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rwhod - system status server
The utility operates as both a producer and consumer of status information, unless the -l (listen mode) option is specified, in which case it acts as a consumer only. As a producer of information it periodically queries the state of the system and constructs status messages which are broadcasted or multicasted on a network. As a consumer of information, it listens for other servers' status messages, validating them, then recording them in a collection of files located in the directory /var/rwho
The following options are available:
If the optional ttl argument is supplied with the -m flag, will send IP multicast datagrams with a time-to-live of ttl via a SINGLE interface rather than all interfaces. ttl must be between 0 and 32 (or MAX_MULTICAST_SCOPE). Note that -m 1 is different from -m in that -m 1 specifies transmission on one interface only.
When -m is used without a ttl argument, the program accepts multicast reports from all multicast-capable interfaces. If a ttl argument is given, it accepts multicast reports from only one interface, the one on which reports are sent (which may be controlled via the host's routing table). Regardless of the -m option, the program accepts broadcast or unicast reports from all interfaces. Thus, this program will hear the reports of old, non-multicasting s but, if multicasting is used, those old s will not hear the reports generated by this program.
The server transmits and receives messages at the port indicated in the ``who'' service specification; see services(5). The messages sent and received, are of the form:
struct outmp {
char out_line[8]; /* tty name */
char out_name[8]; /* user id */
long out_time; /* time on */
};
struct whod {
char wd_vers;
char wd_type;
char wd_fill[2];
int wd_sendtime;
int wd_recvtime;
char wd_hostname[32];
int wd_loadav[3];
int wd_boottime;
struct whoent {
struct outmp we_utmp;
int we_idle;
} wd_we[1024 / sizeof (struct whoent)];
};
All fields are converted to network byte order prior to transmission. The load averages are as calculated by the w(1) program, and represent load averages over the 5, 10, and 15 minute intervals prior to a server's transmission; they are multiplied by 100 for representation in an integer. The host name included is that returned by the gethostname(3) system call, with any trailing domain name omitted. The array at the end of the message contains information about the users logged in to the sending machine. This information includes the contents of the utmp(5) entry for each non-idle terminal line and a value indicating the time in seconds since a character was last received on the terminal line.
Messages received by the rwho server are discarded unless they originated at an rwho server's port or the -i option was specified. In addition, if the host's name, as specified in the message, contains any unprintable ASCII characters, the message is discarded. Valid messages received by are placed in files named whod.hostname in the directory /var/rwho These files contain only the most recent message, in the format described above.
Status messages are generated approximately once every 3 minutes. The utility performs an nlist(3) on /boot/kernel/kernel every 30 minutes to guard against the possibility that this file is not the system image currently operating.
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Created 1996-2024 by Maxim Chirkov Добавить, Поддержать, Вебмастеру |