REXEC(3)                   Linux Programmer's Manual                  REXEC(3)

       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 information.

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

       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 std-
       out 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

       |Interface           | Attribute     | Value     |
       |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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       description  of  the project, information about reporting bugs, and the
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Linux                             2015-03-02                          REXEC(3)
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