NAME

       rexec, rexec_af - return stream to a remote command

SYNOPSIS

       #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:
               _DEFAULT_SOURCE
           In glibc up to and including 2.19:
               _BSD_SOURCE

DESCRIPTION

       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 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 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.

   rexec_af()
       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).

VERSIONS

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

ATTRIBUTES

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

       ┌────────────────────┬───────────────┬───────────┐
       │Interface           │ Attribute     │ Value     │
       ├────────────────────┼───────────────┼───────────┤
       │rexec(), rexec_af() │ Thread safety │ MT-Unsafe │
       └────────────────────┴───────────────┴───────────┘

CONFORMING TO

       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.

BUGS

       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.

SEE ALSO

       rcmd(3), rexecd(8)

COLOPHON

       This page is part of release 5.10 of  the  Linux  man-pages  project.   A  description  of  the  project,
       information   about   reporting   bugs,   and   the  latest  version  of  this  page,  can  be  found  at
       https://www.kernel.org/doc/man-pages/.