Replace date in a txt file having xml

Question

I have a text file in which i have a xml data. Now i want to replace the date from current date plus 2 days in dd/mm/yyyy format . I tried it will sed command in Unix but i am unable to do that .Below command i tried to change the date .But it is not changing the text.

sed -i 's/\<Date\>*\<Date\>/\<Date\>date +"%m/%d/%y"<Date\>/g' avltest.xml

<Args>
     <Date>01/10/2017</Date>
<\Args>

In the Date field i want to change the date whenever i run my command or i can use that command from a script.

Answer 1

Here's a perl version:

perl -MPOSIX=strftime -i -pe 's{<Date>.*?</Date>}{"<Date>" . strftime("%m/%d/%Y", localtime(time + 2 * 24 * 60 * 60)) . "</Date>"}e' avltest.xml

I removed the redundant backslashes before < and >, added the missing / in </Date>, and fixed the * part.

Answer 2

Don't use regular expressions to modify XML. It's dirty, hacky, brittle and unnecessary:

#!/usr/bin/perl
use warnings;
use strict;

use XML::Twig;
use Time::Piece;

#load your file
my $twig = XML::Twig->new->parsefile('avltest.xml');

#iterate all <Date> elements. 
foreach my $date_elt ( $twig->get_xpath('//Date') ) {
   my $date = localtime;
   #increment it by two days. 
   $date += 2 * 60 * 60 * 24; #two days. 
   #replace it. 
   $date_elt -> set_text($date -> strftime("%m/%d/%Y"));       
}

#print XML to STDOUT. 
$twig -> set_pretty_print('indented_a');
$twig -> print;

This will do what you want as described, and not be tripped up by 'end of year/end of month'.

You can use parsefile_inplace in XML twig if you prefer - that requires a slightly different code setup.