in reply to Re^2: Buffered, bruised and broken
in thread Buffered, bruised and broken
But that solution, in itself, raises another question. Why should setting $| fix the problem ?
Output buffers are not provided by the OS. Each library that does output buffering provides its own system. When you are using the C lib to do output, you use its buffers. PerlIO apparently does not use the C lib for output and thus has independent buffers.
The real solution is to use the functions documented in perlapio instead of the C output functions. ( Oops, you already said that )
Setting $| should flush only the perl buffer, shouldn't it ? And that buffer was already being flushed by the trailing "\n"
"\n" only flushes STDOUT when it's connected to a terminal. By redirecting the output, you turn on full buffering. $|=1; turns it off, returning to a situation similar to when you didn't redirect STDOUT (but different since it's not even line buffered now).
| STDOUT->autoflush(0) | STDOUT is connected to a terminal | STDOUT is line buffered (flushed by "\n") |
| STDOUT->autoflush(0) | STDOUT isn't connected to a terminal | STDOUT is block buffered (not flushed by "\n") |
| STDOUT->autoflush(1) | STDOUT isn't buffered (flushed after every print) | |
| STDERR->autoflush(0) | STDERR isn't buffered (flushed after every print) | |
| STDERR->autoflush(1) | STDERR isn't buffered (flushed after every print) | |
| $fh->autoflush(0) | $fh is block buffered (not flushed by "\n") | |
| $fh->autoflush(1) | $fh isn't buffered (flushed after every print) | |
(Where $fh is any handle other than STDOUT and STDERR)
Update: Apparently, one cannot turn off autoflush on STDERR, so I updated the table.
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