getttyent.3

早期freebsd实现

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.\"     @(#)getttyent.3	8.1 (Berkeley) 6/4/93
.\"
.Dd June 4, 1993
.Dt GETTTYENT 3
.Os BSD 4.3
.Sh NAME
.Nm getttyent ,
.Nm getttynam ,
.Nm setttyent ,
.Nm endttyent
.Nd get ttys file entry
.Sh SYNOPSIS
.Fd #include <ttyent.h>
.Ft struct ttyent *
.Fn getttyent
.Ft struct ttyent *
.Fn getttynam "char *name"
.Ft int
.Fn setttyent void
.Ft int
.Fn endttyent void
.Sh DESCRIPTION
The
.Fn getttyent ,
and
.Fn getttynam
functions
each return a pointer to an object, with the following structure,
containing the broken-out fields of a line from the tty description
file.
.Bd -literal
struct ttyent {
	char	*ty_name;	/* terminal device name */
	char	*ty_getty;	/* command to execute */
	char	*ty_type;	/* terminal type */
#define	TTY_ON		0x01	/* enable logins */
#define	TTY_SECURE	0x02	/* allow uid of 0 to login */
	int	ty_status;	/* flag values */
	char	*ty_window;	/* command for window manager */
	char	*ty_comment;	/* comment field */
};
.Ed
.Pp
The fields are as follows:
.Bl -tag -width ty_comment
.It Fa ty_name
The name of the character-special file.
.It Fa ty_getty
The name of the command invoked by
.Xr init 8
to initialize tty line characteristics.
.It Fa ty_type
The name of the default terminal type connected to this tty line.
.It Fa ty_status
A mask of bit fields which indicate various actions allowed on this
tty line.
The possible flags are as follows:
.Bl -tag -width TTY_SECURE
.It Dv TTY_ON
Enables logins (i.e.,
.Xr init 8
will start the command referenced by
.Fa ty_getty
on this entry).
.It Dv TTY_SECURE
Allow users with a uid of 0 to login on this terminal.
.El
.It Fa ty_window
The command to execute for a window system associated with the line.
.It Fa ty_comment
Any trailing comment field, with any leading hash marks (``#'') or
whitespace removed.
.El
.Pp
If any of the fields pointing to character strings are unspecified,
they are returned as null pointers.
The field
.Fa ty_status
will be zero if no flag values are specified.
.Pp
See
.Xr ttys 5
for a more complete discussion of the meaning and usage of the
fields.
.Pp
The
.Fn getttyent
function
reads the next line from the ttys file, opening the file if necessary.
The
.Fn setttyent
function
rewinds the file if open, or opens the file if it is unopened.
The
.Fn endttyent
function
closes any open files.
.Pp
The
.Fn getttynam
function
searches from the beginning of the file until a matching
.Fa name
is found
(or until
.Dv EOF
is encountered).
.Sh RETURN VALUES
The routines
.Fn getttyent
and
.Fn getttynam
return a null pointer on
.Dv EOF
or error.
The
.Fn setttyent
function
and
.Fn endttyent
return 0 on failure and 1 on success.
.Sh FILES
.Bl -tag -width /etc/ttys -compact
.It Pa /etc/ttys
.El
.Sh SEE ALSO
.Xr login 1 ,
.Xr ttyslot 3 ,
.Xr gettytab 5 ,
.Xr termcap 5 ,
.Xr ttys 5 ,
.Xr getty 8 ,
.Xr init 8
.Sh HISTORY
The
.Fn getttyent ,
.Fn getttynam ,
.Fn setttyent ,
and
.Fn endttyent
functions appeared in
.Bx 4.3 .
.Sh BUGS
These functions use static data storage;
if the data is needed for future use, it should be
copied before any subsequent calls overwrite it.