Using Wildcard Characters Effectively 




  




The Unix shell interprets a number of characters in a special way. These
characters are known as  wildcard
characters. Usually these characters are used to describe
filenames or directory names. The handling of files is simplified by
using wildcard characters to match files that match particular patterns.











	
		Wildcard
	
		It means


	*
	An asterisk matches any number 
		of characters in a filename, including none.


	?
	The question mark matches any single character.


	[ ]
	Brackets enclose a set of characters, any one 
		of which may match a single character at 
		that position.


	-
	A hyphen used within [ ] denotes a range of characters.


	~
	A tilde at the beginning of a word expands to the 
		name of your home directory. If you append 
		another user's login name to the character, 
		it refers to that user's 
		home directory.
	









Here are some examples on how to use wildcard characters:











	You type
	It will


	$ cat  c*
	Displays any file whose name begins with c including the file c, if it exists.


	$ ls  *.c
	Lists all files that have a .c file extension.


	$ cp  ../xyz?  .
	Copies every file in one directory up that is four characters long and 
	begins with xyz to the current working directory. (The names will remain the same.)


	$ ls  xyz[34567]
	Lists every file that begins with xyz and has a 3, 4, 5, 6, or 7 at the end.


	$ ls  xyz[3-7]
	Does exactly the same thing as the previous example.


	$ ls  ~
	Lists your home directory.


	$ ls  ~/project
	Lists "project" directory under the home directory.











By using wildcard characters, you can pre-filter and zero-in 
the list of files and directories that you're really interested 
in.  Then, common operations can thus be performed on a group 
of common files using a single command.