#! perl

# Store on screen help text in a variable
$syntax = "\nDblCr2Cr.pl, Version 1.00\n";
$syntax = $syntax."Replace double CR/LF pairs (0D0Ax) by single pairs\n\n";
$syntax = $syntax."Usage:  DBLCR2CR.PL [ infile [ outfile ] ]\n";
$syntax = $syntax."or:     any_command | PERL.EXE DBLCR2CR.PL > outfile\n";
$syntax = $syntax."or:     DBLCR2CR.PL /?\n\n";
$syntax = $syntax."Where:  \"any_command\"  is a command that's standard output is used\n";
$syntax = $syntax."                       instead of \"infile\"\n";
$syntax = $syntax."        \"infile\"       is an ASCII file with double line terminations\n";
$syntax = $syntax."                       (default: standard input)\n";
$syntax = $syntax."        \"outfile\"      is the corrected ASCII file\n";
$syntax = $syntax."                       (default: standard output)\n\n";
$syntax = $syntax."Written by Rob van der Woude\n";
$syntax = $syntax."http://www.robvanderwoude.com\n";

# Help required?
if ( @ARGV[0] eq "/?" ) {
	die $syntax;
}

# Use source file as standard input if specified
if ( @ARGV[0] ) {
	open( STDIN, "< @ARGV[0]" ) || die "Cannot open file @ARGV[0]:\n$!\n\n$syntax";
}

# Use target file as standard output if specified
if ( @ARGV[1] ) {
	open( STDOUT, "> @ARGV[1]" ) || die "Cannot open file @ARGV[1]:\n$!\n\n$syntax";
}

# Switch to slurp mode
undef $/;

# Search and replace standard input and write to standard output
while ( <STDIN> ) {
	$line = $_;
	$line =~ s/\n\n/\n/g;
	print $line;
}

# Close "file" handles
close( STDIN  );
close( STDOUT );