Wildcards

The * wildcard

The character***is called a wildcard, and will match against none or more character(s) in a file (or directory) name. For example, in yourunixstuff**directory, type

% ls list*

This will list all files in the current directory starting withlist….

Try typing

% ls *list

This will list all files in the current directory ending with….list

The ? wildcard

The character?will match exactly one character.

So?ousewill match files likehouseandmouse, but notgrouse.

Try typing

% ls ?list

 Filename conventions

We should note here that a directory is merely a special type of file. So the rules and conventions for naming files apply also to directories.

In naming files, characters with special meanings such as/ * & %, should be avoided. Also, avoid using spaces within names. The safest way to name a file is to use only alphanumeric characters, that is, letters and numbers, together with _ (underscore) and . (dot).

Good filenames	Bad filenames
project.txt	project
my_big_program.c	my big program.c
fred_dave.doc	fred & dave.doc

File names conventionally start with a lower-case letter, and may end with a dot followed by a group of letters indicating the contents of the file. For example, all files consisting of C code may be named with the ending.c, for example,prog1.c. Then in order to list all files containing C code in your home directory, you need only typels *.cin that directory.

 Getting Help

On-line Manuals

There are on-line manuals which gives information about most commands. The manual pages tell you which options a particular command can take, and how each option modifies the behaviour of the command. Typeman commandto read the manual page for a particular command.

For example, to find out more about thewc(word count) command, type

% man wc

Alternatively

% whatis wc

gives a one-line description of the command, but omits any information about options etc.

Apropos

When you are not sure of the exact name of a command,

% apropos keyword

will give you the commands with keyword in their manual page header. For example, try typing

% apropos copy

Summary

Command	Meaning
*	match any number of characters
?	match one character
man command	read the online manual page for a command
whatis command	brief description of a command
apropos keyword	match commands with keyword in their man pages