NAME

       rexec, rexec_af - return stream to a remote command

SYNOPSIS

       #include <netdb.h>

       int rexec(char **restrict ahost, int inport,
                 const char *restrict user, const char *restrict passwd,
                 const char *restrict cmd, int *restrict fd2p);
       int rexec_af(char **restrict ahost, int inport,
                 const char *restrict user, const char *restrict passwd,
                 const char *restrict cmd, int *restrict 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 5.13 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/.