NAME

       rexec, rexec_af - return stream to a remote command

SYNOPSIS

       #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);

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 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  4.04  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
       http://www.kernel.org/doc/man-pages/.