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28 .\" @(#)pipe.2 8.1 (Berkeley) 6/4/93
36 .Nd create descriptor pair for interprocess communication
42 .Fn pipe "int fildes[2]"
49 which is an object allowing
50 bidirectional data flow,
51 and allocates a pair of file descriptors.
53 By convention, the first descriptor is normally used as the
56 and the second is normally the
58 so that data written to
60 appears on (i.e., can be read from)
62 This allows the output of one program to be
65 the source's standard output is set up to be
66 the write end of the pipe,
67 and the sink's standard input is set up to be
68 the read end of the pipe.
69 The pipe itself persists until all its associated descriptors are
72 A pipe that has had an end closed is considered
74 Writing on such a pipe causes the writing process to receive
78 Widowing a pipe is the only way to deliver end-of-file to a reader:
79 after the reader consumes any buffered data, reading a widowed pipe
82 The bidirectional nature of this implementation of pipes is not
83 portable to older systems, so it is recommended to use the convention
84 for using the endpoints in the traditional manner when using a
85 pipe in one direction.
91 system call will fail if:
94 Too many descriptors are active.
96 The system file table is full.
98 Not enough kernel memory to establish a pipe.
112 Bidirectional pipes were first used on