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Need help in decoding the following PERL code

showale
New User

Mar 11, 2013, 2:53 PM

Post #1 of 2 (110 views)

Need help in decoding the following PERL code	Can't Post

can any one help decoding following....I have it in my source code

Mainly I would like to know ,what is there within this if condition if (! /\|$/

and is it like , while <not eof > read one line from file, remove newline from that end of the line and then print that line to testdata.emp.tmp ?

perl -e 'while (<>) { if (! /\|$/ ) { chomp; } print ;}' $testdata.emp> $testdata.emp.tmp

thanks

Kenosis
User

Mar 11, 2013, 3:21 PM

Post #2 of 2 (106 views)

Re: [showale] Need help in decoding the following PERL code [In reply to]	Can't Post

This perl script's executed from the command line, reading each line of $testdata.emp and removes the end-of-record (a newline, in this case) from each line if the line doesn't end with "|". Output is directed to $testdata.emp.tmp

Here's the regex:

Code

!/\|$/  
^^^^^^ 
|||||| 
|||||+ - End match 
||||+ - End of line 
|||+ - Verticle bar's escaped (so it's not regarded as alternation) 
||+ - Escape 
|+ - Begin match 
+ - Not the case

So, the condition evaluates to true and the line is chomped if the line doesn't end with "|".

In a script with __DATA__ :

Code

use strict; 
use warnings; 
 
while (<DATA>) { 
	if ( !/\|$/ ) { 
		chomp; 
	} 
	print; 
} 
 
__DATA__ 
Line 1 
Line 2| 
Line 3 
Line 4| 
Line 5 
Line 6|

Output:

Code

Line 1Line 2| 
Line 3Line 4| 
Line 5Line 6|

Lines 1, 3 & 5 don't end with "|", so their ending newline was removed.

(This post was edited by Kenosis on Mar 11, 2013, 3:22 PM)

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