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

       rexec, rexec_af - return stream to a remote command

       #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);

       rexec(), rexec_af():
           Since glibc 2.19:
           In glibc up to and including 2.19:

       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 di-
       rectory 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 file 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  at-

       |Interface           | Attribute     | Value     |
       |rexec(), rexec_af() | Thread safety | MT-Unsafe |
       These  functions  are  not  in POSIX.1.  The rexec() function first ap-
       peared 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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Linux                             2017-09-15                          REXEC(3)
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