PIPE(2) System Calls PIPE(2)
pipe - create descriptor pair for interprocess communication
int pipe (int *fildes);
The pipe function creates a pipe, which is an object allowing unidirec-
tional data flow, and allocates a pair of file descriptors. The first
descriptor connects to the read end of the pipe, and the second con-
nects to the write end, so that data written to fildes appears on
(i.e., can be read from) fildes. This allows the output of one pro-
gram to be sent to another program: The source's standard output is set
up to be the write end of the pipe, and the sink's standard input is
set up to be the read end of the pipe. The pipe itself persists until
all its associated descriptors are closed.
A pipe whose read or write end has been closed is considered widowed.
Writing on such a pipe causes the writing process to receive a SIGPIPE
signal. Widowing a pipe is the only way to deliver end-of-file to a
reader: after the reader consumes any buffered data, reading a widowed
pipe returns a zero count (end of file).
Up to 4096 bytes of data are buffered before the writing process is
suspended. Should more than 4096 bytes be necessary in any pipe among
a loop of processes, deadlock will occur. This is not a limitation
specific to GNO but to multiprogramming in general.
This man page refers to the Unix read(2) and write(2) operations. On
the IIgs, the described behavior refer to any system calls doing I/O,
GS/OS ReadGS and WriteGS
C stdio I/O routines
On successful creation of the pipe, zero is returned. Otherwise, a
value of -1 is returned and the variable errno set to indicate the
The pipe call will fail if:
EMFILE Too many descriptors are active.
ENFILE The system file table is full.
EFAULT The fildes buffer is in an invalid area of the process's
sh(1), read(2), write(2), fork(2), socketpair(2)
A pipe function call appeared in Version 6 AT&T UNIX.
GNO 16 January 1997 PIPE(2)
Man(1) output converted with