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openpty(3) Library Functions Manual openpty(3) NAME openpty, forkpty - Open and fork pseudoterminals LIBRARY Standard C Library (libc.a) SYNOPSIS #include <sys/termios.h> <sys/ioctl.h> int openpty( int *master, int *slave, char *name, struct termios *termp, struct winsize *winp); pid_t forkpty( int *master, char *name, struct termios *termp, struct winsize *winp); PARAMETERS Points to the returned file descriptor for the master pseudoterminal (pty). Points to the returned file descriptor for the slave pty. Points to the pathname of the slave pty. This parameter is optional. Specifies the termios structure containing the terminal attributes for the opened slave pty. This parameter is optional. Specifies the win- size structure containing the window attributes for the opened slave pty. This parameter is optional. DESCRIPTION The openpty() function opens the pty master/slave pair and sets the terminal attributes of the slave pseudoterminal according to the speci- fications in the termp and winp parameters. The forkpty() function creates a child process and establishes the slave pty as the child process' controlling terminal. Note If a signal handler for SIGCHLD exists and the openpty() or forkpty() function is invoked without superuser privileges, the signal handler must be able to dismiss an unexpected SIGCHLD sig- nal. RETURN VALUES Upon successful completion, the openpty() function returns a value of 0 (zero). Otherwise, it returns a value of -1. On success, the forkpty() function returns a value of 0 (zero) to the child process and returns the process ID of the child process to the parent process. On error, the forkpty() function returns a value of -1 to the parent process and does not create a child process. ERRORS If any of the following conditions occurs, the openpty() function sets errno to the corresponding value: The slave pty special files have been exhausted. No more ptys can be opened. The configured number of ptys has been reached. The system limit for open file descriptors per process has already reached OPEN_MAX. The system limit for open file descriptors has been reached. [DIGITAL] Either the OPEN_MAX value or the per-process soft de- scriptor limit is checked. The system file table is full. The system was unable to allocate kernel memory for more file de- scriptors/processes. The system-imposed limit on the total num- ber of processes executing for a single user has been exceeded. This limit can be exceeded by a process with superuser privi- lege. RELATED INFORMATION Functions: fork(2) delim off openpty(3)