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Full Discussion: Single UNIX command to display users and to count them
Top Forums UNIX for Dummies Questions & Answers Single UNIX command to display users and to count them Post 302739569 by sreyan32 on Tuesday 4th of December 2012 11:55:29 AM
Old 12-04-2012
Question
Quote:
Originally Posted by bakunin

Code:
$(( $(w| wc -l) - 2 ))

bakunin
Thank You so much for your detailed explanation. But I have some doubts-:

1) In the following code-:

Code:
$(( $(w| wc -l) - 2 ))

Why have you used two opening and two closing brackets for the outer expression and only one opening and one closing for the inner expression that is-:

Code:
$(w| wc -l)

I tried it with two opening and closing brackets for both inner and outer expression and I keep getting errors. Same thing if I try with one bracket for both inner and outer expressions.Why does it only work like the way that you have specified ?

2) When we use tee the stream is duplicated and by default the first stream is always printed out. Am I right in assuming this ? Or is there a way to control the output of both the divided streams?

3)The duplicate stream that tee creates is also an output stream. And we redirect that second duplicate stream to the following operations-:

Code:
(cut -d\  -f1|uniq | wc -l >/dev/stderr )

But then if there is already an output stream then why are we redirecting the output to the error stream ?

By the way do you know what the following command does-:

Code:
kill $!

I searched for it in Google but I did not get any such answer. I just don't want to open up another thread for only such a small topic. If you do know the answer then please let me know.

Thank You again for your explanation. It did help a lot.
 

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LEARN ABOUT CENTOS

locale::codes::langext

Locale::Codes::LangExt(3)				User Contributed Perl Documentation				 Locale::Codes::LangExt(3)

NAME

       Locale::Codes::LangExt - standard codes for language extension identification

SYNOPSIS

	  use Locale::Codes::LangExt;

	  $lext = code2langext('acm');		       # $lext gets 'Mesopotamian Arabic'
	  $code = langext2code('Mesopotamian Arabic'); # $code gets 'acm'

	  @codes   = all_langext_codes();
	  @names   = all_langext_names();

DESCRIPTION

       The "Locale::Codes::LangExt" module provides access to standard codes used for identifying language extensions, such as those as defined in
       the IANA language registry.

       Most of the routines take an optional additional argument which specifies the code set to use. If not specified, the default IANA language
       registry codes will be used.

SUPPORTED CODE SETS

       There are several different code sets you can use for identifying language extensions. 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:

	  $lext = code2langext('acm','alpha');
	  $lext = code2langext('acm',LOCALE_LANGEXT_ALPHA);

       The codesets currently supported are:

       alpha
	   This is the set of three-letter (lowercase) codes from the IANA language registry, such as 'acm' for Mesopotamian Arabic.

	   This is the default code set.

ROUTINES

       code2langext ( CODE [,CODESET] )
       langext2code ( NAME [,CODESET] )
       langext_code2code ( CODE ,CODESET ,CODESET2 )
       all_langext_codes ( [CODESET] )
       all_langext_names ( [CODESET] )
       Locale::Codes::LangExt::rename_langext  ( CODE ,NEW_NAME [,CODESET] )
       Locale::Codes::LangExt::add_langext  ( CODE ,NAME [,CODESET] )
       Locale::Codes::LangExt::delete_langext  ( CODE [,CODESET] )
       Locale::Codes::LangExt::add_langext_alias  ( NAME ,NEW_NAME )
       Locale::Codes::LangExt::delete_langext_alias  ( NAME )
       Locale::Codes::LangExt::rename_langext_code  ( CODE ,NEW_CODE [,CODESET] )
       Locale::Codes::LangExt::add_langext_code_alias  ( CODE ,NEW_CODE [,CODESET] )
       Locale::Codes::LangExt::delete_langext_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.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) 2011-2013 Sullivan Beck

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

perl v5.16.3							    2013-02-27						 Locale::Codes::LangExt(3)
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