What is X11?

X11 is a network protocol designed for Unix and similar operating systems to enable remote graphical access to applications. 

The X Window System (X11, X, and sometimes informally X-Windows) is a windowing system for bitmap displays, common on UNIX-like computer operating systems.

Ref: 
http://en.wikipedia.org/wiki/X_Window_System
http://toastytech.com/guis/remotex11.html

How to learn PC mainboard informations from cmd?

CMD> wmic baseboard get product,Manufacturer,version,serialnumber

[ADVICE] Using both of semicolon and slash characters at the same time

Please note that if you use semicolon and slash at the same time in sql queries, there will be executed as twice on the system.

e.g.
insert into mytable values (007,'Alper');
/

-- result of sql
-- 1 row inserted
-- 1 row inserted

-- do not use "/" with ";" to prevent this case.

Please note that if you use begin-end pl-sql code block, there should be ";" at the end of pl-sql block.

e.g.
begin
insert into mytable values (007,'Alper');
end;

-- result of sql
-- 1 row inserted

-- ";" should be existed in here.

How to always see authentication pop-up window in Firefox?

Open Firefox -> Enter "about:config" in url bar -> Search "network.automatic-ntlm-auth.allow-proxies" -> Change value to "false" -> Restart Firefox -> That's all.

How to define virtual drive on the system?

Only you need to run these commands in cmd.

e.g. subst v: "\\10.10.10.10\MyRemoteDirectory"

e.g. subst x: "D:\MyBackupDirectory"

to delete it;
subst v: /d

How to install/uninstall/search installed rpm package in Linux?

install rpm package:
e.g.
# rpm -Uvh jdk-1.6.0_35-fcs.i586.rpm
or
# rpm -ivh jdk-1.6.0_35-fcs.i586.rpm
(-U, upgrade -i, install –v, verbose –h gist of verbose)

uninstall rpm package:
e.g.
# rpm -ev jdk-1.6.0_35-fcs.i586.rpm

search installed rpm packages:
e.g.
$ rpm -qa | grep jdk

list the dependency of rpm packages:
# rpm -qRp jdk-1.6.0_35-fcs.i586.rpm
(-q, query -R, List package depends)

verify installed rpm package:
e.g.
# rpm -Vp jdk-1.6.0_35-fcs.i586.rpm
(-V, verify -p package name)

check state of files inside of rpm package:
e.g.
# rpm - qsp jdk-1.6.0_35-fcs.i586.rpm
(-s, state (installed, replaced or normal)

verify all installed rpm packages:
# rpm -Va
(-a, all)

How to install source package in linux?

Please follow the instructions:

e.g. sysstat-9.0.6.tar.gz installation;

Firstly, transfer the sysstat source package into your linux. 

Run these commands one by one;
-> tar -czvf sysstat-9.0.6.tar.gz
-> cd sysstat-9.0.6 then execute ./configure
-> make
-> make install

Usage of sar;
# sar 1 1000

How to find IP from url or domain address in windows?

e.g. tracert www.google.com

Tracing route to www.google.com [173.194.127.81]

How to run a program in start-up?

Please follow the instructions to define start-up program for Windows machines.

Press Windows key -> Click "All Programs" -> Right mouse click on "Startup" folder then click "Open" -> Define shortcut of the program in "Startup" folder -> Now, windows starts program as your shortcuts while starting system.

What is "hiberfil.sys" file?

hiberfil.sys file is using when system goes to hibernate mode that all your session information are stored in this file. After system goes up, system uses this file to restore your last session.

To modify size of it;
powercfg -h -size 70
(it means hiberfil.sys file size will be the half of system RAM size)
(also, percentage should be at least %50 in here)

To disable it;
powercfg -h off

If you disable it, pagefile.sys file size is same with system RAM size probably.

Reference: http://ozsoyler.blogspot.com.tr/2015/02/how-to-change-windows-swap-size.html

How to change windows swap size?

Windows uses pagefile.sys file as swap memory that you can easily manage it as you wish.

To do that, please follow the instructions;

Press Windows key -> Right click to "My Computer" -> Click to "Advanced system settings" -> Click to "Advanced" tab -> Click to "Settings" from "Performance" -> Click "Advanced" tab from "Performance Options" window -> Then, click to "Change" button -> Unselect to "Automatically manage paging file size for all drives" -> Lastly, select "Custom size" then modify "initial size" and "maximum size" according to related disk volume then click "OK"

Recommended: If you have too much RAM memory in your system (such as 32 GB RAM), you can disable pagefile.sys to accelerate your system. 

How to adjust hibernate option instead of using sleep option in advanced power options?

Please follow the instructions to adjust the hibernation.

Press Windows key and search "power options" -> Click to "Change plan settings" -> Then, click to "Change advanced power settings" -> Go to "Sleep" -> Then, "Sleep after" and change setting to "Never" -> Lastly, go to "Hibernate after" -> For example, change settings to "15 minutes" -> Anymore, if windows runs 15 minutes in standby, the system goes to "hibernation".

You may also run below commands in "cmd" to adjust your power settings according to power-saving approach.
powercfg -h on
powercfg -change standby-timeout-ac 0
powercfg -change monitor-timeout-ac 5
powercfg -change hibernate-timeout-ac 15

How to activate hibernate option in start menu?

Please follow the instructions to activate hibernate option for Windows machines.

Press Windows key and search "cmd" -> Right mouse click on "cmd" then select "Run as administrator" -> Run "powercfg -hibernate on" -> Press Windows key and search "power options" -> Click to "Change plan settings" -> Then, click to "Change advanced power settings" -> Go to "Sleep" and "Allow hybrid sleep" -> Change Settings to "Off" -> Now, you can see "Hibernate" option in start menu.

How to know the current connected user in sqlplus?

SQL> SHOW USER;

USER is "ALPER"

How to modify "sql page size"?

SQL> SET PAGESIZE 100

Anymore, there will be 100 lines for each page, after executes SQL queries.