#define _GNU_SOURCE             /* See feature_test_macros(7) */
       #include <sched.h>

       int setns(int fd, int nstype);

       Given a file descriptor referring to a namespace, reassociate the call-
       ing thread with that namespace.

       The fd argument is a file descriptor referring to one of the  namespace
       entries  in a /proc/[pid]/ns/ directory; see proc(5) for further infor-
       mation on /proc/[pid]/ns/.  The calling  thread  will  be  reassociated
       with the corresponding namespace, subject to any constraints imposed by
       the nstype argument.

       The nstype argument specifies  which  type  of  namespace  the  calling
       thread  may  be  reassociated  with.  This argument can have one of the
       following values:

       0      Allow any type of namespace to be joined.

              fd must refer to an IPC namespace.

              fd must refer to a network namespace.

              fd must refer to a UTS namespace.

       Specifying nstype as 0 suffices if the caller knows (or does not  care)
       what  type  of  namespace  is  referred to by fd.  Specifying a nonzero
       value for nstype is useful if the caller does not  know  what  type  of
       namespace  is  referred to by fd and wants to ensure that the namespace
       is of a particular type.  (The caller might not know the  type  of  the
       namespace  referred  to  by  fd  if  the  file descriptor was opened by
       another process and, for example, passed  to  the  caller  via  a  UNIX
       domain socket.)

       On success, setns() returns 0.  On failure, -1 is returned and errno is
       set to indicate the error.

       EBADF  fd is not a valid file descriptor.

       EINVAL fd refers to a namespace whose type does not match  that  speci-
              fied  in  nstype, or there is problem with reassociating the the
              thread with the specified namespace.

       ENOMEM Cannot allocate sufficient memory to change the specified names-

       ated using clone(2) can be changed using setns().

       The  PID namespace and the mount namespace are not currently supported.
       (See the descriptions of CLONE_NEWPID and CLONE_NEWNS in clone(2).)

       clone(2), fork(2), vfork(2), proc(5), unix(7)

       This page is part of release 3.35 of the Linux  man-pages  project.   A
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       be found at

Linux                             2011-10-04                          SETNS(2)
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