ruler

#!/usr/bin/perl

$columns = $ARGV[0];
# || $ENV{'COLUMNS'};
if ( $columns < 1 ) {
   @rc = split(/ /, `stty size`);
   $columns = $rc[1] + 0;
}

# print "0: $ARGV[0], 1: $ARGV[1]  stty: " . $columns . "\n";

# $zero_based = 1;
# emacs ^X = (what-cursor-position) is zero-based
# NOTE:  this does not match the number that 'cut' expects, which is +1 

# no arg processing yet.
$zero_based = 0;

if ( $zero_based ) {
  # zero (_) through 9
  $z9 = join('', '_', 1..9 );
} else {
  # 9 through zero
  $z9 = join('',  1..9, '_', );
}

$tens = int( $columns/10 );

# 0..9
for ( 1.. $tens   ) { print $z9; }
print substr( $z9,              0, $columns - 10*$tens), "\n";

# 'tens' line
for ( 0.. $tens-1 ) {
  if ( $zero_based ) {
    $tensline =  "${_}_________";
  print substr( $tensline,0,10 );
  } else {    
    $tensline = sprintf("__________%d", 1+$_);
    #print "$tensline\n";
    print substr( $tensline,length("$_"),10 );
  }
}

if ( $zero_based ) {
  print substr( "$tens         ", 0, $columns - 10*$tens ), "\n";
} else {
    $tensline = sprintf("__________%d", $tens);
    print substr( $tensline,length("$tens"), $columns - 10*$tens );
    print "\n";
}