1. The Shell is a command interpreter AND a program that runs other programs
for the user.  It is the shell that provides: filename expansion (wild cards)
I/O redirection, Command Pipelines, (Sub)processes to run programs and a
full fledged programming language.

2. To start a subshell explicitly, type sh. (or ksh or bash).  To start a subshell
implicitly, enclose  a unix command in parentheses. e.g. (date; pwd)
To exit from a subshell, type exit or exit [n] or <Ctrl-D>

3. Input for the shell can be saved in a text file and run at any time. Such
a file is called a shell script (program).  It is actually a set of 
unix and shell commands batched up to run without user interaction in between.

4. Ways of running shell scripts:
	(1) $ sh script parameter(s)
	(2) $ chmod +x script; script parameter(s)
			or     ./script parameter(s)
	(3) $ sh < script	# no parameters to script only

Questions? Robert Katz: rkatz@ned.highline.edu
Last Update July 30, 2002