#TopAndTail.pl 
#Removes header and footer lines from text files. 
#John Nurick 2004-05

use strict;
die "\nTopAndTail.pl: removes header and footer lines from text files. \n\n" .
  "Usage: perl TopAndTail.pl  filespec  hdrlines  ftrlines  [-b]\n\n" .
  "    filespec can be a wildcard \n" .
  "    hdrlines and ftrlines are number of lines to omit.\n" .
  "    -b is optional switch to leave original file with .BAK extension.\n\n" .
  "NB: slurps each file into memory so not suitable for very large files." 
  unless defined $ARGV[2];

my ($hdrlines, $ftrlines) = @ARGV[1 .. 2];
my $iofile; #path and name of input file
my $bakname; #path and name for backup file

undef $/; #slurp entire file

my @files = glob($ARGV[0]);   #treat first argument as a wildcard

foreach $iofile (@files) {   
  open IOFILE, $iofile or die "Couldn't open $iofile for input.\n"; 
  my (@lines) = split "\n", <IOFILE>;
  if ($#lines < $hdrlines + $ftrlines) {
    warn "$iofile doesn't have enough lines!\n";
    close IOFILE;
    next;
  }
  close IOFILE;
  if ($ARGV[3] =~ m(^-b)i ) {  # -b switch
    $bakname = $iofile;
    $bakname =~ s/\.[^\.]*$/\.BAK/;
    unlink $bakname;   #delete old .BAK file if it exists
    rename $iofile, $bakname;
  }
  pop @lines until $lines[-1]; #dump any empty line(s) due to \n at end of infile
  open IOFILE, "> $iofile" or die "Couldn't open $iofile for output.\n";
  print IOFILE join "\n", @lines[$hdrlines .. $#lines - $ftrlines];
  close IOFILE;
  print STDOUT "$iofile\n";  #list files as they are processed
}