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Full Discussion: For loop statement - catch error
Top Forums Shell Programming and Scripting For loop statement - catch error Post 302136760 by cfajohnson on Wednesday 19th of September 2007 02:37:55 PM
Old 09-19-2007
Quote:
Originally Posted by lumdev
I'm having a question about for loops. (bash)

I have the following for example:

for file in `ls *.txt`

That is not the way to loop through files. Not only is ls unnecessary, it will break your script if any filenames contain spaces or other pathological characters. Use the wildcard directly:

Code:
for file in *.txt

Quote:
do
read file ...
done

Now when there is a file present there is no problem, now when there is no file present I get the following output in my standard mail box : "No such file or directory" Script is executed via crontab.

Now I want to catch the above error so I don't get it in my mail any more, but I have no idea how to do this.

I can make an if statement first "if [ -f *.txt ] ...", but there must be a better solution.

No, you cannot do that; it will fail if there is more than one .txt file.

You can use a function:

Code:
is_file() {
   test -f "$1"
}

is_file *.txt &&
 for file in *.txt
 do
   ...
 done

The safest way is to check each file:

Code:
for file in *.txt
do
  [ -f "$file" ] || continue
  ...
done

 

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LEARN ABOUT CENTOS

locale::script

Locale::Script(3)					User Contributed Perl Documentation					 Locale::Script(3)

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) 2010-2013 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							    2013-06-03							 Locale::Script(3)
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