UNIX / Linux: HowTo Use unison File Synchronizer
December 15th, 2010 by upa_kid
I know how to use www.cyberciti.biz/tips/linux-use-rsync-transfer-mirror-files-directories.html”>rsync for Unix systems which synchronizes files and directories from one location to another while minimizing data transfer. However, I would like to synchronizing files between two directories, either on one computer, or between a computer and another server. How do I maintain the same version...
Encrypt data in Linux/Unix
November 16th, 2010 by upa_kid
Do you have files on your computer that you wouldn’t want your spouse to read, or perhaps your main competitor. Chances are if you use your computer for work or general usage the answer is yes. Also what happens if you want to send a file to someone, or let them download it from you, but you only have access to the coded file.
OpenSSL :
The OpenSSL Project is a collaborative effort to...How to: Troubleshoot UNIX / Linux BIND DNS server problems
November 15th, 2010 by upa_kid
BIND is the Berkeley Internet Name Domain, DNS server. It is wildly used on UNIX and Linux like oses. You can use following tools to troubleshoot bind related problems under UNIX or Linux oses.
Task: Port 53 open and listing requests
By default BIND listen DNS queries on port 53. So make sure port 53 is open and listing user requests. by running any one of the following tests. See if you can telnet...Linux or UNIX Recover deleted files – undelete files
November 15th, 2010 by upa_kid
If you rum rm command accidentally and deleted important a file, recovery becomes critical under Linux and/or UNIX oses.
Since Linux is multiuser and multitasking operating system other users/process can overwrite deleted file disk space. So you need to take down system to single user mode.
First use wall (only the super-user can write on the terminals of users) command write a message to all users,...Bash Shell Find out Linux / FreeBSD / UNIX system load average
November 15th, 2010 by upa_kid
Yes, I know we can use uptime command to find out system load average. If you try to use uptime command in script, you know how difficult it is to get correct load average. As the time since the last, reboot moves from minutes, to hours, and an even day after system rebooted. Just time uptime
$ uptime
Output:
1:09:01 up 29 min, 1 user, load average: 0.00, 0.00, 0.00
$ uptime
Output:
2:13AM up 34 days,...Linux / UNIX: Scanning network for open ports with nmap command
November 15th, 2010 by upa_kid
You can use nmap tool for this job. It is flexible in specifying targets. User can scan entire network or selected host or single server. Nmap is also useful to test your firewall rules. namp is metwork exploration tool and security / port scanner. According to nmap man page:
It is an open source tool for network exploration and security auditing. It was designed to rapidly scan large networks, although...Linux / UNIX: Finding and locating files with find command part # 2
November 15th, 2010 by upa_kid
In the first part we talked about find command basic usage.
Now let us see how to use find command
(a) To gain lots of useful information about users and their files
(b) Monitor and enhance the security of system using find command
Finding all set user id files
setuid (“suid”) and setgid are access right flags that can be assigned to files and directories on a Unix based operating system....Understanding UNIX / Linux file system
November 15th, 2010 by upa_kid
A conceptual understanding of file system, especially data structure and related terms will help you become a successful system administrator. I have seen many new Linux system administrator w/o any clue about file system. The conceptual knowledge can be applied to restore file system in an emergency situation.
What is a File?
File are collection of data items stored on disk. Or it’s device...Understanding UNIX / Linux filesystem Superblock
November 15th, 2010 by upa_kid
This is second part of “Understanding UNIX/Linux file system”, part I is here. Let us take an example of 20 GB hard disk. The entire disk space subdivided into multiple file system blocks. And blocks used for what?
Unix / Linux filesystem blocks
The blocks used for two different purpose:
1. Most blocks stores user data aka files (user data).
2. Some blocks in every file system store...Unix beats Windows – says Microsoft!
November 15th, 2010 by upa_kid
Yet another claim from Microsoft. It includes some performance comparisons that show Singularity beating everything else on a 1.8Ghz AMD Athlon-based machine. The report is here and more comments here
We say nothing to see here let us move on
Jem Matzan wrote review of FreeBSD 6.0. The FreeBSD operating system is finally through it’s buggy 5.x series and into the more reliable 6.x series....Understanding UNIX / Linux filesystem Inodes
November 15th, 2010 by upa_kid
The inode (index node) is a fundamental concept in the Linux and UNIX filesystem. Each object in the filesystem is represented by an inode. But what are the objects? Let us try to understand it in simple words. Each and every file under Linux (and UNIX) has following attributes:
=> File type (executable, block special etc)
=> Permissions (read, write etc)
=> Owner
=> Group
=> File Size
=>...Understanding UNIX / Linux filesystem directories
November 15th, 2010 by upa_kid
You use DNS (domain name system) to translate between domain names and IP addresses.
Similarly files are referred by file name, not by inode number. So what is the purpose of a directory? You can groups the files according to your usage. For example all configuration files are stored under /etc directory. So the purpose of a directory is to make a connection between file names and their associated...