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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
       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 .