my $file = $ARGV[0];
my $repl = $ARGV[1];

open INFO, "<", $file or die $!;

while (<INFO>)
{
    s/(Absolute_Error_Tolerance=&Quot;)1e-15(&Quot)/$1$repl$2/;
    print;
}

close INFO;

##</code><code>##

perl -n -e "s/(Absolute_Error_Tolerance=&Quot;)1e-15(&Quot)/$1$ARGV[0]$2/;
    print;" filename

##</code><code>##

@echo off
perl -n -e "s/(Absolute_Error_Tolerance=&Quot;)1e-15(&Quot)/$1%2$2/; print;" %1 

##</code><code>##

batchfilename datafile replacement