The
getttyent(), and
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.
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 */
#define TTY_LOCAL 0x04 /* set 'CLOCAL' on open (dev. specific) */
#define TTY_RTSCTS 0x08 /* set 'CRTSCTS' on open (dev. specific) */
#define TTY_SOFTCAR 0x10 /* ignore hardware carrier (dev. spec.) */
#define TTY_MDMBUF 0x20 /* set 'MDMBUF' on open (dev. specific) */
#define TTY_DTRCTS 0x40 /* set 'CDTRCTS' on open (dev. specific) */
int ty_status; /* flag values */
char *ty_window; /* command for window manager */
char *ty_comment; /* comment field */
char *ty_class; /* category of tty usage */
};
The fields are as follows:
ty_name
The name of the character-special file.
ty_getty
The name of the command invoked by
init(8) to initialize tty line characteristics.
ty_type
The name of the default terminal type connected to this tty line.
ty_status
A mask of bit fields which indicate various actions allowed on this tty line. The possible flags are as follows:
TTY_ON
Enables logins (i.e.,
init(8) will start the command referenced by
ty_getty on this entry).
TTY_SECURE
Allow users with a uid of 0 to login on this terminal.
TTY_LOCAL
If the terminal port's driver supports it, cause the line to be treated as ``local.''
TTY_MDMBUF
If the terminal port's driver supports it, use DTR/DCD hardware flow control on the line by default.
TTY_RTSCTS
If the terminal port's driver supports it, use full-duplex RTS/CTS hardware flow control on the line by default.
TTY_SOFTCAR
If the terminal port's driver supports it, ignore hardware carrier on the line.
ty_window
The command to execute for a window system associated with the line.
ty_comment
Any trailing comment field, with any leading hash marks (``#'') or whitespace removed.
ty_class
A key indexing into a termcap-style database (/etc/ttyclasses) of attributes for this class of tty. No attributes are currently defined or used, so there are currently no functions to retrieve them.
If any of the fields pointing to character strings are unspecified, they are returned as null pointers. The field
ty_status will be zero if no flag values are specified.
See
ttys(5) for a more complete discussion of the meaning and usage of the fields.
The
getttyent() function reads the next line from the ttys file, opening the file if necessary. The
setttyent() function rewinds the file if open, or opens the file if it is unopened. The
setttyentpath() function is equivalent to
setttyent() but accepts an additional argument to read the ttys information from an alternate file instead of the default location (defined in
_PATH_TTYS). The
endttyent() function closes any open files.
The
getttynam() function searches from the beginning of the file until a matching
name is found (or until
EOF is encountered).