in reply to Is it possible to use the open( ) function with piped unix commands?

It works just fine from perl. Your problem probably is that uniq only works on sorted lists, i.e. you want 
open(LIST, "| sort -n| uniq");

[download]
and also, you need to explicitly close the LIST handle to make sort the whole pipe stop (update: i don't really know why you need to, but this code doesn't work without the close() statement ): 
perl -e'open F,"|sort|uniq"; print F "aa\n","bb\n","aa\n","bb\n"; clos
+e F'

[download]
output: 
aa
bb

[download]
"What should it profit a man, if he should win a flame war, yet lose his cool?"

Replies are listed 'Best First'.
Re^2: Is it possible to use the open( ) function with piped unix commands?
by runrig (Abbot) on Jul 19, 2007 at 00:01 UTC
    And most sort's have a "-u" option so you don't need to use "uniq".
[reply]
Re^2: Is it possible to use the open( ) function with piped unix commands?
by ikegami (Patriarch) on Jul 19, 2007 at 14:44 UTC

    On perl's side, closing the file handle flushes the data and releases the process (does a waitpid).

    On sort's side, the closed input tells sort it's done receiving data so it can proceed to sort and print it.

[reply]
[d/l]
[select]
      Yes, but I assumed that perl would close F at end of script, flushing the buffers. Instead, without the close() statement, the program just waits.

      After some more testing, it appears that I got confused. Perl does close the pipe when you don't do it yourself, but the output is printed just after the new prompt. (which is why i got confused)

      "What should it profit a man, if he should win a flame war, yet lose his cool?"
[reply]

        Thanks to all for the great feedback.
        It was really appreciated.

[reply]

In Section Seekers of Perl Wisdom