Tech Tips » UNIX

How To Setup Disk Quotas For MySQL Database

chandu — Mon, 28 Jan 2008 12:00:52 +0000

MySQL server has no support for preventing disk from getting filled up. You need to depend upon external configurations. Let us see how to use standard Linux disk quota to limit user database size.

Suppose you have a user foo on the system as well as on MySQL. Now how do you limit space for foo?

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How To Setup Disk Quotas For MySQL Database

Linux: Find out how many file descriptors are being used

chandu — Mon, 27 Aug 2007 09:40:08 +0000

While administrating a box, you may wanted to find out what a processes is doing and find out how many file descriptors (fd) are being used. You will surprised to find out that process does open all sort of files:
=> Actual log file
=> /dev files
=> UNIX Sockets
=> Network sockets
=> Library files /lib /lib64
=> Executables and [...]

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Linux: Find out how many file descriptors are being used

Understanding UNIX Multitasks operations and process command

chandu — Wed, 11 Apr 2007 12:07:59 +0000

Yet another good article from Martin Streicher , Editor-in-Chief, Linux Magazine that explains UNIX Multitasks (many concepts applies to Linux as well).

From the article:

On UNIX systems, each system and end-user task is contained within a process. The system creates new processes all the time and processes die when a task finishes or something unexpected happens. Here, learn how to control processes and use a number of commands to peer into your system.

UNIX has many moving parts. It has system services, devices, memory managers, and more. Luckily, most of these complex machinations are hidden from view or are made convenient to use through user interfaces, such as the shell and windowing tools. Better yet, if you want to dive in, specialized tools, such as top, ps, and kill, all are readily available.

Quick Tip: Use remote Linux GUI system, admin tools locally

chandu — Wed, 11 Apr 2007 11:47:39 +0000

Technology has changed dramatically in the last decade. OpenSSH is one the best project. It allows you to control remote Linux / UNIX server using command line or GUI tools.

Do you miss GUI configuration server management tools such as Debian network-admin or Redhat/Cent os system-config-* tools/utilities while administrating a Linux server? Do you want to run GUI admin tools on a remote Linux server and get display on local desktop or laptop X server system?

I have been using OpenSSH X11 forwarding and it works very well with DSL / ADSL/ cable connections.

[Read the full article here...]

Quick Tip: Use remote Linux GUI system, admin tools locally

Originally from nixCraft by nixcraft

Perl script to monitor disk space and send an email

chandu — Thu, 22 Feb 2007 15:16:24 +0000

How to write a perl script that can monitor my disk space under UNIX or Linux and send me an email alert?

There is a nice perl system routine called Perl df or Filesys::DiskSpace. This routine displays information on a file system such as its type, the amount of disk space occupied, the total disk space and the number of inodes etc.

Task: Install Filesys::DiskSpace

First you need to install this perl module using apt-get or from cpan (Comprehensive Perl Archive Network).
$ sudo apt-get install libfilesys-diskspace-perl

Perl script code to monitor disk space

Now write a perl script called df.pl:
$ vi df.pl
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Perl script to monitor disk space and send an email

Originally from nixCraft by nixcraft

Linux command editing examples using cat, ed, and sed

chandu — Wed, 17 Jan 2007 12:23:35 +0000

Linux and UNIX – Fast command line editing examples using cat, ed, and sed. Here is why you need to use command line editing tools�

#1: Text editor takes time for small editing
#2: Use command line editing
#3: Save time and impress your friends [ read as look like an elite UNIX hacker ]

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Linux command editing examples using cat, ed, and sed

Originally from nixCraft by nixcraft

Understanding UNIX process creation

chandu — Tue, 09 Jan 2007 04:22:41 +0000

With this tutorial you can explore the life cycle of a process running under the UNIX operating system.

Delve into UNIX process creation

[Read the full Article here...]

Understanding UNIX process creation

Originally from nixCraft by nixcraft

How to send anonymous email from shell prompt using mixmaster

chandu — Tue, 02 Jan 2007 06:27:14 +0000

You can send email with attachment via shell script or at shell prompt/command line using mutt or mail command. This will not hide your IP address.

To send anonymous email from shell prompt use Mixmaster, which is the type II remailer protocol and the most popular implementation of it.

[More in this Article..]

How to send anonymous email from shell prompt using mixmaster

Originally from nixCraft by nixcraft

How to protect buggy programs from security vulnerabilities under Linux and UNIX

chandu — Tue, 02 Jan 2007 06:18:53 +0000

A Buffer overflows is a serious security problem. It allows an attacker to inject executable code of their choice into an already-running application. This ability to run arbitrary code at certain memory addresses is dangerous as attacker being able to execute the instructions from anywhere in memory.

To protect bufferoverflow security vulnerabilities use diehard

With such problems in mind, Berger created a new program that prevents crashing and makes users safer, he says. Dubbed DieHard, there are versions for programs that run in Windows or Linux. DieHard is available free for non-commercial users at www.diehard-software.org.

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How to protect buggy programs from security vulnerabilities under Linux and UNIX

Originally from nixCraft by nixcraft

Linux bash shell command shortcuts and tips

chandu — Thu, 14 Dec 2006 04:32:47 +0000

Bourne-again shell (BASH) is default shell for most Linux distro as well as on Mac OS X Tiger, and it can be run on most Unix-like operating systems. It has also been ported to Microsoft Windows within the Cygwin POSIX emulation environment for Windows, and to MS-DOS by the DJGPP project.
This article covers bash shell [...]

Linux bash shell command shortcuts and tips

Originally from nixCraft by nixcraft

10 bad UNIX or Linux command line usage patterns to avoid

chandu — Thu, 14 Dec 2006 04:29:50 +0000

Michael Stutz is author of The Linux Cookbook, has published excellent set of 10 bad UNIX usage patterns. These are applies to Linux, OS X shell as well
You can adopt 10 good habits that improve your UNIX / Linux command line efficiency — and break away from bad usage patterns in the process. [...]

10 bad UNIX or Linux command line usage patterns to avoid

Originally from nixCraft by nixcraft

How to tunnel with SSH – Secure Windows to UNIX or Linux connectivity

chandu — Thu, 19 Oct 2006 06:43:53 +0000

Learn how to tunnel with ssh, to get Windows to UNIX connectivity in a secure world. With new security threats cropping up every day, network managers are understandably protective of their computing assets. Enhanced security measures, however, can inflict significant hardships on legitimate users and can lead to frustration, productivity losses, and dangerous attempts at circumvention of restrictions. Equipping yourself with proper tools for connectivity can make your tasks easier while still maintaining network security and integrity. One of the most valuable tools in the IT toolkit is Secure Shell (SSH).

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How to tunnel with SSH – Secure Windows to UNIX or Linux connectivity

Originally from nixCraft by nixcraft

TightVNC – Free Remote Control Tool

chandu — Thu, 19 Oct 2006 06:38:50 +0000

TightVNC is a free, cross-platform remote control software package derived from the popular VNC software. VNC stand for Vitual Network Computing which allow remotely view and fully-interact with one computer from any other computer or mobile device anywhere on the Internet. TightVNC includes better compression algorithms for improved performance over WAN links, as well as new features like automatic SSH tunneling between Unix/Linux hosts. It is designed to work over slow connections.

For more info about TightVNC�s features: http://www.tightvnc.com/intro.html

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TightVNC – Free Remote Control Tool

Originally from AdGlobe Tech Blog by noemail@noemail.org (carolyn)

How to extract an RPM package without installing it

chandu — Thu, 19 Oct 2006 06:32:20 +0000

Most of you may know to how extract a tarballs and/or a zip files. Someone recently PM me with a question:

How do I extract an RPM package without installing it on my Fedora Core Linux v5?

To be frank there is no direct RPM option available via rpm command to extract an RPM file. But there is a small nifty utility available called rpm2cpio. It Extract cpio archive from RPM Package Manager (RPM) package. With the following hack you will be able to extract an RPM file.

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How to extract an RPM package without installing it

Originally from nixCraft by nixcraft

UNIX File maintenance tools, tips and how tos collection

chandu — Thu, 05 Oct 2006 06:10:16 +0000

IBM developerworks has published excellent set of tips and howtos.

From the article:
Systems administrators can use a number of programs to maintain files in a UNIX system from the command line. In this tutorial, you�ll experiment with commands, such as cd, cp, and tar, to navigate a UNIX file system from the command line and work with files and directories. The cd command changes directories, cp duplicates files or directories, and tar quickly groups files into an archive. You�ll also learn how to deal with file permissions and perform simple input/output.

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UNIX File maintenance tools, tips and how tos collection

Originally from nixCraft by nixcraft

Prevent from using (reuse) same old passwords under Linux

chandu — Thu, 28 Sep 2006 13:05:11 +0000

PAM is a flexible mechanism for authenticating users.

There is a module called pam_unix. This module provides functionality for PAM modules such as authentication, account management etc.

Same module can be used to maintain a list of old passwords for every user. This is useful if you want to disallow use of old passwords.

[Read more in below Article...]

Originally from nixCraft by nixcraft

Linux or UNIX: How to find out or display the Ethernet Address (MAC)

chandu — Sat, 23 Sep 2006 07:33:01 +0000

Media Access Control (MAC) address is a unique identifier attached to most networking devices (such as router, Ethernet cards etc).

This address is some time required. For example, there is famous engineering expensive software. This software needs your unique MAC address to issue you license and necessary software installation keys. Some time MAC address used for filtering purpose (firewall or sniffers) or diagnosing network problems .

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Linux or UNIX: How to find out or display the Ethernet Address (MAC)

Originally from nixCraft by nixcraft

Howto: Linux Refresh all or an X screen Kde-Gnome desktop

chandu — Thu, 21 Sep 2006 17:49:27 +0000

Linux or UNIX desktop systems are quite stable. However, some time weird things happen like unreadable screen and confusing application causing massive screen messed up, which makes it difficult to read what is on the Linux desktop.

Generally, I have observed that most users prefer to hit CTRL+ALT+Back Space or just kills the X session. However, there is way to get rid of this problem.

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Howto: Linux Refresh all or an X screen Kde-Gnome desktop

Originally from nixCraft by nixcraft

Webmin Configuration in Ubuntu and Debian

chandu — Thu, 21 Sep 2006 17:39:12 +0000

Webmin is a web-based interface for system administration for Unix. Using any browser that supports tables and forms (and Java for the File Manager module), you can setup user accounts, Apache, DNS, file sharing and so on.

Webmin consists of a simple web server, and a number of CGI programs which directly update system files like /etc/inetd.conf and /etc/passwd. The web server and all CGI programs are written in Perl version 5, and use no non-standard Perl modules.

Read Full Article here

Webmin Configuration in Ubuntu and Debian

Originally from ArsGeek by david23

Howto switch from Linux to Windows – a users experience

chandu — Thu, 21 Sep 2006 17:35:17 +0000

I�ve read articles like �Switching for Windows to Linux in five easy steps� or �How changing your operating system can make fun with Linux� or �Why you should give Linux a chance� for five years now but there are always people who say Linux is difficult to learn and Windows has much easier install routines and so on. But what if the first OS you�ve ever used wasn�t MS Dos or Win95 but some kind of Unix-based free system like BSD or Linux?

This is a text about a guy who has always used Linux and learned working with it when he was a young man when he had to use it at work. Imagine Linux is the standard OS and Microsoft is a small company offering so called MS Windows XP. >>>>>

Howto switch from Linux to Windows – a users experience

Originally from Linux and Open Source Blog by E@zyVG

Download: Poderosa – Tabbed style SSH, Telnet client for Windows XP systems

chandu — Mon, 18 Sep 2006 14:34:29 +0000

Generally, I recommend using Putty to access Linux/UNIX from Windows XP.

Poderosa is terminal emulators for ssh and telnet protocol with following features:
=> Tabbed style GUI – You can open multiple ssh or telnet connection at the same time from a single window (just like firefox).
=> Moreover, you can split the window into panes and allocate each connection.
=> It also supports local cygwin shell and serial ports (great for testing and troubleshooting)
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Download: Poderosa – Tabbed style SSH, Telnet client for Windows XP systems

Originally from nixCraft by nixcraft

Windows Run commands: 112 ways to command Windows

chandu — Fri, 15 Sep 2006 05:07:20 +0000

112 Windows commands. I don’t know that this is something I would keep handy because I am too lazy to type all that in every time I wanted to run a program, which is why we have icons in this modern world. If you are a Linux/Unix geek, simply like carpal tunnel, or have a penchant for painful memory overruns (in your head) I can see using this. I don’t know who put this up, but it looks like a personal cheat sheet that you could print out and reference on occasion if you need to do something special you can’t find easily elsewhere on your PC. I like lists of commands, codes, and other jazz.
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Windows Run commands: 112 ways to command Windows

Originally from Download Squad by Ryan Carter

How to Mount USB Disk Drive in UNIX or Linux

chandu — Sun, 10 Sep 2006 03:24:41 +0000

Most distros (distributions) of Linux include Mandrake 10.1, SuSE 9.x and Fedora Core 3 can now support plug-and-plug detection, discovery and driver installation for portable USB drive or USB disk (and any type of USB-based data storage devices devices such as hard drives, pen drives, USB keys, flash disk, thumb drive, memory key, USB zip [...]

How to Mount USB Disk Drive in UNIX or Linux

Originally from My Digital Life by Administrator

Obtain Whois Information from the Windows Command Prompt

chandu — Fri, 08 Sep 2006 04:09:13 +0000

Today’s tip is on obtaining domain registration data from the Windows Command Prompt. The whois command is a standard fixture in the Linux/Unix world, but Windows users typically need to resort to web based applications to query Whois information. We’ll be taking a look at a small utility called WhoisCL, which will allow you to query whois servers from the Command Prompt as well as from within batch files.

WhoisCL, an application developed by Nir Sofer, can be downloaded from here. Once you have downloaded the application, unzip the WhoisCL.exe file and place it in your path (i.e. C:\Windows). After you have extracted the file, you may want to rename it to whois.exe to make the command easier to remember, especially if you find yourself working on Linux machines frequently.

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Obtain Whois Information from the Windows Command Prompt

Originally from Jameser's Tech Tips by Jameser

How to share a folder with Read/Write access using Samba on Linux

chandu — Wed, 30 Aug 2006 03:28:41 +0000

Here�s my setup. I�ve got a large network that�s accessible by hordes of people. On this network I have an Ubuntu box acting as a file server. I want a limited number of folks to be able to put files on it, take files off of it and access it from a number of different operating systems (OSX, Windows and Linux). How to do that? Well, the unix folks can use ssh and scp to connect and move files around (as can the more advanced windows folks)but for graphical sharing or mapping a network drive via Windows, we need Samba to get involved.

[Read more in below article ...]

How to share a folder with Read/Write access using Samba on Linux

Originally from ArsGeek by arsgeek

Ubuntu basics – how to add extra repositories to get neat stuff

chandu — Tue, 29 Aug 2006 15:48:57 +0000

Want to add extra repositories in Ubuntu? Here�s how to do it.

Ubuntu basics – how to add extra repositories to get neat stuff

Originally from ArsGeek by arsgeek

How to delete write protected file

chandu — Sat, 26 Aug 2006 12:25:38 +0000

Reader Ashish asks �How to delete write protected file under Linux��

Under Linux (and other Unixsh oses) following criteria should matched before deleting a file:

Criteria # 1

To delete or remove a file you need to be owner of a file. Use ls -l command to verify your ownership:
$ ls -l filename

If you have sufficient rights, you can remove a file. Otherwise, become a superuser to remove a file.

Criteria # 2

In addition, you must have a write access to on a directory that allows you to remove or add new files. Again us ls -l or ls -ld command to get write ownership of directory.
$ ls -ld dirname

If you have sufficient rights, you can remove a file. Otherwise, become a superuser to remove a file. Use chown / chmod commands to setup permission OR run rm command as root user:
# su - # rm -f file.txt

[More on NixCraft below...]

How to delete write protected file

Originally from nixCraft by nixcraft

Linux and UNIX Backing up key information or files

chandu — Wed, 16 Aug 2006 06:08:15 +0000

Martin Brown shows us how to backup key files using tar and perl / shell scripts. It is a good article for all new sys admins (this goes well with my own shell scripts collection).

Most UNIX administrators have processes in place to back up the data and information on their UNIX machines, but what about the configuration files and other elements that provide the configuration data your machines need to operate? This article provides detailed information on techniques for achieving an effective and efficient backup system for these key files

Take a closer look at OpenBSD

chandu — Sun, 13 Aug 2006 08:36:33 +0000

OpenBSD is quite possibly the most secure operating system on the planet. Every step of the development process focuses on building a secure, open, and free platform. UNIX� and Linux� administrators take note: Without realizing it, you probably use tools ported from OpenBSD every day. Maybe it’s time to give the whole operating system a closer look.

When security is of the utmost importance, it’s only logical to look to the same operating system that spawned today’s standard in secure remote access, OpenSSH (Open Secure Shell). OpenSSH is just one part of OpenBSD, a distribution that has focused on security from the ground up, accomplishing a goal of creating a UNIX�-like operating system that is secure by default. This stand is in contrast to most operating systems today, which require significant time and energy to harden the environment before going live. In fact, OpenBSD is so secure that it was once banned for use in a DEF CON competition, where crackers go after each other’s systems.

Complete Review by IBM developerWorks

Take a closer look at OpenBSD

Originally from Linux and Open Source Blog by E@zyVG