1 files changed, 43 insertions, 0 deletions
diff --git a/extools/merge_lines.pl b/extools/merge_lines.pl
new file mode 100755
index 00000000..8711e4ce
--- /dev/null
+++ b/extools/merge_lines.pl
@@ -0,0 +1,43 @@
+#!/usr/bin/perl -w
+use strict;
+
+if (scalar @ARGV < 2) {
+  die "Usage: $0 file1.txt file2.txt ...\n\n  Concatenate the nth line of each input file. All files\n  must be the same length.\n\n";
+}
+
+my @fhs=();
+for my $file (@ARGV) {
+  my $fh;
+  open $fh, "<$file" or die "Can't read $file: $!\n";
+  push @fhs, $fh;
+}
+
+my $first = shift @fhs;
+
+while(my $x = <$first>) {
+  my $ind = 0;
+  chomp $x;
+  my @fields = ($x);
+  for my $fh (@fhs) {
+    $ind++;
+    $x = <$fh>;
+    die "ERROR: Mismatched number of lines: $ARGV[$ind]\n" unless $x;
+    chomp $x;
+    push @fields, $x;
+  }
+  print join ' ||| ', @fields;
+  print "\n";
+}
+my $ind = 0;
+for my $fh (@fhs) {
+  $ind++;
+  my $x=<$fh>;
+  die "ERROR: $ARGV[$ind] has extra lines!\n" if $x;
+}
+
+exit 0;
+
+for my $fh (@fhs) {
+  close $fh;
+}
+