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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
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
trace_attr_t

The following sections are informative.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2013  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013  by  the
       Institute  of  Electrical  and  Electronics  Engineers,  Inc and The Open Group.  (This is
       POSIX.1-2008 with the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/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 .