dlerror - Man Page

get diagnostic information


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.


#include <dlfcn.h>

char *dlerror(void);


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.


No errors are defined.

The following sections are informative.


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.



Future Directions


See Also

dlclose(), dlopen(), dlsym()

The Base Definitions volume of POSIX.1-2017, <dlfcn.h>

Referenced By

dlclose(3p), dlfcn.h(0p), dlopen(3p), dlsym(3p).

2017 IEEE/The Open Group POSIX Programmer's Manual