. This work-in-progress
covers profiling the kernel, generating stress tests, examining
memory swapping, querying the number of hours your drive has been
spinning plus getting the current, maximum and minimum temperatures.
Postfix 2nd Instance for Sender-based Routing: Multiple Gmail
and Comcast Accounts.
Configure your home system to support several Gmail accounts, and
additionally, Comcast and or other ISP accounts that require
individual authentication rules based on the sending address. This
tutorial walks you through configuring a second instance of Postfix,
on a second IP address (same NIC), with sender-based routing.
Linux Quota Tutorial
This tutorial walks you through implementing disk quotas for both users and
groups on Linux, using a virtual filesystem, which is a filesystem created
from a disk file. Since quotas work on a per-filesystem basis, this is a way
to implement quotas on a sub-section, or even multiple subsections of your
drive, without reformatting. This tutorial also covers quotactl, or quota's
C interface, by way of an example program that can store disk usage in a
SQLite database for monitoring data usage over time.
Gmail on Home Linux Box using Postfix and Fetchmail
If you have a Gmail account and would like to use it in conjunction with your
personal computers, this tutorial will walk you through configuring and installing the latest version of
Postfix with SASL authentication and TLS encryption necessary for connecting and relaying mail to
smtp.gmail.com and configuring fetchmail with STARTTLS to fetch messages from your Gmail account to your
local system. It will also discuss how to forward mail to other computers and how to
automatically backup copies of email messages.
Breaking Firewalls with OpenSSH and PuTTY
If the system administrator deliberately filters out all traffic except
port 22 (ssh), to a single server, it is very likely that you can still
gain access other computers behind the firewall. This article shows how
remote Linux and Windows users can gain access to firewalled samba,
mail, and http servers. In essence, it shows how openSSH and PuTTY can be
used as a VPN solution for your home or workplace.
Create your own custom Live Linux CD
These steps will show you how to create a functioning Linux system, with the
latest 2.6 kernel compiled from source, and how to integrate the BusyBox
utilities including the installation of DHCP. Plus, how to compile in
the OpenSSH package on this CD based system. On system boot-up a filesystem
will be created and the contents from the CD will be uncompressed and
completely loaded into RAM -- the CD could be removed at this point for
boot-up on a second computer. The remaining functioning system will have
full ssh capabilities. You can take over any PC assuming, of course,
you have configured the kernel with the appropriate drivers and the
PC can boot from a CD.
This article explores the power and simplicity of sqlite3, first by starting with common commands and triggers,
then the attach statement with the union operation is introduced in a way that allows multiple tables, in separate
databases, to be combined as one virtual table, without the overhead of copying or moving data. Next, the simple
sign function and the amazingly powerful trick of using this function in SQL select statements to solve
complex queries with a single pass through the data is demonstrated, after making a brief mathematical
case for how the sign function defines the absolute value and IF conditions.
Lemon Parser Tutorial
Lemon is a compact, thread safe, well-tested parser generator written by D. Richard Hipp. Using a parser
generator, along with a scanner like flex, can be advantageous because there is less code to write.
You just write the grammar for the parser. This article is an introduction to the Lemon Parser, complete
NTP, UTC, and Working with Time on Linux
This article defines what is meant by UTC, shows you how to use the date command to calculate the date for any timezone including with
or without dst. Plus you will see how to setup and confirm that NTP is working. There is also a program to calculate sunrise and sunset given
longitude and latitude in degrees.
There are over 200 Linux tips and tricks from using encryption, tar, cpio, setting up multiple IP addresses on
one NIC, tips for using man, putting jobs into the background, using shred, watch who is doing what on your
system, listing system settings, IPC status, how to make a file immutable so that even root cannot delete,
ssh key pair generation, keeping 12 months of backups in the system logs, low level tap commands (mt),
mount an ISO image as a filesystem, getting information on the hard drive, setting up cron jobs, look command,
getting a bigger word dictionary, find out if a command is aliased, ASCII codes, using elinks, screen commands,
FTP auto-login, Bash brace expansion, Bash string operators, for loops in Bash, diff and patch, script,
change library path (ldconfig), monitor file usage, --parents option in commands, advance usage of the
find command, cat tricks, guard against SYN flood attacks and ping, special shell variables, RPM usage,
finding IP and MAC address, DOS to UNIX conversion, PHP as command line scripting language, Gnuplot,
POVRAY and making animated GIFs, plus a lot more.
Virtual Filesystem: Building
a Linux Filesystem from an Ordinary File
You can take a disk file, format it as ext2, ext3, or reiser filesystem and then mount it, just like a physical drive. Yes, it then possible to read and write files to this newly mounted device. You can also copy the complete filesystem, since it is just a file, to another computer. If security is an issue, read on. This article will show you how to encrypt the filesystem, and mount it with ACL (Access Control Lists), which give you rights beyond the traditional read (r) write (w) and execute (x) for the 3 user groups file, owner and other.
How to Compile 2.6 kernel for RedHat 9 and 8.0 and get Fedora Updates
Upgrading Redhat 9 or 8.0 to the 2.6.x kernel. This is a step by step approach on how to compile the kernel
from source, then, get yum updates for all your other packages. There is also information and examples on
writing a 2.6 kernel module.
MySQL Tips and Tricks
Find out who is doing what in MySQL and how to kill the process, create binary log files,
connect, create and select with Perl and Java, remove duplicates in a table with the index command,
rollback and how to apply, merging several tables into one, updating foreign keys, monitor port 3306
with the tcpdump command, creating a C API, complex selects, and much more.
Comcast Email on Home Linux Box using Sendmail
Suppose you have accounts on your home Linux system that differ from the name of
your email accounts from your ISP. For instance, my email account (from comcast) is mchirico but the account I
have on my Linux box is chirico. What I wanted to do, is use the local chirico
account to get, create, send, email automatically as email@example.com. This
article will show you how to do that.
Working with Time on Linux
We still tell time by the sun. Yes, it is possible to go back in time. Want to know how
to check for intelligent alien life? Look for a precise time signal
HIGHLY RECOMMENDED BOOKS:
"UNIX Network Programming, The Sockets Networking API", Volume 1, Third Edition.
W. Richard Stevens, Bill Fenner, Andrew M. Rudoff.
"UNIX Network Programming, Interprocess Communications", Volume 2, Second Edition.
W. Richard Stevens.
"UNIX SYSTEMS Programming, Communication, Concurrency, and Threads", Kay A. Robbins,
"Programming with POSIX Threads", David R. Butenhof. Addison-Wesley
"The C++ Programming Language" Third Edition. Bjarne Stroustrup. Addison-Wesley.
"C Programming Language" (2nd Edition), Second Edition, Kernighan and Ritchie
"Advanced Linux Programming", Mark Mitchell, Jeffrey Oldham, and Alex Samuel, of
CodeSourcery LL. This book if free at the following resource:
"Accelerated C++, Practical Programming by Example", Andrew Koenig, Barbara E. Moo.
"C: A Reference Manual", Fifth Edition, Samuel P. Harbison, Guy L. Steele.
"C++ Standard Library: A Tutorial and Reference, The", Nicolai M. Josuttis. Addison Wesley.
"C++ Templates: The Complete Guide", David Vandevoorde, Nicolai M. Josuttis. Addison Wesley.
"Exceptional C++: 47 Engineering Puzzles, Programming Problems, and Solutions", Herb Sutter.
"More Exceptional C++", Herb Sutter.
"The Art of Computer Programming (TAOCP)", Vol 1,Vol 2, Vol 3. Donald E. Knuth. Addison-Wesley.
"Programming Perl, 3rd Edition", Tom Christiansen, Jon Orwant, Larry Wall. O'Reilly.
"Programming from the Ground Up", Jonathan Bartlett, Edited by Dominick Bruno, Jr.
"Expert C Programming", Peter van der Linden, Prentice Hall PTR.
HIGHLY RECOMMENDED: PHILOSOPHICAL
"Zen and the Art of Motorcycle Maintenance: An Inquiry into Values", Robert Pirsig.
"Lila: An Inquiry Into Morals", Robert Pirsig.
"Structure and Interpretation of Computer Programs", Harold Abelson, Gerald Jay Sussman,
Julie Sussman. This book is free:
Berkeleydb examples ,
these are simple examples on how C API to berkeleydb. Show below is some of the
the code in action. A database test.db is create and records are added. When you want
to extract the data, run the dump command.
$ ./add test.db "one two three"
$ ./add test.db "A bit more data"
$ ./dump test.db
1| one two three
2| A bit more data
Simple but common C programs , is
a colection of C programs like
open.c, a simple program for opening a file with a file descriptor;
getline.c a program to get a line at a time which can be compared to
readrealloc.c which demonstrates a realloc call. In this package, you
enum.cc and getopt.c. Plus, want an example of simple debugging with assert statement, then, take
a look at myassert.cc
Simple but Common C++ programs
is a collection of C++ programs, and includes
such programs as copy_if_trans.cc, which
demonstrates a copy_if and the transform statement to delete pointers in a container,
a custom predicate in a for_each statement for container elements,
permutation on a string,
which all show lists operations. Also included in this download are
programs such as
a collection of programs all using threads.
a collection of programs for scraping web pages.
Hex to Dec:
Need a quick way to convert Hex to
echo "ibase=16; BC" |bc
Works with addition and subtraction
echo "ibase=16;FF +A" | bc
Want to find out who's connected to your
computer without using netstat
...true, the listing is little-endian four-byte
hexadecimal..but see the awk
page or the README in the awk script download.
Need to encrypt a file?
openssl des3 -salt -in file.txt -out
Need to decrypt the
openssl des3 -d -salt -in file.des3 -out file.txt -k
Need to encrypt what you type? Enter the
following, then start typing but ^D to
openssl des3 -salt -out stuff.txt
Need to tar/zip and encrypt a whole directory
without a temp file?
tar -zcf - mydirectory|openssl des3 -salt
-out mydirectory.tar.gz.des3 -k mypassword
Need to decrypt the file
openssl des3 -d -salt -in mydirectory.tar.gz.des3 -k
Need to remove a file
shred -u file.txt
...for information see the README in the bash script