The implementation of the Shell programming help function

A program that often needs help explaining.
The ways to activate help instructions are described in two ways
1. The simplest way is to discriminate by the number of parameters. For example, displays the help description without any parameters.
2. The normal practice is that the command line is followed by the-h parameter.
Shell help can be written using a bunch of ECHO commands to output to the console, and better
Here Doc syntax, which shows that the document is neatly formatted and consistent with the output. Not a bunch of echoes and double quotes.
Here's an example:

1. Simple method
#!/bin/bash-
Set-o Nounset # Treat unset variables as an error
Help ()
{
Cat <<-EOF
DESC: This program is used to ....
Usage:./1.sh <filename>
Author:hjjdebug
License: ...
Eof
Exit 0
}
If [$#-lt 1] # cannot be used < Here is a numeric comparison, not a string comparison
Then
Help
Fi

2. Formal Methods
#!/bin/bash-
#set-o nounset # This option is off, otherwise it is not defined by the syntax error. Affect vision.
Help ()
{
Cat <<-EOF
DESC: This program is used to ....
Usage:./1.sh <filename>
Author:hjjdebug
License: ...
Eof
Exit 0
}

#这里通过判断 the existence of a discriminant, or through $ #判别, shift will change the value of both,
While [-N "$"]; Do
Case $ in
-h) help;; # function Help is called
--) Shift;break; # End of options
-*) echo "error:no such option $."; Exit 1;;
*) break;;
Esac
Done