====== UNIX Tutorial Four ======

===== 4.1 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
your **unixstuff** directory, type
<cli>ubuntu@ubunbtu:~/unixstuff$ ls list*</cli>
This will list all files in the current directory starting with **list....**. 

Try typing 
<cli>ubuntu@ubunbtu:~/unixstuff$ ls *list</cli>
This will list all files in the current directory ending with **....list**.


==== The ? wildcard ====
 
The character ''?'' will match exactly one character.
So **?ouse** will match files like **house** and **mouse**, but not **grouse**. 
Try typing 
<cli>ubuntu@ubunbtu:~/unixstuff$  ls ?list</cli>


===== 4.2 Filename conventions ===== 

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 type ls ***.c** in that directory. 

<note warning>**Beware**: some applications give the same name to all the output files they generate. 

For example, some compilers, unless given the appropriate option, produce compiled files named **a.out**. Should you forget to use that option, you are advised to rename the compiled file immediately, otherwise the next such file will overwrite it and it will be lost.</note> 

===== 4.3 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. Type ''man //command//'' to read the manual page for a particular command. 

For example, to find out more about the ''wc'' (word count) command, type 
<cli>ubuntu@ubuntu:~/unixstuff$ man wc</cli>

Alternatively 
<cli>ubuntu@ubuntu:~/unixstuff$ whatis wc</cli>
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, 
<cli>ubuntu@ubuntu:~/unixstuff$ apropos keyword</cli> 
will give you the commands with keyword in their manual page header. For example, try typing 
<cli>ubuntu@ubuntu:~/unixstuff$ apropos copy</cli>


===== 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| 

----

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 --- //[[C.P.Jobling@Swansea.ac.uk|Dr Chris P. Jobling]] 2007/09/21 16:46//