POSIX_OPENPT(3) Linux Programmer's Manual POSIX_OPENPT(3)NAMEposix_openpt - open a pseudoterminal device
int posix_openpt(int flags);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
posix_openpt(): _XOPEN_SOURCE >= 600
The posix_openpt() function opens an unused pseudoterminal master
device, returning a file descriptor that can be used to refer to that
The flags argument is a bit mask that ORs together zero or more of the
O_RDWR Open the device for both reading and writing. It is usual to
specify this flag.
Do not make this device the controlling terminal for the
On success, posix_openpt() returns a nonnegative file descriptor which
is the lowest numbered unused descriptor. On failure, -1 is returned,
and errno is set to indicate the error.
Glibc support for posix_openpt() has been provided since version 2.2.1.
CONFORMING TOposix_openpt() is part of the UNIX 98 pseudoterminal support (see
pts(4)). This function is specified in POSIX.1-2001.
The posix_openpt() function is a recent invention in POSIX. Some UNIX
implementations that support System V (aka UNIX 98) pseudoterminals
don't have this function, but it is easy to implement:
return open("/dev/ptmx", flags);
Calling posix_openpt() creates a pathname for the corresponding pseu‐
doterminal slave device. The pathname of the slave device can be
obtained using ptsname(3). The slave device pathname exists only as
long as the master device is open.
SEE ALSOopen(2), getpt(3), grantpt(3), ptsname(3), unlockpt(3), pts(4), pty(7)COLOPHON
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