rexec, rexec_r - Allow command execution on a remote host
#include <netdb.h> #include <unistd.h>
int *err_file_desc );
The following function is supported in order to maintain backward com‐
patibility with previous versions of the operating system: int rexec_r(
struct hostent_data *host_data );
Standard C Library (libc)
Contains the name of a remote host that is listed in the /etc/hosts
file or /etc/resolv.conffile. If the name of the host is not found in
either file, the rexec() fails. Specifies the well-known Internet port
to use for the connection. A pointer to the structure that contains
the necessary port can be obtained by issuing the following library
getservbyname("exec", "tcp") Points to a user ID that is valid
on the host. Points to the password of the specified user ID on
the host. Points to the name of the command to be executed at
the remote host. Specifies the file to which standard error
from the remote command is sent.
If the err_file_desc parameter is 0 (zero), the standard error
of the remote command is the same as standard output. No provi‐
sion is made for sending arbitrary signals to the remote
process. In this case, however, it may be possible to send out-
of-band data to the remote command.
If the err_file_desc parameter is nonzero, an auxiliary channel
to a control process is set up, and a descriptor for it is
placed in the err_file_desc parameter. The control process pro‐
vides 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. This diagnostic information does
not include remote authorization failure, since this connection
is set up after authorization has been verified. Per-thread
data for reentrant version.
The rexec() (remote execution) function allows the calling process to
execute commands on a remote host.
If the rexec() connection succeeds, a socket in the Internet domain of
type SOCK_STREAM is returned to the calling process and is given to the
remote command as standard input and standard output.
The user and passwd parameters specify a valid user ID and the associ‐
ated password for that user on the remote host. If the user and passwd
parameters are not supplied, the rexec() function takes the following
actions until finding a user ID and password to send to the remote
host: It searches the current environment for the user ID and password
on the remote host. It searches the user's home directory for a file
called $HOME/.netrc that contains a user ID and password. It prompts
the user for a user ID and password.
Note that action 3 does not apply when using rexec_r().
The rexec_r() function is the reentrant version of rexec(). It is sup‐
ported in order to maintain backward compatibility with previous ver‐
sions of the operating system. The netdb.h header file defines the
Upon successful completion, the system returns a socket descriptor to
the remote command. Otherwise, a value of -1 is returned, indicating
that the specified hostname does not exist.
Contains hostnames and their addresses for hosts in a network. This
file is used to resolve a hostname into an Internet address. Contains
the name server and domain name. Contains automatic login information.
Functions: getservbyname(3), rcmd(3), rresvport(3), ruserok(3).