Working with the Unix OS

Introduction to Unix
* matches 0 or more characters
? matches 1 character
[ccc]
matches a set of characters
[c-c]
set contains a range of chars
ls -l [a-z]*
echo ???
cat ex[0-l]
matches all files starting with a lower case letter
matches 3 char file names
matches ex0 and exl
Filename Patterns
One exception is the dot "." character which must be explicitly matched if it is the first character.
echo *
all files except those starting with a dot character
echo .*
all files starting with a dot
Otherwise the special directory files . and .. and many other normally hidden files would match "*".
Unlike MS-DOS, all unix commands can use patterns like these to generate file names, even your own programs.
The reason is that pattern matching is built into the shell, instead of being duplicated in every program.
Argument Quoting
Often we wish to send a program which may contain some of the special characters like "*", ">", "|" or "&". How
they can we prevent the shell from interpreting these as special?
The answer is to use quoting.
There are several ways to quote characters. The first method quotes just one character and is done by preceding it
by a back-slash "\".
Example: echo Now for the \* of the show...
Outputs: Now for the * of the show...
Now the back-slash is a special character and it can be quoted using another back-slash.
Example: echo Slash me back with a \\
Outputs: Slash me back with a \
Another way to quote a string of characters is to place them inside single or double quotes.
Example: echo 'Please enter a letter: [a-z]?'
Outputs: Please enter a letter: [a-z]?
Note : In what it follows we are working at the Bourne Shell ( give the command sh in the prompt ).
Normally spaces and tabs would be separate each argument and the key would indicate the end of a
command. These special characters can also be quoted so that all characters within a quoted string would be treated
as one argument to the program
Example: echo "Line1 Outputs: Line1
Line2
Line2
Line3"
Line3
Note that when typing a multi-line quoted argument, shell will prompt you with a ">" instead of "$" to indicate that
the string is not yet complete.
Environment Variables
EDITOR=/usr/bin/vi
preferred editor
EXINIT="set redraw aw ai wm=0" vi options
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UBUNTU,SOLARIS: Not Defined using any of the shells
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
HOME=/home/users/grad0777 home directory
LOGNAME=grad0777
login name
PATH=/home/newapps/SUNWspro/bin command search path
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