Unix based Commands

.	Current directories
..	Parent directories
apropos	List commands related to keywords apropos
cat -b names.txt	names.txt is displayed and all line except the blank lines are numbered.
cat filename	To display the content of file
cat -n names.txt	names.txt is displayed and all line are numbered.
cat names.txt	names.txt is displayed without line numbering.
cat names.txt |more	names.txt is displayed one screen at a time.
cat>filename	To create new file
cd	Change directory
Chmod u+rwx
cp	Copies  a file
Cyclical Process	Working with a shell is cyclical process.
Device File	A file type that is used to represent hardware type.
Directory	A directory is simply a file that contains a table listing of files contained within it.
Diskless Client	Does not require the basic  UNIX operating system.
File permission	Read (r) ,write(w) ,execute(x) it has value as 4 ,2,1 respectively. users(u),group(g),other(o),all(a) these are the users.
Filesystem  Hierarchy Standard X'Open API	Define the location and names of critical system files and directories. Desined to standardize different versions of UNIX to make porting software products across version easier.
ls	List content of current directory
Ls –f	Identify file  types.
Ls -l	It gives a details like drwx-r—r-- 1 owner group size time..
ls –l	Displays file details in long list.
ls –la	Display hidden files.
ls –r	Reverse file order.
man	Display  onscreen help for a specific command
mkdir	Make a  new directory
mv	Move or rename a file
mv file1 file2	To rename a file1 and as file2
Named Pipe	A file type that allows one UNIX process or program to communicate with another.
Open Group	Created a list of features based on open standards that a distribution of UNIX must contain in order to carry UNIX stamp.
Open System Foundation	Created a version of UNIX to compete against UNIX System V Release 4.
POSIX	Define How system calls,interfaces, and libraries work with an operating system.
pwd	Present  working directory.
Regular File	A file type made up of different type of data.
rm	Remove a file
Rm -i file1	To remove file1 in interective mode
Rm -r file	Delete with its content
rmdir	Remove an existing directory
Server	All computer in a network connect to this computer.
Symbolic link file	A file type that is similar to shortcut in windows.
System V interface Definition	Specifies how an operating system needs to behave in order to be considered compliant with the standard.
Who	Display all terminal information
Who am I	User terminal information
Windows client	Found in network that use a mixed operating system deployment.
write username user1	For one way communication .here the user1 is  that u want to connect with u.
X terminal	Requires only the basic UNIX operating system.
X windows	X windows system provides the Translation between applications and the graphical user environment and operating system and graphical user environment .