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       rexec, rexec_af - return stream to a remote command


       #define _BSD_SOURCE             /* See feature_test_macros(7) */
       #include <netdb.h>

       int rexec(char **ahost, int inport, const char *user,
                 const char *passwd, const char *cmd, int *fd2p);

       int rexec_af(char **ahost, int inport, const char *user,
                    const char *passwd, const char *cmd, int *fd2p,
                    sa_family_t af);


       This interface is obsoleted by rcmd(3).

       The  rexec() function looks up the host *ahost using gethostbyname(3), returning -1 if the
       host does not exist.  Otherwise, *ahost is set to the standard name of  the  host.   If  a
       username  and  password  are  both  specified,  then these are used to authenticate to the
       foreign host; otherwise the environment and then the .netrc file in user's home  directory
       are searched for appropriate information.  If all this fails, the user is prompted for the

       The port inport specifies which well-known DARPA Internet port to use for the  connection;
       the  call  getservbyname("exec",  "tcp")  (see  getservent(3))  will return a pointer to a
       structure that contains the necessary port.  The protocol for connection is  described  in
       detail in rexecd(8).

       If  the  connection  succeeds,  a  socket  in  the  Internet domain of type SOCK_STREAM is
       returned to the caller, and given to the remote command as stdin and stdout.  If  fd2p  is
       nonzero,  then  an  auxiliary channel to a control process will be setup, and a descriptor
       for it will be placed in *fd2p.  The control process will return  diagnostic  output  from
       the  command (unit 2) on this channel, and will also accept bytes on this channel as being
       UNIX signal numbers, to be forwarded to the process group of the command.  The  diagnostic
       information  returned  does  not  include  remote  authorization failure, as the secondary
       connection is set up after authorization has been verified.  If fd2p is 0, then the stderr
       (unit  2  of  the  remote command) will be made the same as the stdout and no provision is
       made for sending arbitrary signals to the remote process, although you may be able to  get
       its attention by using out-of-band data.

       The  rexec()  function  works  over  IPv4 (AF_INET).  By contrast, the rexec_af() function
       provides an extra argument, af, that allows the  caller  to  select  the  protocol.   This
       argument  can be specified as AF_INET, AF_INET6, or AF_UNSPEC (to allow the implementation
       to select the protocol).


       The rexec_af() function was added to glibc in version 2.2.


       For an explanation of the terms used in this section, see attributes(7).

       │InterfaceAttributeValue     │
       │rexec(), rexec_af() │ Thread safety │ MT-Unsafe │


       These functions are not in POSIX.1.  The rexec() function first appeared in 4.2BSD, and is
       present  on  the  BSDs,  Solaris, and many other systems.  The rexec_af() function is more
       recent, and less widespread.


       The rexec() function sends the unencrypted password across the network.

       The underlying service is considered a big security hole and therefore not enabled on many
       sites; see rexecd(8) for explanations.


       rcmd(3), rexecd(8)


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