Presumably you call this script like this:

$ fix.pl wrong.data fixed.data

Here is a blow by blow:

# command line arguments are available to the script in the 
# @ARGV array. Thus the first argument is in $ARGV[0], the 
# second in $ARGV[1]....

# Open the file specified in the first command line arg for reading
open(IN, "$ARGV[0]") || die "unable to open $ARGV[0]"; 

# Open the file specified in the second command line arg for writing
open(OUT, ">$ARGV[1]") || die "unable to open $ARGV[0]"; 

# stop perl making automatic \r\n => \n or \r => \n line ending 
# conversions which are required on Win32 and Mac respectively
binmode(OUT);        #set output mode as binary

# now iterate over our input file on line at a time
while(<IN>)  {

    # if we have a line that contains only "\n" - ie a blank line 
    if(/^\n$/) { 

        # then we print "\r\n" instead of the existing "\n" into our o
+utput file
        print OUT "\r\n"; 
    } 

    # otherwise just print out the totally unaltered line
    else { print OUT; }    # else just print line with a CR
}

# close the input and output files
close(IN); close(OUT);
[download]

If you want a short way to do the same this will do it with an inplace edit. You call it like this fix.pl data The data in data will get munged and a backup will be made called data.bak The backup will contain the original data, the argument file the modified data.

#!/usr/bin/perl -i.bak -w
while (<>) {
    s/^\n$/\r\n/;
    print;
}
[download]

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

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