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 .