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UNIX 3 - Coggle Diagram
UNIX 3
Command line structure
command options arguments
command options options
command options- options- options
Creating new commands
$echo pwd > sample
$cat sample
$sh < sample
Shell variables
SYSTEM
PATH
Holds a list of directories with :
HOME
Value of path of home dir
IFS
Space , tab , newline
MAIL
Value for where user's mail is kept
SHELL
Absolute path for user's shell program
TERM
Type of terminal
LOCAL
Rules
Alphanumeric
_
case sensitive
Defining
$var1
Read only
readonly() _ Kinda like constants
More on I/O Redirection
< Input redirection
Greater than > Output redirection
Two greater thans Output redirection with appending
Looping in shell programs
while
while condition is true
do
set of commands
done
until
until condition is false
do
Set of commands
done
for
for var in list
do
set of commands
done
Meta chars
Asterisk* , - , [ ] , ?
Using the shell command line
Command arguments and parameters
Program output as aruments