PIPE(2) UNIX Programmer's Manual PIPE(2) NAME pipe - create an interprocess communication channel SYNOPSIS pipe(fildes) int fildes[2]; DESCRIPTION The _p_i_p_e system call creates an I/O mechanism called a pipe. The file descriptors returned can be used in read and write operations. When the pipe is written using the descriptor _f_i_l_d_e_s[1] up to 4096 bytes of data are buffered before the writing process is suspended. A read using the descriptor _f_i_l_d_e_s[0] will pick up the data. It is assumed that after the pipe has been set up, two (or more) cooperating processes (created by subsequent _f_o_r_k calls) will pass data through the pipe with _r_e_a_d and _w_r_i_t_e calls. The shell has a syntax to set up a linear array of processes connected by pipes. Read calls on an empty pipe (no buffered data) with only one end (all write file descriptors closed) returns an end-of- file. Pipes are really a special case of the _s_o_c_k_e_t_p_a_i_r(2) call and, in fact, are implemented as such in the system. A signal is generated if a write on a pipe with only one end is attempted. RETURN VALUE The function value zero is returned if the pipe was created; -1 if an error occurred. ERRORS The _p_i_p_e call will fail if: [EMFILE] Too many descriptors are active. [ENFILE] The system file table is full. [EFAULT] The _f_i_l_d_e_s buffer is in an invalid area of the process's address space. SEE ALSO sh(1), read(2), write(2), fork(2), socketpair(2) BUGS Should more than 4096 bytes be necessary in any pipe among a Printed 11/26/99 August 26, 1985 1 PIPE(2) UNIX Programmer's Manual PIPE(2) loop of processes, deadlock will occur. Printed 11/26/99 August 26, 1985 2