Unix Tools - Command Line Processing

Try the following command (assumes that the file "grate_stories_of" is not exist on your system)
$ ls grate_stories_of
It will print message something like - grate_stories_of: No such file or directory.
ls is the name of an actual command and shell executed this command when you type command at shell prompt. Now it creates one more question What are commands? What happened when you type $ ls grate_stories_of ?
The first word on command line is, ls - is name of the command to be executed.
Everything else on command line is taken as arguments to this command. For e.g.
$ tail +10 myf
Name of command is tail, and the arguments are +10 and myf.
Exercise
Try to determine command and arguments from following commands
$ ls foo
$ cp y y.bak
$ mv y.bak y.okay
$ tail -10 myf
$ mail raj
$ sort -r -n myf
$ date
$ clear
Answer:

Command	No. of argument  to this command (i.e $#)	Actual Argument
ls	1	foo
cp	2	y  and   y.bak
mv	2	y.bak and  y.okay
tail	2	-10  and  myf
mail	1	raj
sort	3	-r, -n, and myf
date	0
clear	0

NOTE:
$# holds number of arguments specified on command line. And $* or $@ refer to all arguments passed to script.