Re: open ($FH,"<named pipe") blocking

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Re^2: open ($FH,"<named pipe") blocking by Fletch (Bishop) on May 12, 2005 at 18:26 UTC
I think you misunderstood what they're asking. They're trying to open a named pipe, which is a special pipe which lives in the filesystem. When you try and open it the `open(2)` system call underneath will block if there's no writer on the other end. They need to look at the `O_NONBLOCK` flag for `sysopen` rather than using `open`. Update: Excepting of course that that will just make the `sysopen` fail with a return code of `EAGAIN` (I believe). That's just the way named pipes work; the call blocks until there's something on the other end.	[reply] [d/l] [select]
Re^3: open ($FH,"<named pipe") blocking by gnu@perl (Pilgrim) on May 12, 2005 at 18:36 UTC
You nailed it. I knew it was something simple, but it has been soooooo long since I had to use pipe for anything I forgot about sysopen. Thanks.	[reply]
Re^2: open ($FH,"<named pipe") blocking by ikegami (Patriarch) on May 12, 2005 at 18:24 UTC
No. That tells `perl`to execute the command stored in `$INFILE` and open `IN_FH` as a pipe to the command's output. That doesn't tell `perl` to open the named pipe whose name is in `$INFILE`.	[reply] [d/l] [select]
Re^2: open ($FH,"<named pipe") blocking by gnu@perl (Pilgrim) on May 12, 2005 at 18:24 UTC
That actually tells perl to exec the thing in $INFILE and read from it as if it were a pipe. like if I were to do: `$INFILE="/usr/bin/cat /var/adm/messages"; open($FH,"$INFILE\|")` [download]	[reply] [d/l]