rcmd(3) 						     Library Functions Manual							   rcmd(3)

NAME

       rcmd,  rcmd_r - Allow execution of commands on a remote host

LIBRARY

       Standard C Library (libc.a)

SYNOPSIS

       #include <sys/types.h> #include <netdb.h> #include <unistd.h>

       int rcmd(      char **host,	u_short port,	   char *local_user,	  char *remote_user,	  char *command,      int *err_file_desc);

       The  following  function  is  supported	in  order  to maintain backward compatibility with previous versions of the operating system.  int
       rcmd_r(	    char **host,      u_short port,	 char *local_user,	char *remote_user,	char  *command,       int  *err_file_desc,
	    struct hostent_data *host_data);

PARAMETERS

       Specifies  the name of a remote host that is listed in the /etc/hosts file.  The function sets the host parameter to be the fully qualified
       hostname.  Specifies the well-known port to use for the connection.  The /etc/services file contains the  DARPA	Internet  services,  their
       ports, and socket types.  Points to usernames that are valid at the local host.	Any valid username can be given.  Points to usernames that
       are valid at the remote host.  Any valid username can be given.	Specifies the name of the command to  be  executed  at	the  remote  host.
       Points to an address used by rcmd() to store a pointer to the file descriptor for a channel used by the remote process to write stderr mes-
       sages and to accept bytes as signal numbers to be forwarded to the process group of the command.

       If a null pointer is specified, the standard error (stderr) of the remote command is the same as the standard output (stdout).	No  provi-
       sion  is made for sending arbitrary signals to the remote process.  However, it is possible to send out-of-band data to the remote command.
       Per-thread data for reentrant version.

DESCRIPTION

       The rcmd() (remote command) function allows execution of certain commands on a remote host.  For example, the rcmd() function  is  used	by
       rsh and rlogin, among others.

       The  rcmd() function looks up a host via the name server or, if the local name server is not running, via the /etc/hosts file.  If the con-
       nection succeeds, a socket in the Internet domain of type SOCK_STREAM is returned to the calling process and given to the remote command as
       standard input (stdin) and standard output (stdout).

       Always  specify	the  host  name.  If the local domain and remote domain are the same, specifying the domain parts is optional.	The rcmd()
       function returns the fully qualified hostname in the host parameter. To reuse the host name in another  rcmd()  call,  you  should  make  a
       string copy of the host parameter.  For example: rcmd ( &host, .... ); first_host = strdup(host); ...  rcmd ( &host, .... );

       Only  processes	with an effective user ID of root user can use the rcmd() function.  An authentication scheme based on remote port numbers
       is used to verify permissions.  Ports in the range from 0 to 1023 can only be used by a root user.

NOTES

       The rcmd_r() function is the reentrant version of rcmd(). It is supported in order to maintain backward compatibility  with  previous  ver-
       sions of the operating system.

       The netdb.h header file defines the hostent_data structures.

RETURN VALUES

       Upon  successful  completion,  the  rcmd() function returns a valid socket descriptor.  The function returns a value of -1 if the effective
       user ID of the calling process is not root user, if the function fails to resolve the host, or if it encounters a socket connection error.

FILES

       Contains the service names, ports, and socket types.  Contains hostnames and their addresses for the hosts in a network.  Contains the name
       server and the domain name.

RELATED INFORMATION

       Functions: gethostname(2), rresvport(3), rresvport_af(3), ruserok(3), sethostname(2).

       Commands: rlogin(1), rsh(1).  delim off

																	   rcmd(3)