Posts

Showing posts from 2009

Common Unix - Shell Features

Overview of common shell features. 
The following features are standard in every shell. List is as follows -
Command     Meaning
>     Redirect output
>>     Append to file
<     Redirect input
<<     "Here" document (redirect input)
| Pipe     output
&     Run process in background.
;     Separate commands on same line
*     Match any character(s) in filename
?     Match single character in filename
[ ]     Match any characters enclosed
( )     Execute in subshell
` `     Substitute output of enclosed command
" "     Partial quote (allows variable and command expansion)
' '     Full quote (no expansion)
\     Quote following character
$var     Use value for variable
$$     Process id
$0     Command name
$n     nth argument (n from 0 to 9)
$*     All arguments as a simple word
#     Begin comment
bg     Background execution
break     Break from loop statements
cd     Change directories
continue     Resume a program loop
echo     Display output
eval     Evaluate ar…

Writing Recursive Functions

How to Write Recursive Functions A recursive procedure is one that calls itself. Example is as follows – The following procedure uses recursion to calculate the factorial of its original argument. Function factorial(ByVal n As Integer) As Integer
If n <= 1 Then
Return 1
Else
Return factorial(n – 1) * n
End If
End Function

UNIX Commands in Nutshell

UNIX Command Summary There are MANY commands available for you in a UNIX shell account. A list of them follows (in no particular order). Remember, you can always read the manpage on each command for more information. ls …………….. show directory, in alphabetical order
logout …………. logs off system
mkdir ………….. make a directory
rmdir ………….. remove directory (rm -r to delete folders with files)
rm …………….. remove files
cd …………….. change current directory
man (command) …… shows help on a specific command
talk (user) …….. pages user for chat – (user) is a email address
write (user) ……. write a user on the local system (control-c to end) pico (filename) …. easy to use text editor to edit files
pine …………… easy to use mailer
more (file) …….. views a file, pausing every screenful sz …………….. send a file (to you) using zmodem
rz …………….. recieve a file (to the unix system) using zmodem telnet (host) …… connect to another Internet site
ftp (host) ……… connects to a FTP site
archie (filename) .. se…