PROLOG¶

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME¶

sys/types.h — data types

SYNOPSIS¶

#include <sys/types.h>

DESCRIPTION¶

The <sys/types.h> header shall define at least the following types:

blkcnt_t

Used for file block counts.

blksize_t

Used for block sizes.

clock_t

Used for system times in clock ticks or CLOCKS_PER_SEC; see <time.h>.

clockid_t

Used for clock ID type in the clock and timer functions.

dev_t

Used for device IDs.

fsblkcnt_t

Used for file system block counts.

fsfilcnt_t

Used for file system file counts.

gid_t

Used for group IDs.

id_t

Used as a general identifier; can be used to contain at least a pid_t, uid_t, or gid_t.

ino_t

Used for file serial numbers.

key_t

Used for XSI interprocess communication.

mode_t

Used for some file attributes.

nlink_t

Used for link counts.

off_t

Used for file sizes.

pid_t

Used for process IDs and process group IDs.

pthread_attr_t

Used to identify a thread attribute object.

pthread_barrier_t

Used to identify a barrier.

pthread_barrierattr_t

Used to define a barrier attributes object.

pthread_cond_t

Used for condition variables.

pthread_condattr_t

Used to identify a condition attribute object.

pthread_key_t

Used for thread-specific data keys.

pthread_mutex_t

Used for mutexes.

pthread_mutexattr_t

Used to identify a mutex attribute object.

pthread_once_t

Used for dynamic package initialization.

pthread_rwlock_t

Used for read-write locks.

pthread_rwlockattr_t

Used for read-write lock attributes.

pthread_spinlock_t

Used to identify a spin lock.

pthread_t

Used to identify a thread.

size_t

Used for sizes of objects.

ssize_t

Used for a count of bytes or an error indication.

suseconds_t

Used for time in microseconds.

time_t

Used for time in seconds.

timer_t

Used for timer ID returned by timer_create().

trace_attr_t

Used to identify a trace stream attributes object

trace_event_id_t

Used to identify a trace event type.

trace_event_set_t

Used to identify a trace event type set.

trace_id_t

Used to identify a trace stream.

uid_t

Used for user IDs.

All of the types shall be defined as arithmetic types of an appropriate length, with the following exceptions:

pthread_attr_t
pthread_barrier_t
pthread_barrierattr_t
pthread_cond_t
pthread_condattr_t
pthread_key_t
pthread_mutex_t
pthread_mutexattr_t
pthread_once_t
pthread_rwlock_t
pthread_rwlockattr_t
pthread_spinlock_t
pthread_t
timer_t
trace_attr_t
trace_event_id_t
trace_event_set_t
trace_id_t

Additionally:

*

mode_t shall be an integer type.

*

dev_t shall be an integer type.

*

nlink_t, uid_t, gid_t, and id_t shall be integer types.

*

blkcnt_t and off_t shall be signed integer types.

*

fsblkcnt_t, fsfilcnt_t, and ino_t shall be defined as unsigned integer types.

*

size_t shall be an unsigned integer type.

*

blksize_t, pid_t, and ssize_t shall be signed integer types.

*

clock_t shall be an integer or real-floating type. time_t shall be an integer type.

The type ssize_t shall be capable of storing values at least in the range [-1, {SSIZE_MAX}].

The type suseconds_t shall be a signed integer type capable of storing values at least in the range [-1, 1000000].

The implementation shall support one or more programming environments in which the widths of blksize_t, pid_t, size_t, ssize_t, and suseconds_t are no greater than the width of type long. The names of these programming environments can be obtained using the confstr() function or the getconf utility.

There are no defined comparison or assignment operators for the following types:

pthread_attr_t
pthread_barrier_t
pthread_barrierattr_t
pthread_cond_t
pthread_condattr_t
pthread_mutex_t
pthread_mutexattr_t
pthread_rwlock_t
pthread_rwlockattr_t
pthread_spinlock_t
timer_t
trace_attr_t

The following sections are informative.

APPLICATION USAGE¶

None.

RATIONALE¶

None.

FUTURE DIRECTIONS¶

None.

SEE ALSO¶

<time.h>

The System Interfaces volume of POSIX.1‐2017, confstr()

The Shell and Utilities volume of POSIX.1‐2017, getconf

COPYRIGHT¶

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .