LINUXLinux is a generic term referring to the family of Unix-like computer operating systems that use the Linux kernel.
Their development is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License.
Linux can be installed on a wide variety of computer hardware , ranging from embedded devices such as mobile phones, smartphones and wristwatches to mainframes and supercomputers.
Linux is predominantly known for its use in servers; in 2007 Linux's overall share of the server market was estimated at 12.7%, while a 2008 estimate suggested that 60% of all web servers ran Linux.
Most desktop computers run either Mac OS X or Microsoft Windows, with Linux having only 12% of the desktop market.
However, desktop use of Linux has become increasingly popular in recent years, partly owing to the popular Mandriva Linux, Fedora, Debian or Ubuntu distributions and the emergence of netbooks and smartbooks.
Linux installation To install Red Hat, you will need to download the ISO images (CD Images) of the installation CD-ROMs from http://fedora.redhat.com Download the i386 images for 32 Intel Processors, PPC images for for Apple Macintosh and x86_64 for for 64 bit AMD Processors Burn the iso CD images on CDs and use these CDs as Installation CDs (typically 4)
Linux file structureIn the Linux file structure files are grouped according to purpose. Ex: commands, data files, documentation. Parts of a Unix directory tree are listed below. All directories are grouped under the root entry "/". That part of the directory tree is left out of the below diagram. See the FSSTND standard (Filesystem standard) * root - The home directory for the root user * home - Contains the user's home directories along with directories for services o ftp o HTTP o samba o george
bin - Commands needed during bootup that might be needed by normal users
sbin - Like bin but commands are not intended for normal users. Commands run by LINUX. proc - This filesystem is not on a disk. It is a virtual filesystem that exists in the kernels imagination which is memory. A directory with info about process number 1. Each process has a directory below proc. usr - Contains all commands, libraries, man pages, games and static files for normal operation. bin - Almost all user commands. some commands are in /bin or /usr/local/bin. sbin - System admin commands not needed on the root filesystem. e.g., most server programs. include - Header files for the C programming language. Should be below /user/lib for consistency. lib - Unchanging data files for programs and subsystems
local - The place for locally installed software and other files. man - Manual pages info - Info documents doc - Documentation tmp X11R6 - The X windows system files. There is a directory similar to usr below this directory. X386 - Like X11R6 but for X11 release 5 boot - Files used by the bootstrap loader, LILO. Kernel images are often kept here. lib - Shared libraries needed by the programs on the root filesystem modules - Loadable kernel modules, especially those needed to boot the system after disasters. dev - Device files etc - Configuration files specific to the machine.
skel - When a home directory is created it is initialized with files from this directory
sysconfig - Files that configure the linux system for devices.
var - Contains files that change for mail, news, printers log files, man pages, temp files
lib - Files that change while the system is running normally
local - Variable data for programs installed in /usr/local.
lock - Lock files. Used by a program to indicate it is using a particular device or file
log - Log files from programs such as login and syslog which logs all logins and logouts.
run - Files that contain information about the system that is valid until the system is next booted
spool - Directories for mail, printer spools, news and other spooled work.
tmp - Temporary files that are large or need to exist for longer than they should in /tmp.
catman - A cache for man pages that are formatted on demand mnt - Mount points for temporary mounts by the system administrator. Tmp - Temporary files. Programs running after bootup should use /var/tmp.
Basic commands in linux1.Cat: Sends file contents to standard output. This is a way to list the contents of short files to the screen.
Example: cat .bashrc
Description: It works well with piping.Sends the contents of the ".bashrc" file to the screen.
2.Cd: Change directory Example: cd /home Description: Change the current working directory to /home. The '/' indicates relative to root, and no matter what directory you are in when you execute this command, the directory will be changed to "/home".
Example: cd httpdDescription: Change the current working directory to httpd, relative to the current location which is "/home". The full path of the new working directory is "/home/httpd".
3. Cp : Copy files Example: cp myfile yourfile Description: Copy the files "myfile" to the file "yourfile" in the current working directory. This command will create the file "yourfile" if it doesn't exist. It will normally overwrite it without warning if it exists.
Example: cp -dpr srcdir destdir Description: Copy all files from the directory "srcdir" to the directory "destdir" preserving links (-p option), file attributes (-p option), and copy recursively (-r option). With these options, a directory and all it contents can be copied to another directory.
4.Dd : Disk duplicate Example: dd if=/dev/hdb1 of=/backup/ Description: The man page says this command is to "Convert and copy a file", but although used by more advanced users, it can be a very handy command. The "if" means input file, "of" means output file.
5.Df: Show the amount of disk space used on each mounted filesystem.
6. ls:List files Example: lsDescription: List files in the current working directory except those starting with . and only show the file name. Example : ls -alDescription: List all files in the current working directory in long listing format showing permissions, ownership, size, and time and date stamp
7.mv:Move or rename files Example: mv -i myfile yourfileDescription: Move the file from "myfile" to "yourfile". This effectively changes the name of "myfile" to "yourfile". Example: mv -i /data/myfile .Description: Move the file from "myfile" from the directory "/data" to the current working directory.
8. pwd:Show the name of the current working directory Example: more /etc/profileDescription: Lists the contents of the "/etc/profile" file to the screen one page at a time.
Apache The Apache is web server software notable for playing a key role in the initial growth of the World Wide Web.
In 2009 it became the first web server software to surpass the 100 million web site milestone.
Apache was the first viable alternative to the Netscape Communications Corporation web server (currently known as Sun Java System Web Server), and has since evolved to rival other Unix-based web servers in terms of functionality and performance. The majority of web servers using Apache run a Unix-like operating system.
Configuration ServerRoot: The top of the directory tree under which the server's configuration, error, and log files are kept.
Example: ServerRoot "/opt/lampp"
Listen: Allows you to bind Apache to specific IP addresses and/or ports, instead of the default. See also the directive. Example: Listen 220.127.116.11:80 Listen 80
Your address, where problems with the server should be e-mailed. This address appears on some server-generated pages, such as error documents. e.g. firstname.lastname@example.org
Example: ServerAdmin email@example.com
The directory out of which you will serve your documents. By default, all requests are taken from this directory, but symbolic links and aliases may be used to point to other locations.
Example: DocumentRoot "/opt/lampp/htdocs"
User/Group: The name (or #number) of the user/group to run httpd as. It is usually good practice to create a dedicated user and group for running httpd, as with most system services.
DirectoryIndex: sets the file that Apache will serve if a directory is requested.
#DirectoryIndex index.html # XAMPP DirectoryIndex index.html index.html.var index.php index.php3 index.php4
ErrorLog: The location of the error log file. If you do not specify an ErrorLog directive within a container,