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).

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.1‐2008, <dlfcn.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2013  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013  by  the
       Institute  of  Electrical  and  Electronics  Engineers,  Inc and The Open Group.  (This is
       POSIX.1-2008 with the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/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 .