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Full Discussion: Using menu driven script
Top Forums Shell Programming and Scripting Using menu driven script Post 303012236 by drysdalk on Thursday 1st of February 2018 03:27:42 AM
Old 02-01-2018
Hi,

If you are really, truly needing to provide some way for your end users in a production environment to add or subtract numbers at the command line, there's no sense in re-inventing the wheel here. UNIX already provides a fair number of ways to do this, the easiest of which is the bc utility.

It can be run interactively, like so:

Code:
$ bc
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'.
2+2
4
4-2
2
$

Or you can pipe things into it:

Code:
$ echo 2+2 | bc
4
$ echo 4-2 | bc
2
$

Or it can read its input from a file:

Code:
$ cat calc.txt
2+2
4-2
$ bc < calc.txt
4
2
$

and so on and so forth. It really would be a complete waste of your own time to write a shell script specifically to do calculation, when UNIX provides a built-in utility for doing precisely this.

Now, if this is a homework assignment (and personally, I really can't see any reason why you'd need to write a script like this outside of academia) that's absolutely fine - honestly, we really don't mind, and are always happy to help. But you would need to follow the homework rules as mentioned by Don Cragun, and as outlined here.

Alternatively, if there's some truly bizarre and currently-unimaginable reason why you absolutely MUST write such a script in a production environment, please let us know exactly what that is and I'm sure we can help. But honestly, bc is such a better answer than anything any one person could ever write a shell script to replace. Your users' own desktop OS calculator applet would be a better answer, to be frank.

Hope this helps.
This User Gave Thanks to drysdalk For This Post:
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LEARN ABOUT OSX

locale::script

Locale::Script(3pm)					 Perl Programmers Reference Guide				       Locale::Script(3pm)

NAME

       Locale::Script - standard codes for script identification

SYNOPSIS

	  use Locale::Script;

	  $script  = code2script('phnx');		      # 'Phoenician'
	  $code    = script2code('Phoenician'); 	      # 'Phnx'
	  $code    = script2code('Phoenician',
				 LOCALE_CODE_NUMERIC);	      # 115

	  @codes   = all_script_codes();
	  @scripts = all_script_names();

DESCRIPTION

       The "Locale::Script" module provides access to standards codes used for identifying scripts, such as those defined in ISO 15924.

       Most of the routines take an optional additional argument which specifies the code set to use. If not specified, the default ISO 15924
       four-letter codes will be used.

SUPPORTED CODE SETS

       There are several different code sets you can use for identifying scripts. A code set may be specified using either a name, or a constant
       that is automatically exported by this module.

       For example, the two are equivalent:

	  $script = code2script('phnx','alpha');
	  $script = code2script('phnx',LOCALE_SCRIPT_ALPHA);

       The codesets currently supported are:

       alpha, LOCALE_SCRIPT_ALPHA
	   This is a set of four-letter (capitalized) codes from ISO 15924 such as 'Phnx' for Phoenician.  It also includes additions to this set
	   included in the IANA language registry.

	   The Zxxx, Zyyy, and Zzzz codes are not used.

	   This is the default code set.

       num, LOCALE_SCRIPT_NUMERIC
	   This is a set of three-digit numeric codes from ISO 15924 such as 115 for Phoenician.

ROUTINES

       code2script ( CODE [,CODESET] )
       script2code ( NAME [,CODESET] )
       script_code2code ( CODE ,CODESET ,CODESET2 )
       all_script_codes ( [CODESET] )
       all_script_names ( [CODESET] )
       Locale::Script::rename_script  ( CODE ,NEW_NAME [,CODESET] )
       Locale::Script::add_script  ( CODE ,NAME [,CODESET] )
       Locale::Script::delete_script  ( CODE [,CODESET] )
       Locale::Script::add_script_alias  ( NAME ,NEW_NAME )
       Locale::Script::delete_script_alias  ( NAME )
       Locale::Script::rename_script_code  ( CODE ,NEW_CODE [,CODESET] )
       Locale::Script::add_script_code_alias  ( CODE ,NEW_CODE [,CODESET] )
       Locale::Script::delete_script_code_alias  ( CODE [,CODESET] )
	   These routines are all documented in the Locale::Codes::API man page.

SEE ALSO

       Locale::Codes
	   The Locale-Codes distribution.

       Locale::Codes::API
	   The list of functions supported by this module.

       http://www.unicode.org/iso15924/
	   Home page for ISO 15924.

       http://www.iana.org/assignments/language-subtag-registry
	   The IANA language subtag registry.

AUTHOR

       See Locale::Codes for full author history.

       Currently maintained by Sullivan Beck (sbeck@cpan.org).

COPYRIGHT

	  Copyright (c) 1997-2001 Canon Research Centre Europe (CRE).
	  Copyright (c) 2001-2010 Neil Bowers
	  Copyright (c) 2010-2012 Sullivan Beck

       This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.16.2							    2012-10-11						       Locale::Script(3pm)
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