Special parameters
``$#''-
This parameter, when referenced in a shell program,
contains the number of arguments with which
the shell program was invoked.
Its value can be used anywhere in the shell program.
Enter the command line,
shown in the following screen,
in the executable shell program
called get.num.
Then run the
cat
command on the file:
$ cat get.num
echo The number of arguments is: $#
$
The program simply displays the
number of arguments with which it is invoked.
For example:
$ get.num test out this program
The number of arguments is: 4
$
You can write a simple shell program
to demonstrate ``$*''.
Create a shell program called show.param
that will
echo
all the parameters.
Use the command line shown
in the following completed file:
$ cat show.param
echo The parameters for this command are: $*
$
The program show.param
will echo all the arguments you give the command.
Make show.param executable and try it
using these parameters:
Hello. How are you?
$ show.param Hello. How are you?
The parameters for this command are: Hello. How are you?
$
Notice that show.param
echoes Hello. How are you?
Now try show.param using more than
nine arguments:
$ show.param a b c d e f g h i j
The parameters for this command are: a b c d e f g h i j
$
Once again, show.param
echoes all the arguments you give.
The ``$*'' parameter can be useful
if you use filename expansion
to specify arguments to the shell command.
Use the filename expansion feature with
your show.param command.
For example, suppose you have
three files in your directory
named for the first three chapters of a book.
The show.param command
prints a list of all those files.
$ show.param chap?
The parameters for this command are: chap1 chap2 chap3
$
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Named variables
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Positional parameters
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SCO OpenServer Release 6.0.0 -- 02 June 2005