This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       Applications must provide the space in s1 for the n bytes to be transferred, as well as ensure  that  the
       s2 and s1 arrays do not overlap.

       Character  movement  is  performed  differently in different implementations. Thus, overlapping moves may
       yield surprises.

       If there is no NUL character byte in the first n bytes of the array pointed to by s2, the result  is  not
       null-terminated.

       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 .

IEEE/The Open Group                                   2017                                       STRNCPY(3POSIX)

       For strncpy(): The functionality described on this reference page is aligned with the ISO C standard. Any
       conflict  between the requirements described here and the ISO C standard is unintentional. This volume of
       POSIX.1‐2017 defers to the ISO C standard.

       The stpncpy() and strncpy() functions shall copy not more than n bytes (bytes that follow a NUL character
       are not copied) from the array pointed to by s2 to the array pointed to by s1.

       If the array pointed to by s2 is a string that is shorter than n bytes, NUL characters shall be  appended
       to the copy in the array pointed to by s1, until n bytes in all are written.

       If copying takes place between objects that overlap, the behavior is undefined.

       No errors are defined.

       Thefollowingsectionsareinformative.

       None.

       None.

       stpncpy, strncpy — copy fixed length string, returning a pointer to the array end

       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.

       None.

       If  a NUL character is written to the destination, the stpncpy() function shall return the address of the
       first such NUL character.  Otherwise, it shall return &s1[n].

       The strncpy() function shall return s1.

       No return values are reserved to indicate an error.

strcpy(), wcsncpy()

       The Base Definitions volume of POSIX.1‐2017, <string.h>

       #include <string.h>

       char *stpncpy(char *restrict s1, const char *restrict s2, size_t n);
       char *strncpy(char *restrict s1, const char *restrict s2, size_t n);