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

       strdup, strndup — duplicate a specific number of bytes from a string

SYNOPSIS

       #include <string.h>

       char *strdup(const char *s);
       char *strndup(const char *s, size_t size);

DESCRIPTION

       The  strdup() function shall return a pointer to a new string, which is a duplicate of the
       string pointed to by s.  The returned pointer can be passed to free().  A null pointer  is
       returned if the new string cannot be created.

       The  strndup()  function  shall  be  equivalent  to the strdup() function, duplicating the
       provided s in a new block of memory allocated as if by using malloc(), with the  exception
       being  that  strndup() copies at most size plus one bytes into the newly allocated memory,
       terminating the new string with a NUL character. If the length of s is larger  than  size,
       only  size bytes shall be duplicated. If size is larger than the length of s, all bytes in
       s shall be copied into the new memory buffer, including the terminating NUL character. The
       newly created string shall always be properly terminated.

RETURN VALUE

       The  strdup()  function  shall  return a pointer to a new string on success. Otherwise, it
       shall return a null pointer and set errno to indicate the error.

       Upon successful completion, the strndup() function shall return a  pointer  to  the  newly
       allocated  memory  containing  the  duplicated  string.  Otherwise, it shall return a null
       pointer and set errno to indicate the error.

ERRORS

       These functions shall fail if:

       ENOMEM Storage space available is insufficient.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       For functions that allocate memory as if by malloc(), the application should release  such
       memory  when  it  is  no longer required by a call to free().  For strdup() and strndup(),
       this is the return value.

       Implementations are free to malloc() a buffer  containing  either  (size  +  1)  bytes  or
       (strnlen( s, size) + 1) bytes. Applications should not assume that strndup() will allocate
       (size + 1) bytes when strlen( s) is smaller than size.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       free(), wcsdup()

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

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 .