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

       dlerror — get diagnostic information

SYNOPSIS

       #include <dlfcn.h>

       char *dlerror(void);

DESCRIPTION

       The  dlerror() function shall return a null-terminated character string (with no trailing <newline>) that
       describes the last error that occurred during dynamic linking processing. If no  dynamic  linking  errors
       have  occurred  since  the  last  invocation  of  dlerror(), dlerror() shall return NULL.  Thus, invoking
       dlerror() a second time, immediately following a prior invocation, shall result in NULL being returned.

       It is implementation-defined whether  or  not  the  dlerror()  function  is  thread-safe.  A  thread-safe
       implementation shall return only errors that occur on the current thread.

RETURN VALUE

       If  successful,  dlerror()  shall  return  a  null-terminated  character string; otherwise, NULL shall be
       returned.

       The application shall not modify the string returned. The returned pointer might be  invalidated  or  the
       string content might be overwritten by a subsequent call to dlerror() in the same thread (if dlerror() is
       thread-safe) or in any thread (if dlerror() is not thread-safe).  The  returned  pointer  might  also  be
       invalidated if the calling thread is terminated.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       The following example prints out the last dynamic linking error:

           ...
           #include <dlfcn.h>

           char *errstr;

           errstr = dlerror();
           if (errstr != NULL)
               printf ("A dynamic linking error occurred: (%s)\n", errstr);
           ...

APPLICATION USAGE

       Depending  on  the application environment with respect to asynchronous execution events, such as signals
       or other asynchronous computation sharing  the  address  space,  conforming  applications  should  use  a
       critical section to retrieve the error pointer and buffer.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       dlclose(), dlopen(), dlsym()

       The Base Definitions volume of POSIX.1‐2017, <dlfcn.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 .