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Full Discussion: Read the line from the last and display the one which is non-zero
Top Forums UNIX for Dummies Questions & Answers Read the line from the last and display the one which is non-zero Post 302935978 by Don Cragun on Saturday 21st of February 2015 01:31:54 AM
Old 02-21-2015
Quote:
Originally Posted by hariniiyer300
Hi All,

My requirement is this. Am trying to find a one liner unix command, which will check the last line of the file for 0. If it is zero, it would pick the previous line, else it should display the last line.

Eg:
Code:
abcd
efgh
ijhk
0
0

Output expected -- ijhk

Please share your ideas.

Thanks.
I am glad that you have code that does what you want. But, it does not do what you requested. You said that if the last line is 0, it should print the previous line. The previous line is the next to the last line of the file (which also contains 0; not ijhk which is the next to the next to the last line).

Code that seems to do what you requested, even though it is not what you apparently want, is:
Code:
tail -n 2 file | (
	read -r prev
	read -r last
	if [ "$last" = '0' ]
	then	printf '%s\n' "$prev"
	else	printf '%s\n' "$last"
	fi
)

or as a 1-liner:
Code:
tail -n2 file|(read -r prev;read -r last;[ "$last" = '0' ]&&printf '%s\n' "$prev"||printf '%s\n' "$last")

If your system has a really old version of the tail (and it doesn't support a -n option, change the:
Code:
tail -n2 file

in either script to:
Code:
tail -2 file

Note that either of these scripts will give you an empty line of output if your input file doesn't contain at least two lines. Your problem statement didn't say anything about what should happen if there are less than two lines in your input file.
 

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LEARN ABOUT DEBIAN

locale::script

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

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. The ones currently supported are:

       alpha
	   This is a set of four-letter (capitalized) codes from ISO 15924 such as 'Phnx' for Phoenician.

	   This code set is identified with the symbol "LOCALE_SCRIPT_ALPHA".

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

	   This is the default code set.

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

	   This code set is identified with the symbol "LOCALE_SCRIPT_NUMERIC".

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 man page.

SEE ALSO

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

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) 2010-2011 Sullivan Beck

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

perl v5.14.2							    2011-09-26						     Locale::Script(3perl)
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