rexec(3) Library Functions Manual rexec(3)
rexec, rexec_r - Allow command execution on a remote host
Standard C Library (libc.a)
int rexec( char **host, int port, char *user, char *passwd, 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
rexec_r( char **host, int port, char *user, char *passwd, char *command, int *err_file_desc, struct hos-
Contains the name of a remote host that is listed in the /etc/hosts file or /etc/resolv.conf file. 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 con-
tains the necessary port can be obtained by issuing the following library call: 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 provision 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 com-
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 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. 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 associated 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 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.
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).
Commands: rexecd(8). delim off