LOGIN
NAME
login, logout - write utmp and wtmp entries
SYNOPSIS
#include <utmp.h>
I void login(const struct utmp * ut );
I int logout(const char * ut_line );
Link with -lutil.
DESCRIPTION
The utmp file records who is currently using the system.
The wtmp file records all logins and logouts.
See
utmp(5).
The function
R login ()
takes the supplied struct utmp,
R ut ,
and writes it to both utmp and wtmp file.
The function
R logout ()
clears the entry in the utmp file again.
GNU Details
More precisely,
R login ()
takes the argument
ut
struct, fills the field
ut->ut_type
(if there is such a field) with the value
R USER_PROCESS ,
and fills the field
ut->ut_pid
(if there is such a field) with the process ID of the calling process.
Then it tries to fill the field
R ut->ut_line .
It takes the first of
stdin,
stdout,
stderr
that is a tty, and
stores the corresponding pathname minus a possible leading
/dev/
into this field, and then writes the struct to the utmp file.
On the other hand, if no tty name was found, this field is filled with "???"
and the struct is not written to the utmp file.
After this, the struct is written to the wtmp file.
The
R logout ()
function searches the utmp file for an entry matching the
ut_line
argument.
If a record is found, it is updated by zeroing out the
ut_name
and
ut_host
fields, updating the
ut_tv
timestamp field and setting
ut_type
(if there is such a field) to
R DEAD_PROCESS .
RETURN VALUE
The
R logout ()
function returns 1 if the entry was successfully written to the
database, or 0 if an error occurred.
FILES
/var/run/utmp
user accounting database, configured through
_PATH_UTMP
in
<paths.h>
/var/log/wtmp
user accounting log file, configured through
_PATH_WTMP
in
<paths.h>
CONFORMING TO
Not in POSIX.1-2001.
Present on the BSDs.
NOTES
Note that the
member
ut_user
of
struct utmp
is called
ut_name
in BSD.
Therefore,
ut_name
is defined as an alias for
ut_user
in
R <utmp.h> .
SEE ALSO
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