Page 1139
| rfc931 = timeout_in_seconds | |
| rfc931 (no argument) | Look up the remote user name with the RFC 931 (ident and so on) protocol. This option is silently ignored in case of services based on transports other than TCP. It requires that the client system runs an RFC 931 (ident and so on) compliant daemon and may cause noticeable delays with connections from non-UNIX hosts. The time-out period is optional. If no time-out is specified, a default value is taken. |
DIAGNOSTICS
When a syntax error is found in an access control rule, the error is reported to the syslog daemon; further options will be ignored, and service is denied.
SEE ALSO
hosts_access(5), the default access control language
AUTHOR
Wietse Venema (wietse@wzv.win.tue.nl), Department of Mathematics and Computing Science, Eindhoven University of Technology, Den Dolech 2, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
inittab—Format of the inittab file used by the SysV-compatible init process.
DESCRIPTION
The inittab file describes which processes are started at bootup and during normal operation (such as /etc/rc, gettys). init distinguishes multiple run levels, of which each can have its own set of processes that are started. Valid runlevels are 0_6 and A, B, and C for ondemand entries. An entry in the inittab file has the following format:
id:runlevels:action:process
Lines beginning with # are ignored.
| id | A unique two-character-sequence which identifies an entry in inittab. |
| Note: For gettys or other login processes, the id field should be the tty suffix of the corresponding tty, such as 1 for tty1. Otherwise, the login accounting will not work correctly. This is a bug in login and will be fixed. | |
| runlevels | Describes in which run levels the specified action should be taken. |
| action | Describes which action should be taken. |
| process | Specifies the process to be executed. If the process field starts with a + character, init will not do utmp and wtmp accounting for that process. This is needed for gettys that insist on doing their own utmp/wtmp housekeeping. This is also a historic bug. |
Valid actions are
| respawn | The process will be restarted whenever it terminates (such as getty). |
| wait | The process will be started once when the specified run level is entered and init will wait for its termination. |
| once | The process will be executed once when the specified run level is entered. |
| boot | The process will be executed during system boot. The run level field is ignored. |
Page 1140
| bootwait | The process will be executed during system boot while init waits for its termination (such as /etc/rc). The runlevel field is ignored. |
| off | This does nothing. |
| ondemand | A process marked with ondemand will be executed whenever the specified ondemand run level is called. However, no runlevel change will occur. |
| initdefault | An initdefault-entry specifies the run level that should be entered after system boot. If none exists, init will ask for a runlevel on the console. |
| sysinit | The process will be executed during system boot. It will be executed before any boot or bootwait entries. |
| powerwait | The process will be executed when init receives the SIGPWR signal, indicating that there is something wrong with the power. init will wait for the process to finish before continuing. |
| powerfail | As powerwait but init will not wait for the processes completion. |
| powerokwait | The process will be executed when init receives the SIGPWR signal, provided there is a file called /etc/powerstatus containing the word OK. This means that the power has come back again. |
| ctrlaltdel | The process will be executed when init receives the SIGINT signal. This means that someone on the system console pressed the Ctrl+Alt+Del key combination. Typically, one wants to execute some sort of shutdown either to get into single_user level or to reboot the machine. |
The runlevel field may contain multiple characters for different run levels, such as 123 if the process should be started in run levels 1, 2 and 3. Ondemand entries may contain an A, B, or C. The runlevel field of sysinit, boot, and bootwait entries are ignored.
When the run level is changed, any running processes that are not specified for the new run level are killed, first with SIGTERM and then with SIGKILL.
EXAMPLES
This is an example of an inittab that resembles the old Linux inittab:
# inittab for linux id:1:initdefault: rc::bootwait:/etc/rc 1:1:respawn:/etc/getty 9600 tty1 2:1:respawn:/etc/getty 9600 tty2 3:1:respawn:/etc/getty 9600 tty3 4:1:respawn:/etc/getty 9600 tty4
This inittab file executes /etc/rc during boot and starts gettys on tty1_tty4.
A more elaborate inittab with different run levels (see the comments inside) is
#Level to run in id:4:initdefault: ud::boot:/etc/update rc::bootwait:/etc/rc cr::boot:/etc/crond # # level 1: getty on tty1 # level 2: getty on tty1-4 # level 3: tty1-4, dialin via modem(ttys2) # level 4: tty1-4, ttyb # mr:126:once:/usr/bin/nodialin mi:345:once:/usr/bin/dialin 1:1234:respawn:/etc/getty 9600 tty1 2:234:respawn:/etc/getty 9600 tty2 3:234:respawn:/etc/getty 9600 tty3