Allicient

RAID levels In Operating System

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RAID (redundant array of independent disks; originally redundant array of inexpensive disks) is a way of storing the same data in different places (thus, redundantly) on multiple hard disks. By placing data on multiple disks, I/O (input/output) operations can overlap in a balanced way, improving performance. Since multiple disks increases the mean time between failures (MTBF), storing data redundantly also increases fault tolerance. TABLE OF CONTENTS: RAID level 0: Striping RAID level 1: Mirroring and performance improvements RAID level 3: Byte-level parity RAID level 4: Block-level parity RAID level 5: Rotating parity RAID level 6: Tolerates failure of two disk drives RAID 0 Technically speaking RAID 0 is not a RAID level, but it is customarily viewed as RAID. Let’s say that you have three disk drives. Instead of writing everything on the first disk drive, you split the data up. So the first chunk of that file would be placed on disk one, the next chunk would be placed on disk two and the final chunk would be placed on disk three. You would then repeatedly rotate around that until the file is actually included on the correct array. You should think of RAID 0 as striping. Essentially, you have broken the file data down into pieces and placed them in the first, second and third arrays until they land in the correct array. Instead of reading the data from one disk drive, you now read the data parallel from all disk drives and then you combine the data on the other end. Essentially, you end up getting the performance of three disk drives and therefore the access of that file is vastly improved. This is classic striping. So the performance factor in RAID 0 improves because you have three disk drives pumping data back at you. There is also no impact on the availability of the data. If one of those three disk drives dies, your whole file is ruined because you do not have any coherent, consistent data, you have a chunk missing. RAID 1 RAID 1, also known as mirroring, is essentially where you have two disk drives and whatever you put on disk one, you simultaneously put on disk two. The idea is that if one of those two disks dies, then you have the other disk that is still working and therefore you achieve data availability improvements. You can also achieve performance improvements with RAID 1. When everything is functioning correctly — both of the disk drives are spinning, behaving properly and you’re reading data from both disk drives — you’re read performance will improve double for all practical purposes. There is a performance improvement in the situation of read, but not in terms if write. You also achieve extra availability of your data, because if one disk drive dies, you can access your information from the other disk drive. RAID 3 RAID 3 is the process of gaining up a certain number of disk drives, with the minimum number of drives being three. For this particular example, we’ll use five disk drives. Four of those disk drives would be data disks drives and the fifth would actually be a parity disk drive. The idea is that you have striped the data on the first four disk drives and then you calculate a parity from those drives to be placed on the fifth disk drive. In this type of situation, if any of those single disk drives fail, you can actually re-create that information by using the other four disk drives that are still working. So RAID 3 is very common in large, sequential workloads, such as video files. You want to be able to read a video file very quickly and you want to keep going from one end to the other. Very often, video files prefer to use RAID 3; you lock the first four drives in the example and just start extracting information from those drives in a rapid fashion. Performance and availability both improve greatly because any one of those five disk drives can die, but your data will still be safe. RAID 4 RAID 4 is very similar to RAID 3 in that a parity disk drive is always one of the five associated disk drives. But the difference is instead of doing the parity at the byte level, in RAID 4, the parity is done at the block level. The difference between RAID 3 and RAID 4 is very minor, and is only really applicable when you start looking at the finer art of RAID systems. Beyond performing parity at the byte level, the amount of data that is considered a chunk also differentiates RAID 4 from RAID 3. RAID 5 RAID 5 is very similar to RAID 3 and is probably the most popular level of the technology. In RAID five, the last disk drive is not the only drive that contains parity data in the array. In RAID 5, you rotate the parity in the five disk drives. So the first array may contain four drives of data and then one drive of parity, then the next array would contain three disks of data and then two disks of parity. In essence, parity is moved around in a round robin-type fashion. All five disk drives have a combination of data and parity. Again, if a single disk drive in that pairing dies, you can re-create that information from the remaining four disk drives. So you can tolerate a single disk drive failure, which improves the availability of data. This also improves performance because you are striping the data on the other four disk drives. RAID 6 RAID 6 is similar to RAID 5 in terms of striping and parity, with the major difference being that RAID 6 can tolerate two disk drives failing. In RAID 6, up to two disk drives can die and you can still have an efficient level of data availability. - See more at: http://localhost:81/test/raid-levels-in-operating-system/#sthash.oN65zYyb.dpuf</div>

RAID levels In Operating System

RAID (redundant array of independent disks; originally redundant array of inexpensive disks) is a way of storing the same data in differen...

Distributed Operating System & Parallel operating systems

Theallicient 0 Operating System 15:20

<div dir="ltr" style="text-align: left;" trbidi="on">
Distributed Operating System:- It is a model where distributed applications are running on multiple computers linked by communications. A distributed operating system is an extension of the network operating system that supports higher levels of communication and integration of the machines on the network. This system looks to its users like an ordinary centralized operating system but runs on multiple, independent central processing units (CPUs).                              <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3abUPLSCZtvpPedxQpGI6OmaGX1o2jnjrmDihPV7rk5_WEmlG09OVDt8DcgVolBlaEdc9J6qUNKb4Af61BLK2qhHOlTJYldQdqc9koPt-R0E4FEoCKJxYDlCtjzfTd-qoj8yU7M49Fy-L/s1600/Node_Organization-Distributed_Model@allicient.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="316" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3abUPLSCZtvpPedxQpGI6OmaGX1o2jnjrmDihPV7rk5_WEmlG09OVDt8DcgVolBlaEdc9J6qUNKb4Af61BLK2qhHOlTJYldQdqc9koPt-R0E4FEoCKJxYDlCtjzfTd-qoj8yU7M49Fy-L/s1600/Node_Organization-Distributed_Model@allicient.png" width="400" /></a> These systems are referred as loosely coupled systems where each processor has its own local memory and processors communicate with one another through various communication lines, such as high speed buses or telephone lines. By loosely coupled systems, we mean that such computers possess no hardware connections at the CPU – memory bus level, but are connected by external interfaces that run under the control of software. Parallel operating systems :- Parallel operating systems are used to interface multiple networked computers to complete tasks in parallel. The architecture of the software is often a UNIX-based platform, which allows it to coordinate distributed loads between multiple computers in a network. Parallel operating systems are able to use software to manage all of the different resources of the computers running in parallel, such as memory, caches, storage space, and processing power. Parallel operating systems also allow a user to directly interface with all of the computers in the network. A parallel operating system works by dividing sets of calculations into smaller parts and distributing them between the machines on a network. To facilitate communication between the processor cores and memory arrays, routing software has to either share its memory by assigning the same address space to all of the networked computers, or distribute its memory by assigning a different address space to each processing core. Sharing memory allows the operating system to run very quickly, but it is usually not as powerful. When using distributed shared memory, processors have access to both their own local memory and the memory of other processors; this distribution may slow the operating system, but it is often more flexible and efficient.</div>

Distributed Operating System & Parallel operating systems

Distributed Operating System:- It is a model where distributed applications are running on multiple computers linked by communications. A d...

Check Who is Accessing your Wireless Connection

Unknown 0 Softwares and Utilities 16:04

<div dir="ltr" style="text-align: left;" trbidi="on"><div class="separator" style="clear: both; text-align: center;"></div>Wireless Network Watcher is a small utility that scans your wireless network and displays the list of all computers and devices that are currently connected to your network. 
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgl-bO7GvEggS370oZfBoVsn4aVqycV5OaKQVgdXqvL8dXAuUtIW1vjFNsyiqvXTmd_4LlvI5vbs0hWCAwEK3cKsbVoZYu3hlumBvfT5pWkjUNIHhmDTIYYgBPIJoAb_bOj7bo1g2jof21T/s1600/wifi_logo@allicient.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgl-bO7GvEggS370oZfBoVsn4aVqycV5OaKQVgdXqvL8dXAuUtIW1vjFNsyiqvXTmd_4LlvI5vbs0hWCAwEK3cKsbVoZYu3hlumBvfT5pWkjUNIHhmDTIYYgBPIJoAb_bOj7bo1g2jof21T/s1600/wifi_logo@allicient.png" /></a></div> 
 
For every computer or device that is connected to your network, the following information is displayed: IP address, MAC address, the company that manufactured the network card, and optionally the computer name. This would help you quickly note down the culprit who has gained access to your wireless network unauthorized 
 
You can also export the connected devices list into html/xml/csv/text file, or copy the list to the clipboard and then paste into Excel or other spreadsheet application. 
 
<div class="separator" style="clear: both; text-align: center;"><a href="https://www.dropbox.com/s/oh7eenkkxdx1xek/WNetWatcher.zip?dl=0" target="_blank"><img alt="download_now" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiyyFFA1UjU1z5XpJ1LHoS8r4UucFlOJW1XF03KHQ2KYD6ZWc64YbpM9gi2Vog4x1l_a0lEKS340p57LteEuliwAFg7yLmtydNwYqCWn9O_JLMs2G0dQ_lfricvSjCb7jZBuTVgG__vCKH4/s1600/download_icon@allicient.png" /></a></div> 
</div>

Check Who is Accessing your Wireless Connection

Wireless Network Watcher is a small utility that scans your wireless network and displays the list of all computers and devices that are cur...

Create Nameless Files & Folders in windows Xp

Unknown 0 Tips and Tricks 15:55

<div dir="ltr" style="text-align: left;" trbidi="on"><div class="separator" style="clear: both; text-align: center;"> 
</div>This Trick will allow you to create files and folders without any name only in windowsXp. 
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidEN0SYtDeKNVSCsDX2H8VTrC5FDPEehGkELLKFZkXho7PVIJXenbKHKAVNYhnZnmkTWvJuE2Fm0r9GAgjgZ8wLEeAFVtjCJKrqIFN9SH4lyaRh7nslRQnppb8ikqplVX6NR0mT453pHOo/s1600/win_xp_tricks@allicient.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidEN0SYtDeKNVSCsDX2H8VTrC5FDPEehGkELLKFZkXho7PVIJXenbKHKAVNYhnZnmkTWvJuE2Fm0r9GAgjgZ8wLEeAFVtjCJKrqIFN9SH4lyaRh7nslRQnppb8ikqplVX6NR0mT453pHOo/s1600/win_xp_tricks@allicient.png" width="200" /></a></div> 
 
Just follow the following Steps: 
 
1.Select any file or folder. 
 
2.Right click on it, press rename or simply press F2. 
 
3.Press and hold the alt key. While holding the Alt key, type numbers 0160 from the numpad. 
 
Note: Type the numbers 0160 from the numpad, that is, the numbers present on the right side of the keyboard. Don’t type the numbers which are present on top of the character keys. 
 
4.Press Enter and the nameless file or folder will be created. 
 
Reason: The file or folder that seems nameless is actually named with a single space. 
 
But what if you want to create another nameless file or folder in the same directory ? 
 
For this you will have to rename the file with 2 spaces. Just follow these steps below: 
 
1.Select file, press F2. 
 
2.Hold alt key and type 0160 from the numpad. 
 
3.Release the alt key. Now without doing anything else, again hold alt key and press 0160. 
 
4.Press enter and you will have second nameless file in the same directory. 
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjijjC0OwkBmXNrTuy2AHa_dYFiLkoKsTWGAUqdySLOLwDPpkbIoXkSWD2fpdUwig1-s-jFl9XQxf9G6pL_MJuqdBM8AirjxTl4oBgHjrxWf0DGN-4t7wqoEfTUzprqIvnQ1LvSO8pUnjrp/s1600/without_name@allicient.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjijjC0OwkBmXNrTuy2AHa_dYFiLkoKsTWGAUqdySLOLwDPpkbIoXkSWD2fpdUwig1-s-jFl9XQxf9G6pL_MJuqdBM8AirjxTl4oBgHjrxWf0DGN-4t7wqoEfTUzprqIvnQ1LvSO8pUnjrp/s1600/without_name@allicient.jpg" /></a></div>5.Repeat step 3 to create as many nameless files or folders in the same directory. 
</div>

Create Nameless Files & Folders in windows Xp

This Trick will allow you to create files and folders without any name only in windowsXp. Just follow the following Steps: 1.Select an...

Linux Commands for System Administrators

Unknown 0 Tips and Tricks 15:50

<div dir="ltr" style="text-align: left;" trbidi="on">1. Uptime Command 
In Linux uptime command shows since how long your system is running and the number of users are currently logged in and also displays load average for 1,5 and 15 minutes intervals. 
 
# uptime 
 
08:16:26 up 22 min,  1 user,  load average: 0.00, 0.03, 0.22 
 
Check Uptime Version 
 
Uptime command don’t have other options other than uptime and version. It gives information only in hours:mins if it less than 1 day. 
 
[tecmint@tecmint ~]$ uptime -V 
procps version 3.2.8 
 
2. W Command 
 
It will displays users currently logged in and their process along-with shows load averages. also shows the login name, tty name, remote host, login time, idle time, JCPU, PCPU, command and processes. 
 
# w 
 
08:27:44 up 34 min,  1 user,  load average: 0.00, 0.00, 0.08 
USER     TTY   FROM      LOGIN@   IDLE   JCPU   PCPU WHAT 
tecmint  pts/0    192.168.50.1     07:59    0.00s  0.29s  0.09s w 
 
Available options 
 
    -h : displays no header entries. 
    -s : without JCPU and PCPU. 
    -f : Removes from field. 
    -V : (upper letter) – Shows versions. 
 
3. Users Command 
 
Users command displays currently logged in users. This command don’t have other parameters other than help and version. 
 
# users 
 
tecmint 
 
4. Who Command 
 
who command simply return user name, date, time and host information. who command is similar to w command. Unlike w command who doesn’t print what users are doing. Lets illustrate and see the different between who and w commands. 
 
# who 
 
tecmint  pts/0        2012-09-18 07:59 (192.168.50.1) 
 
# w 
 
08:43:58 up 50 min,  1 user,  load average: 0.64, 0.18, 0.06 
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT 
tecmint  pts/0    192.168.50.1     07:59    0.00s  0.43s  0.10s w 
 
Who command Options 
 
    -b : Displays last system reboot date and time. 
    -r : Shows current runlet. 
    -a, –all : Displays all information in cumulatively. 
 
5. Whoami Command 
 
whoami command print the name of current user. You can also use “who am i” command to display the current user. If you are logged in as a root using sudo command “whoami” command return root as current user. Use “who am i” command if you want to know the exact user logged in. 
 
# whoami 
 
tecmint 
 
6. ls Command 
 
ls command display list of files in human readable format. 
 
# ls -l 
 
total 114 
dr-xr-xr-x.   2 root root  4096 Sep 18 08:46 bin 
dr-xr-xr-x.   5 root root  1024 Sep  8 15:49 boot 
 
Sort file as per last modified time. 
 
# ls -ltr 
 
total 40 
-rw-r--r--. 1 root root  6546 Sep 17 18:42 install.log.syslog 
-rw-r--r--. 1 root root 22435 Sep 17 18:45 install.log 
-rw-------. 1 root root  1003 Sep 17 18:45 anaconda-ks.cfg 
 
7. Crontab Command 
 
List schedule jobs for current user with crontab command and -l option. 
 
# crontab -l 
 
00 10 * * * /bin/ls >/ls.txt 
 
Edit your crontab with -e option. In the below example will open schedule jobs in VI editor. Make a necessary changes and quit pressing :wq keys which saves the setting automatically. 
 
# crontab -e 
 
8. Less Command 
 
less command allows quickly view file. You can page up and down. Press ‘q‘ to quit from less window. 
 
# less install.log 
 
Installing setup-2.8.14-10.el6.noarch 
warning: setup-2.8.14-10.el6.noarch: Header V3 RSA/SHA256 Signature, key ID c105b9de: NOKEY 
Installing filesystem-2.4.30-2.1.el6.i686 
Installing ca-certificates-2010.63-3.el6.noarch 
Installing xml-common-0.6.3-32.el6.noarch 
Installing tzdata-2010l-1.el6.noarch 
Installing iso-codes-3.16-2.el6.noarch 
 
9. More Command 
 
more command allows quickly view file and shows details in percentage. You can page up and down. Press ‘q‘ to quit out from more window. 
 
# more install.log 
 
Installing setup-2.8.14-10.el6.noarch 
warning: setup-2.8.14-10.el6.noarch: Header V3 RSA/SHA256 Signature, key ID c105b9de: NOKEY 
Installing filesystem-2.4.30-2.1.el6.i686 
Installing ca-certificates-2010.63-3.el6.noarch 
Installing xml-common-0.6.3-32.el6.noarch 
Installing tzdata-2010l-1.el6.noarch 
Installing iso-codes-3.16-2.el6.noarch 
--More--(10%) 
 
10. CP Command 
 
Copy file from source to destination preserving same mode. 
 
# cp -p fileA fileB 
 
You will be prompted before overwrite to file. 
 
# cp -i fileA fileB 
 
11. MV Command 
 
Rename fileA to fileB. -i options prompt before overwrite. Ask for confirmation if exist already. 
 
# mv -i fileA fileB 
 
12. Cat Command 
 
cat command used to view multiple file at the same time. 
 
# cat fileA fileB 
 
You combine more and less command with cat command to view file contain if that doesn’t fit in single screen / page. 
 
# cat install.log | less 
 
# cat install.log | more 
 
13. Cd command (change directory) 
 
with cd command (change directory) it will goes to fileA directory. 
 
# cd /fileA 
 
14. pwd command (print working directory) 
 
pwd command return with present working directory. 
 
# pwd 
 
/root 
 
15. Sort command 
 
Sorting lines of text files in ascending order. with -r options will sort in descending order. 
 
#sort fileA.txt 
 
#sort -r fileA.txt 
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_rPjRxej0KjNH1pYdSBDge8spymZvDNyQJ0dgkVDKbTc7-OjyaY6HwMylfu3k7jHGZZvJYJ4kgruyzV_NLrZsqc5CZCmChtEuND2aHQjTqiGXPZYbr2vfFK2yibRUtIuuxpPqGcYAe87p/s1600/linux-lo@allicient.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_rPjRxej0KjNH1pYdSBDge8spymZvDNyQJ0dgkVDKbTc7-OjyaY6HwMylfu3k7jHGZZvJYJ4kgruyzV_NLrZsqc5CZCmChtEuND2aHQjTqiGXPZYbr2vfFK2yibRUtIuuxpPqGcYAe87p/s1600/linux-lo@allicient.png" /></a></div> 
 
16. VI Command 
 
Vi is a most popular text editor available most of the UNIX-like OS. Below examples open file in read only with -R option. Press ‘:q‘ to quit from vi window. 
 
# vi -R /etc/shadows 
 
17. SSH Command (Secure Shell) 
 
SSH command is used to login into remote host. For example the below ssh command will connect to remote host (192.168.50.2) using user as narad. 
 
# ssh narad@192.168.50.2 
 
To check the version of ssh use option -V (uppercase) shows version of ssh. 
 
# ssh -V 
 
OpenSSH_5.3p1, OpenSSL 1.0.0-fips 29 Mar 2010 
 
18. Ftp or sftp Command 
 
ftp or sftp command is used to connect to remote ftp host. ftp is (file transfer protocol) and sftp is (secure file transfer protocol). For example the below commands will connect to ftp host (192.168.50.2). 
 
# ftp 192.168.50.2 
 
# sftp 192.168.50.2 
 
Putting multiple files in remote host with mput similarly we can do mget to download multiple files from remote host. 
 
# ftp > mput *.txt 
 
# ftp > mget *.txt 
 
19. Service Command 
 
Service command call script located at /etc/init.d/ directory and execute the script. There are two ways to start the any service. For example we start the service called httpd with service command. 
 
# service httpd start 
OR 
# /etc/init.d/httpd start 
 
 
 
20. Top Command 
 
top command displays processor activity of your system and also displays tasks managed by kernel in real-time. It’ll show processor and memory are being used. Use top command with ‘u‘ option this will display specific User process details as shown below. Press ‘O‘ (uppercase letter) to sort as per desired by you. Press ‘q‘ to quit from top screen. 
 
# top -u tecmint 
 
top - 11:13:11 up  3:19,  2 users,  load average: 0.00, 0.00, 0.00 
Tasks: 116 total,   1 running, 115 sleeping,   0 stopped,   0 zombie 
Cpu(s):  0.0%us,  0.3%sy,  0.0%ni, 99.7%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st 
Mem:   1030800k total,   736188k used,   294612k free,    51760k buffers 
Swap:  2064376k total,        0k used,  2064376k free,   547704k cached 
 
PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND 
1889 tecmint   20   0 11468 1648  920 S  0.0  0.2   0:00.59 sshd 
1890 tecmint   20   0  5124 1668 1416 S  0.0  0.2   0:00.44 bash 
6698 tecmint   20   0 11600 1668  924 S  0.0  0.2   0:01.19 sshd 
6699 tecmint   20   0  5124 1596 1352 S  0.0  0.2   0:00.11 bash 
 
21. Tar Command 
 
tar command is used to compress files and folders in Linux. For example the below command will create a archive for /home directory with file name as archive-name.tar. 
 
# tar -cvf archive-name.tar /home 
 
To extract tar archive file use the option as follows. 
 
# tar -xvf archive-name.tar 
 
22. Grep Command 
 
grep search for a given string in a file. Only tecmint user displays from /etc/passwd file. we can use -i option for ignoring case sensitive. 
 
# grep tecmint /etc/passwd 
 
tecmint:x:500:500::/home/tecmint:/bin/bash 
 
23. Find Command 
 
Find command used to search files, strings and directories. The below example of find command search tecmint word in ‘/‘ partition and return the output. 
 
# find / -name tecmint 
 
/var/spool/mail/tecmint 
/home/tecmint 
/root/home/tecmint 
 
24. lsof Command 
 
lsof mean List of all open files. Below lsof command list of all opened files by user tecmint. 
 
# lsof -u tecmint 
 
COMMAND  PID    USER   FD   TYPE     DEVICE SIZE/OFF   NODE NAME 
sshd    1889 tecmint  cwd    DIR      253,0     4096      2 / 
sshd    1889 tecmint   txt      REG      253,0    532336 298069 /usr/sbin/sshd 
sshd    1889 tecmint  DEL    REG      253,0          412940 /lib/libcom_err.so.2.1 
sshd    1889 tecmint  DEL    REG      253,0          393156 /lib/ld-2.12.so 
sshd    1889 tecmint  DEL    REG      253,0          298643 /usr/lib/libcrypto.so.1.0.0 
sshd    1889 tecmint  DEL    REG      253,0          393173 /lib/libnsl-2.12.so 
sshd    1889 tecmint  DEL    REG      253,0          412937 /lib/libkrb5support.so.0.1 
sshd    1889 tecmint  DEL    REG      253,0          412961 /lib/libplc4.so 
 
 
25. ps command 
 
ps command displays about processes running in the system. Below example show init process only. 
 
# ps -ef | grep init 
 
root         1     0  0 07:53 ?        00:00:04 /sbin/init 
root      7508  6825  0 11:48 pts/1    00:00:00 grep init 
 
26. kill command 
Use kill command to terminate process. First find process id with ps command as shown below and kill process with kill -9 command. 
 
# ps -ef | grep init 
root         1     0  0 07:53 ?        00:00:04 /sbin/init 
root      7508  6825  0 11:48 pts/1    00:00:00 grep init 
 
# kill- 9 7508 
 
27. rm command 
 
rm command used to remove or delete a file without prompting for confirmation. 
 
# rm filename 
 
Using -i option to get confirmation before removing it. Using options ‘-r‘ and ‘-f‘ will remove the file forcefully without confirmation. 
 
# rm -i test.txt 
 
rm: remove regular file `test.txt'? 
 
28. mkdir command example. 
 
mkdir command is used to create directories under Linux. 
 
# mkdir directoryname 
 
</div>

Linux Commands for System Administrators

1. Uptime Command In Linux uptime command shows since how long your system is running and the number of users are currently logged in and a...

CSS Media Queries for Standard Devices

Unknown 0 HTML and CSS 10:00

<div dir="ltr" style="text-align: left;" trbidi="on">Here are the some commonly used  CSS Media Queries for devices like iphone , ipad, android tablets etc… 
<pre class="brush:html">/* Smartphones (portrait and landscape) ———– */
@media only screen
and (min-device-width : 320px)
and (max-device-width : 480px) {
/* Styles */
}

/* Smartphones (landscape) ———– */
@media only screen
and (min-width : 321px) {
/* Styles */
}

/* Smartphones (portrait) ———– */
@media only screen
and (max-width : 320px) {
/* Styles */
}

/* iPads (portrait and landscape) ———– */
@media only screen
and (min-device-width : 768px)
and (max-device-width : 1024px) {
/* Styles */
}

/* iPads (landscape) ———– */
@media only screen
and (min-device-width : 768px)
and (max-device-width : 1024px)
and (orientation : landscape) {
/* Styles */
}
/* iPads (portrait) ———– */
@media only screen
and (min-device-width : 768px)
and (max-device-width : 1024px)
and (orientation : portrait) {
/* Styles */
}

/* Desktops and laptops ———– */
@media only screen
and (min-width : 1224px) {
/* Styles */
}

/* Large screens ———– */
@media only screen
and (min-width : 1824px) {
/* Styles */
}

/* iPhone 4 ———– */
@media
only screen and (-webkit-min-device-pixel-ratio : 1.5),
only screen and (min-device-pixel-ratio : 1.5) {
/* Styles */
}
</pre></div>

CSS Media Queries for Standard Devices

Here are the some commonly used CSS Media Queries for devices like iphone , ipad, android tablets etc… /* Smartphones (portrait and landsc...

Windows 10 Technical Preview

Unknown 0 Softwares and Utilities 23:21

<div dir="ltr" style="text-align: left;" trbidi="on"><div style="text-align: justify;">Microsoft only unveiled Windows 10 to the world yesterday, but you can already download a preview version of the new operating system today. The Windows 10 Technical Preview is designed for enthusiasts, developers, and enterprise customers to evaluate the latest changes to Windows. Microsoft has created a special insiders program to deliver regular updates throughout the Windows 10 development cycle, and those who sign up will get the very latest software to test. 
 
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6T96MQm2GkUG76Q1TLNEjAlJsV7Q20uasLAYdMd7P1X9qaB-mGVZh1pnFxgJlEAIajSvOZWqXma0DqmGljCsLD8RwbyhyphenhyphenRtBMTiZpU7CkNc3S4xv_BISvWBH03spG7L2dkcdY__Cvlf_o/s1600/windows_10_startmenu_cropped.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="228" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6T96MQm2GkUG76Q1TLNEjAlJsV7Q20uasLAYdMd7P1X9qaB-mGVZh1pnFxgJlEAIajSvOZWqXma0DqmGljCsLD8RwbyhyphenhyphenRtBMTiZpU7CkNc3S4xv_BISvWBH03spG7L2dkcdY__Cvlf_o/s1600/windows_10_startmenu_cropped.jpg" width="320" /></a></div></div><div style="text-align: justify;"> 
</div><div style="text-align: justify;">It’s an unusual move for Microsoft, but one that it plans to capitalize on by looking closely at feedback from those who opt to install the early version of Windows 10. Microsoft is releasing Windows 10 Technical Preview as an ISO download, meaning you can install it in a virtual machine, clean install the OS on a spare machine, or even attempt to upgrade your existing Windows 8.1 installation. It’s a very early build of Windows 10 so there will be bugs, but if you’re interested in testing the very latest version of Windows then Microsoft’s preview site has all the details for downloading and installing Windows 10.</div> 
<div class="separator" style="clear: both; text-align: center;"><a href="http://iso.esd.microsoft.com/W9TPI/FD54DF81A4CCF4511BA1445C606DDBA2/WindowsTechnicalPreview-x86-EN-US.iso" target="_blank"><img alt="http://iso.esd.microsoft.com/W9TPI/FD54DF81A4CCF4511BA1445C606DDBA2/WindowsTechnicalPreview-x86-EN-US.iso" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUHb3klGOpIdpZlFy45DqPAlnqtZG1M1QypumPemSjxlGxySO2hOpmgl_q0Q6cwjbkoP3129htHMgs3SMrHbUlHaMwHj_Tz-4hPp6z5nmUCx7WvaJa2n9edwEqtoyGXicIteqT1QgjF2_b/s1600/download_icon_86.png" title="Download_now" /></a><a href="http://iso.esd.microsoft.com/W9TPI/FD54DF81A4CCF4511BA1445C606DDBA2/WindowsTechnicalPreview-x64-EN-US.iso" target="_blank"><img alt="Download_now" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjz87ZTsawCB0fnzO-OEXnP_ybbNNifzoh-hnmzUZ-VLd_PllZ_EgE77_fQv4iCLTTUUQ6OYxpMnJj5_n_gPELe3f8MtENZrI_TI-nex1DPLY457qGMYQByRklLOFeOHRgIttf_LwTUUhcJ/s1600/download_icon_64.png" /></a></div> 
</div>

Windows 10 Technical Preview

Microsoft only unveiled Windows 10 to the world yesterday, but you can already download a preview version of the new operating system today....

Windows 9 Pro Full Eng x64

Unknown 1 Softwares and Utilities 23:10

<div dir="ltr" style="text-align: left;" trbidi="on">
Download Windows 9 Pro Full Eng x64 (Single Link) iSO 2014 With Product Key –  Windows 9 the latest edition windows that will be published by microsoft is this one. The newest & more power up when we compare with windows 8.1 edition. 
<div class="separator" style="clear: both; text-align: center;">
</div>
 
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCraKek0eoiCGIsgcl0Qz9W_3sdGCRvE6PL34khD2PBykanPDtLE6fyxysLPHfo3e3oORHq5-6PDJzNRR4tf33uaDRnaC0UJ1ahIRFd6ecnv9YxO1EPPa4OnU8UZEuIkn2TPlyjaRNK3fY/s1600/Windows+9+Professional+(Eng%2Bx64%2BSingle%2BLink)%2BMay%2B2014.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCraKek0eoiCGIsgcl0Qz9W_3sdGCRvE6PL34khD2PBykanPDtLE6fyxysLPHfo3e3oORHq5-6PDJzNRR4tf33uaDRnaC0UJ1ahIRFd6ecnv9YxO1EPPa4OnU8UZEuIkn2TPlyjaRNK3fY/s1600/Windows+9+Professional+(Eng%2Bx64%2BSingle%2BLink)%2BMay%2B2014.png" width="320" /></a></div>
 
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjI7Rfy3_bAO00XEaduOxKPm2lEcoD-ykPunGs907epJyvCmVyQr6erW4_QcmYrzG7Mxn1VY6qRA3LXDngLiAp1DzXsQwuYOAsRpa9XDh84TIaOA2rZJ_BRqDF3x3YBuc303cnxSPp4-T9l/s1600/Windows+9+Professional+Dekstop+Eng+x64+Single+Link)%2BMay%2B2014.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjI7Rfy3_bAO00XEaduOxKPm2lEcoD-ykPunGs907epJyvCmVyQr6erW4_QcmYrzG7Mxn1VY6qRA3LXDngLiAp1DzXsQwuYOAsRpa9XDh84TIaOA2rZJ_BRqDF3x3YBuc303cnxSPp4-T9l/s1600/Windows+9+Professional+Dekstop+Eng+x64+Single+Link)%2BMay%2B2014.png" width="320" /></a></div>
 
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4H7FJvbql3FPxJLOAiAWWW_VPzewE2lUyoWczsFypCTjaVUeA2PMJUGq2ZDS1O3uyrcgcYOKuXgi0V11bGlJKRhZg69XOZQrm8NzyIju1kZTMgZSjxnKZUS2BhzZc4Q_fggzAudUAnQlf/s1600/Windows+9+Professional+Install+Language+(Eng%2Bx64%2BSingle%2BLink)%2BMay%2B2014.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4H7FJvbql3FPxJLOAiAWWW_VPzewE2lUyoWczsFypCTjaVUeA2PMJUGq2ZDS1O3uyrcgcYOKuXgi0V11bGlJKRhZg69XOZQrm8NzyIju1kZTMgZSjxnKZUS2BhzZc4Q_fggzAudUAnQlf/s1600/Windows+9+Professional+Install+Language+(Eng%2Bx64%2BSingle%2BLink)%2BMay%2B2014.png" width="320" /> </a></div>
<div class="separator" style="clear: both; text-align: center;">
 </div>
<div id="stcpDiv" style="left: -1988px; position: absolute; top: -1999px;">
<div>
Windows 9 Pro 2014 Download Full Version</div>
<div>
  Version : Professional</div>
<div>
 Languange : English</div>
<div>
  Type File : Rar/ISO</div>
<div>
 Code File : 9pro.may2014</div>
<div>
 Password : No</div>
<div>
Medicine : Include – PreActivated</div>
<div>
 OS Support : Win 9 x64 Bit</div>
<div>
 Updated : 6 Mei 2014</div>
<div>
 Publisher : Microsoft/MOD</div>
<div>
Software included: </div>
<div>
Bit Torrent 7.8.2 Build 30417, CCleaner Professional 4.08.4428</div>
<div>
CPU-Z 1.68, Adobe Flash Player ActiveX 12, Internet Download Manager 6.12 Final, .NET Framework Version AIO, K-Lite Codec Pack 10.15 (Full), Ultra ISO 9.8.1, USB Disk Security 6.2.0.432, Team Viewer 9, USB Safely Remove 5.2 Final, VLC, Media Player 2.1.3, Visual C++ 2008 SP1 Redis, Microsoft Silverlight 5.1.10411.0 Final x64, Java Runtime Environment 1.7.0.45, Visual C++ 2005 Redis, Visual C++ 2005 SP1_Redis, Winrar 5.0, Visual C++ 2010 Redis, Visual C++ 2012 Redis, Visual C++ 2008 Redis, Aimp Player 3.55, Adobe Reader 11.4, Adobe Flash Player 12.0.235, Autorun Virus Remover v3.3, Boot Screen Win9 By DiLshad Sys, Firefox 28 Final, Glary Utilities 4, DirectX32, FileZilla FileZilla 3.8.0, Notepad++ 6.5, Skype 6.11.0.102, GOM Player 2.2.57.5189, Hotspot Shield 3.37, Internet Explorer 11 Final X64.</div>
- See more at: http://localhost:81/test/download-windows-9-pro-full-eng-x64/#sthash.Xam1thVb.dpuf</div>
<div class="separator" style="clear: both; text-align: justify;">
Windows 9 Pro 2014 Download Full Version</div>
  Version : Professional 
 Languange : English 
  Type File : Rar/ISO 
 Code File : 9pro.may2014 
 Password : No 
Medicine : Include – PreActivated 
 OS Support : Win 9 x64 Bit 
 Updated : 6 Mei 2014 
 Publisher : Microsoft/MOD 
Software included: 
Bit Torrent 7.8.2 Build 30417, CCleaner Professional 4.08.4428 
CPU-Z 1.68, Adobe Flash Player ActiveX 12, Internet Download Manager 6.12 Final, .NET Framework Version AIO, K-Lite Codec Pack 10.15 (Full), Ultra ISO 9.8.1, USB Disk Security 6.2.0.432, Team Viewer 9, USB Safely Remove 5.2 Final, VLC, Media Player 2.1.3, Visual C++ 2008 SP1 Redis, Microsoft Silverlight 5.1.10411.0 Final x64, Java Runtime Environment 1.7.0.45, Visual C++ 2005 Redis, Visual C++ 2005 SP1_Redis, Winrar 5.0, Visual C++ 2010 Redis, Visual C++ 2012 Redis, Visual C++ 2008 Redis, Aimp Player 3.55, Adobe Reader 11.4, Adobe Flash Player 12.0.235, Autorun Virus Remover v3.3, Boot Screen Win9 By DiLshad Sys, Firefox 28 Final, Glary Utilities 4, DirectX32, FileZilla FileZilla 3.8.0, Notepad++ 6.5, Skype 6.11.0.102, GOM Player 2.2.57.5189, Hotspot Shield 3.37, Internet Explorer 11 Final X64. 
<div class="separator" style="clear: both; text-align: center;">
<a href="http://turbobit.net/download/free/onya21k7c6b1" target="_blank"><img alt="http://turbobit.net/download/free/onya21k7c6b1" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjz87ZTsawCB0fnzO-OEXnP_ybbNNifzoh-hnmzUZ-VLd_PllZ_EgE77_fQv4iCLTTUUQ6OYxpMnJj5_n_gPELe3f8MtENZrI_TI-nex1DPLY457qGMYQByRklLOFeOHRgIttf_LwTUUhcJ/s1600/download_icon_64.png" /></a></div>
<div class="separator" style="clear: both; text-align: justify;">
 </div>
<div id="stcpDiv" style="left: -1988px; position: absolute; top: -1999px;">
Download Windows 9 Pro Full Eng x64 (Single Link) iSO 2014 With Product Key –  Windows 9 the latest edition windows that will be published by microsoft is this one. The newest & more power up when we compare with windows 8.1 edition. - See more at: http://localhost:81/test/download-windows-9-pro-full-eng-x64/#sthash.Xam1thVb.dpuf 
<div id="stcpDiv" style="left: -1988px; position: absolute; top: -1999px;">
Download Windows 9 Pro Full Eng x64 (Single Link) iSO 2014 With Product Key –  Windows 9 the latest edition windows that will be published by microsoft is this one. The newest & more power up when we compare with windows 8.1 edition. - See more at: http://localhost:81/test/download-windows-9-pro-full-eng-x64/#sthash.Xam1thVb.dpuf</div>
</div>
</div>

Windows 9 Pro Full Eng x64

Download Windows 9 Pro Full Eng x64 (Single Link) iSO 2014 With Product Key – Windows 9 the latest edition windows that will be published ...

Importaint Concepts in SAD

Unknown 0 B.Tech, SAD 22:28

<div dir="ltr" style="text-align: left;" trbidi="on"><ul style="text-align: justify;"><li>Role Of System Analyst :-The Systems Analyst is an “IT Business Analyst” who is more focused on system design and the technical aspects of the solution. The systems analyst’s role is mostly system solution centric (does not generally participate in the requirements gathering process) and is involved in the creation of functional and technical specifications. This is the professional who, once requirements are clearly defined, creates the functional solution and, by working with the technical team (architect and developers), creates technical specifications and designs. 
Other common titles for this role are: Systems Engineer, Business Analyst (generic term), etc.</li>
<li>Quality Control :-1. Quality Control is concerned with the software product being developed. It measures and controls the quality of the software as it is being developed. 
2. Quality control system provides routine checks to ensure that the software is being developed correctly without errors. 
3. The Quality Control system identifies and addresses product errors/defects. 
4. Quality Control ensures that the final product is error free and satisfactory. 
5. Quality Control (QC) can also be referred as testing activity.</li>
<li>Main Importance of feasibility study in Software Development :-         The aim of a feasibility study is to see whether it is possible to develop a system at a reasonable cost. At the end of the feasibility study a decision is taken whether to proceed or not. A feasibility study contains the general requirements of the proposed system. 
Let us consider the task of setting up an Information System for a nursery and seeing how Information Technology can help it run more efficiently.  </li>
<li>Audit Trail:- <div class="pos" id="a167:392Z7p1">An audit trail is a logical record of computer activities/usage/processing pertaining to an operating</div><div class="pos" id="a167:412Z9p1">or application system or user activities. An information system may have several audit trails, each</div><div class="pos" id="a167:432Z11p1">devoted to a particular type of activity. All these audit trails are primarily extracted from the audit</div><div class="pos" id="a167:452Z13p1">log recorded on chronological basis. The audit log is maintained only for the list of activities</div><div class="pos" id="a167:473Z15p1">specified for which the log is to be maintained. The information can be recorded varies including</div><div class="pos" id="a167:493Z17p1">but not limited to</div><div class="pos" id="a194:513Z19p1">1. Time stamp for the log in/out time</div><div class="pos" id="a194:533Z21p1">2. Terminal in use</div><div class="pos" id="a194:554Z23p1">3. Files accessed</div><div class="pos" id="a194:574Z25p1">4. Transactions performed</div><div class="pos" id="a194:594Z27p1">5. Amendments made</div><div class="pos" id="a167:635Z29p1">Audit trails can provide a means to help accomplish several security-related objectives, including</div><div class="pos" id="a167:655Z31p1">individual accountability, reconstruction of events (actions that happen on a computer system),</div><div class="pos" id="a167:675Z33p1">intrusion detection, and problem analysis, as well as evidence of the correct processing regimes</div><div class="pos" id="a167:695Z35p1">within a system. 
 
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRTfUZvpIT-SdXeWOOa0ZLoi25q6MfovFasxYdBiURwYHcI3YRCpFsa-W1WEy9BnJIcr_TnLnrarPWjlOXzltsNfcApI6HHc1ueJFRcF4kCSYG8OflQep7pIrNalRsSMtAkaoO-AnyaPde/s1600/sad.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="258" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRTfUZvpIT-SdXeWOOa0ZLoi25q6MfovFasxYdBiURwYHcI3YRCpFsa-W1WEy9BnJIcr_TnLnrarPWjlOXzltsNfcApI6HHc1ueJFRcF4kCSYG8OflQep7pIrNalRsSMtAkaoO-AnyaPde/s1600/sad.png" width="320" /></a></div> 
</div></li>
<li>Various Types of threats in computer system:- 1. Trojan. Trojan is one of the most complicated threats among all. Most of the popular banking threats come from the Trojan family such as Zeus and SpyEye. It has the ability to hide itself from antivirus detection and steal important banking data to compromise your bank account. If the Trojan is really powerful, it can take over your entire security system as well. As a result, a Trojan can cause many types of damage starting from your own computer to your online account. 2. Virus. Looking at the technology 10 years back, Virus is something really popular. It is a malicious program where it replicates itself and aim to only destroy a computer. The ultimate goal of a virus is to ensure that the victim’s computer will never be able to operate properly or even at all. It is not so popular today because Malware today is designed to earn money over destruction. As a result, Virus is only available for people who want to use it for some sort of revenge purpose. 
3. Worms. One of the most harmless threats where it is program designed only to spread. It does not alter your system to cause you to have a nightmare with your computer, but it can spread from one computer to another computer within a network or even the internet. The computer security risk here is, it will use up your computer hard disk space due to the replication and took up most of your bandwidth due to the spread. 
4. Spyware. Is a Malware which is designed to spy on the victim’s computer. If you are infected with it, probably your daily activity or certain activity will be spied by the spyware and it will find itself a way to contact the host of this malware. Mostly, the use of this spyware is to know what your daily activity is so that the attacker can make use of your information. Such as if you browse on sex toys for a week every day, the attacker will try to come out with a sex toy scam to cheat on your money. 
5. Scareware. Scareware is something that plant into your system and immediately inform you that you have hundreds of infections which you don’t have. The idea here is to trick you into purchasing a bogus anti-malware where it claims to remove those threats. It is all about cheating your money but the approach is a little different here because it scares you so that you will buy. 
6. Keylogger. Something that keeps a record of every keystroke you made on your keyboard. Keylogger is a very powerful threat to steal people’s login credential such as username and password. It is also usually a sub-function of a powerful Trojan. 
7. Adware. Is a form of threat where your computer will start popping out a lot of advertisement. It can be from non-adult materials to adult materials because any ads will make the host some money. It is not really harmful threat but can be pretty annoying.</li>
</ul></div>

Importaint Concepts in SAD

Role Of System Analyst :- The Systems Analyst is an “IT Business Analyst” who is more focused on system design and the technical aspects of ...