/usr/lib/cd-hit/clstr_rev.pl is in cd-hit 4.6.8-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82  | #!/usr/bin/perl
# if nr90 from nr100 and
#    nr80 from nr90, so I have nr90.clstr and nr80.clstr
# but, in nr80.clstr, some gi numbers whose from nr100 are there
# use this script, I create a new nr80new.clstr, as it is clustered from nr100
$file90 = shift;
$file80 = shift;
my %gi2clstr = ();
open(TMP, $file90) || die "Can not open file";
$readin = 0;
my $gi = "";
my $clstr = "";
my $this_no = 0;
while(my $ll=<TMP>) {
  if ($ll =~ /^>/ ) {
    if ($readin and $gi and $this_no>1 ) {
      $gi2clstr{$gi} = $clstr;
    }
    $gi="";
    $clstr="";
    $this_no=0;
  }
  else {
    $readin = 1;
    $clstr .= $ll;
    if ($ll =~ /\*/ and $ll =~ />(.+)\.\.\./ ) { $gi = $1; }
    $this_no++;
  }
}
close(TMP);
if ($readin and $gi and $this_no>1 ) {
  $gi2clstr{$gi} = $clstr;
}
my $no = 0;
open(TMP, $file80) || die "Can not open file";
while( $ll = <TMP>) {
  if ($ll =~ /^>/ ) {
    print $ll;
    $no = 0;
  }
  elsif ($ll =~ />(.+)\.\.\./ ) {
    $gi = $1; 
    chop($ll);
    $rep = ( $ll =~ /\*$/) ? 1 : 0;
    $iden = "";
    if ($ll =~ / at (.+)$/) { $iden = $1; }
    else                  { $iden = "100%"; }
    if ( $gi2clstr{$gi} ) {
      $aa = $gi2clstr{$gi};
      @aa = split(/\n/, $aa);
      foreach $a (@aa) {
        $a =~ s/^\d+/$no/;
        if (not $rep) {
          if ($a =~ /\*$/) {
            $a =~ s/\*/at $iden/;
          }
          else {
            $a =~ s/at (.+)$/at $iden,$1/;
          }
        }
        print "$a\n";
        $no++;
      }
    }
    else { 
     $ll =~ s/^\d+/$no/;
     print "$ll\n";
     $no++;
    }
  }
  else {
    print $ll;
  }
}
close(TMP);
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