OSF

NAME

rcmd − Allows execution of commands on a remote host

LIBRARY

Standard C Library (libc.a)

SYNOPSIS

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

PARAMETERS

hostSpecifies the name of a remote host that is listed in the /etc/hosts file.  If the specified name of the host is not found in this file, the rcmd() function fails. 

portSpecifies the well-known port to use for the connection.  The /etc/services file contains the DARPA Internet services, their ports, and socket types. 

local_userPoints to user names that are valid at the local host.  Any valid user name can be given. 

remote_userPoints to user names that are valid at the remote host.  Any valid user name can be given. 

commandSpecifies the name of the command to be executed at the remote host. 

err_file_descSpecifies an integer that controls the set up of communications channels.  Integer options are as follows:

       •If a nonzero integer is specified, an auxiliary channel to a control process is set up, and the error_file_desc parameter points to the file descriptor for the channel.  The control process provides diagnostic output from the remote command on this channel and also accepts bytes as signal numbers to be forwarded to the process group of the command. 

       •If 0 (zero) is specified, the standard error (stderr) of the remote command is the same as the standard output (stdout).  No provision is made for sending arbitrary signals to the remote process.  However, it is possible to send out-of-band data to the remote command. 

DESCRIPTION

The rcmd() (remote command) function allows execution of certain commands on a remote host that supports the rshd(), rlogin(), and rpc() functions, 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 connection 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. 

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. 

RETURN VALUES

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

FILES

/etc/services
Contains the service names, ports, and socket types.

/etc/hostsContains hostnames and their addresses for hosts in a network. 

/etc/resolv.conf
Contains the name server and domain name.

RELATED INFORMATION

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

Commands: rlogind(8), rshd(8), named(8)