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PIPE(2) BSD System Calls Manual PIPE(2) NAME pipe -- create descriptor pair for interprocess communication SYNOPSIS #include <unistd.h> int pipe(int fildes[2]); DESCRIPTION The pipe() function creates a pipe (an object that allows unidirectional data flow) and allocates a pair of file descriptors. The first descrip-tor descriptor tor connects to the read end of the pipe; the second connects to the write end. Data written to fildes[1] appears on (i.e., can be read from) fildes[0]. This allows the output of one program to be sent to another program: the source's standard output is set up to be the write end of the pipe; the sink's standard input is set up to be the read end of the pipe. The pipe itself persists until all of 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. RETURN VALUES On successful creation of the pipe, zero is returned. Otherwise, a value of -1 is returned and the variable errno set to indicate the error. ERRORS The pipe() call will fail if: [EFAULT] The fildes buffer is in an invalid area of the process's address space. [EMFILE] Too many descriptors are active. [ENFILE] The system file table is full. SEE ALSO sh(1), fork(2), read(2), socketpair(2), write(2) HISTORY A pipe() function call appeared in Version 6 AT&T UNIX. 4th Berkeley Distribution June 4, 1993 4th Berkeley Distribution |