I have a tiny script that reads a list of file names on stdin, and outputs the same entries prefixed with modification date, in order of oldest to newest. I have used the script extensively for several years.

Today I noticed that two of the three last lines of output are identical. I wonder if my cygwin setup has been corrupted, or if the latest update has a bug. Can you spot a mistake on my part?

The code creates a hash with file names as keys and timestamps as values. Then it iterates over the keys of the hash, like this:

# read the paths and stat each one
while (defined ($_=<>)) {
  my $f;
  my @s;
  ( $f = $_ ) =~ s/\r?\n$//;
  next unless @s = stat($f);
  $t{$f}=$s[9];
}

# Sort and write to stdout
for $_ (sort {$t{$a} <=> $t{$b}} keys %t) {
  my $f = $_;
  my $d = POSIX::strftime("%F %T", localtime $t{$_});
  if ($dospath) {
        $f = Filesys::CygwinPaths::win32path($f);
  }
  print $d, " ", $f, "\n";
}

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(File names are optionally converted to "windows" format "c:\xxx\yyy.zzz" instead of "/cygdrive/c/xxx/yyy.zzz". Timestamps are integers, seconds since end year 1969.)

Even in the case of repeated file names in the input, the output should not have repetitions. (Provided the spelling is the same. I used copy-n-paste from the output into a bash statement [ '' = '' ] && echo equal || echo different in order to make sure I was not overlooking a tiny difference.)

Here are two examples of the output, on the same input data. Notice that the order differs, but there are two files with the exact same Unix timestamp. In every case so far it has been the shorter name that appears repeated. I have not observed any repetitions among files with earlier dates

$ locate zeraia | sort-files-by-date | tail
2017-07-03 14:15:32 C:\Users\Heidi\Dropbox\Teknisk\gpg-db\zeraia-17-07
+-03-14-15.gpg
2017-07-03 16:42:59 C:\Users\Heidi\Dropbox\Teknisk\gpg-db\zeraia-17-07
+-03-16-42.gpg
2017-07-03 16:42:59 C:\cygwin\var\gpg-db\zeraia-17-07-03-16-42.gpg
2017-07-03 21:30:10 C:\Users\Heidi\Dropbox\Teknisk\gpg-db\zeraia-17-07
+-03-21-30.gpg
2017-07-03 21:30:10 C:\cygwin\var\gpg-db\zeraia-17-07-03-21-30.gpg
2017-07-14 18:38:14 C:\cygwin\var\gpg-db\zeraia-17-07-14-18-38.gpg
2017-07-14 18:38:14 C:\Users\Heidi\Dropbox\Teknisk\gpg-db\zeraia-17-07
+-14-18-38.gpg
2017-07-24 14:02:59 C:\cygwin\var\gpg-db\zeraia-17-07-24-14-02.gpg
2017-07-24 14:02:59 C:\cygwin\var\gpg-db\zeraia-17-07-24-14-02.gpg
2017-07-24 14:02:59 C:\Users\Heidi\Dropbox\Teknisk\gpg-db\zeraia-17-07
+-24-14-02.gpg

$ locate zeraia | sort-files-by-date | tail
2017-07-03 14:15:32 C:\Users\Heidi\Dropbox\Teknisk\gpg-db\zeraia-17-07
+-03-14-15.gpg
2017-07-03 16:42:59 C:\cygwin\var\gpg-db\zeraia-17-07-03-16-42.gpg
2017-07-03 16:42:59 C:\Users\Heidi\Dropbox\Teknisk\gpg-db\zeraia-17-07
+-03-16-42.gpg
2017-07-03 21:30:10 C:\cygwin\var\gpg-db\zeraia-17-07-03-21-30.gpg
2017-07-03 21:30:10 C:\Users\Heidi\Dropbox\Teknisk\gpg-db\zeraia-17-07
+-03-21-30.gpg
2017-07-14 18:38:14 C:\Users\Heidi\Dropbox\Teknisk\gpg-db\zeraia-17-07
+-14-18-38.gpg
2017-07-14 18:38:14 C:\cygwin\var\gpg-db\zeraia-17-07-14-18-38.gpg
2017-07-24 14:02:59 C:\Users\Heidi\Dropbox\Teknisk\gpg-db\zeraia-17-07
+-24-14-02.gpg
2017-07-24 14:02:59 C:\cygwin\var\gpg-db\zeraia-17-07-24-14-02.gpg
2017-07-24 14:02:59 C:\cygwin\var\gpg-db\zeraia-17-07-24-14-02.gpg

[download]

In reply to iterating hash keys sorted by values - last key twice? by Cacadril

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