A little help please Post: 302145626

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Top Forums Shell Programming and Scripting A little help please Post 302145626 by porter on Wednesday 14th of November 2007 09:36:26 PM

11-14-2007

Registered User

Quote:

Originally Posted by immyakram

I believe this can done by using the echo function by getting the line from $1 and then inserting it into $2 bu cant quite put my finger on it.

That is the essential nub of the problem. For instance, lastline would be a piece of cake

Code:

#!/bin/sh
echo "$1" >>"$2"

because the >> operator appends the data. But this problem says we have to put the data as a new first line.

So my solution says, okay I know what the contents of the new file should look like

Code:

echo "$1" | cat - "$2"

but that output just dissappears, so we need to put it somewhere, like a temporary file, here $$ will be used as a temporary file as it's a unique number, ie the pid of the shell.

Code:

echo "$1" | cat - "$2" >$$

but the problem says that this new output should be in the original file, so what we do is rename this temporary file to the original file name, which as a byproduct is (a) atomic (b) unlinks the original file

Code:

mv $$ $2

Does that help?

Now tell me any down sides of my solution... Smilie

porter

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locale::codes::langext5.18

Locale::Codes::LangExt(3pm)				 Perl Programmers Reference Guide			       Locale::Codes::LangExt(3pm)

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 v5.18.2							    2013-11-04					       Locale::Codes::LangExt(3pm)