1POSIX_OPENPT(3) Linux Programmer's Manual POSIX_OPENPT(3)
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6 posix_openpt - open a pseudoterminal device
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9 #include <stdlib.h>
10 #include <fcntl.h>
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12 int posix_openpt(int flags);
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14 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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16 posix_openpt():
17 _XOPEN_SOURCE >= 600
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20 The posix_openpt() function opens an unused pseudoterminal master de‐
21 vice, returning a file descriptor that can be used to refer to that de‐
22 vice.
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24 The flags argument is a bit mask that ORs together zero or more of the
25 following flags:
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27 O_RDWR Open the device for both reading and writing. It is usual to
28 specify this flag.
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30 O_NOCTTY
31 Do not make this device the controlling terminal for the
32 process.
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35 On success, posix_openpt() returns a file descriptor (a nonnegative in‐
36 teger) which is the lowest numbered unused file descriptor. On fail‐
37 ure, -1 is returned, and errno is set to indicate the error.
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40 See open(2).
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43 Glibc support for posix_openpt() has been provided since version 2.2.1.
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46 For an explanation of the terms used in this section, see at‐
47 tributes(7).
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49 ┌────────────────────────────────────────────┬───────────────┬─────────┐
50 │Interface │ Attribute │ Value │
51 ├────────────────────────────────────────────┼───────────────┼─────────┤
52 │posix_openpt() │ Thread safety │ MT-Safe │
53 └────────────────────────────────────────────┴───────────────┴─────────┘
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56 POSIX.1-2001, POSIX.1-2008.
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58 posix_openpt() is part of the UNIX 98 pseudoterminal support (see
59 pts(4)).
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62 Some older UNIX implementations that support System V (aka UNIX 98)
63 pseudoterminals don't have this function, but it can be easily imple‐
64 mented by opening the pseudoterminal multiplexor device:
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66 int
67 posix_openpt(int flags)
68 {
69 return open("/dev/ptmx", flags);
70 }
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72 Calling posix_openpt() creates a pathname for the corresponding pseu‐
73 doterminal slave device. The pathname of the slave device can be ob‐
74 tained using ptsname(3). The slave device pathname exists only as long
75 as the master device is open.
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78 open(2), getpt(3), grantpt(3), ptsname(3), unlockpt(3), pts(4), pty(7)
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81 This page is part of release 5.13 of the Linux man-pages project. A
82 description of the project, information about reporting bugs, and the
83 latest version of this page, can be found at
84 https://www.kernel.org/doc/man-pages/.
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88 2021-03-22 POSIX_OPENPT(3)