utmp.h -- Header File

Login accounting information
#include <utmp.h>

Header file <utmp.h> defines the types and constants that are used to
manipulate the system-adminstration  files /etc/utmp and /usr/adm/wtmp. The
former file describes every user  who is currently logged into your system;
the latter  records when each user  logged into your system  and logged out
again.

Each of these  files consists of records, each of  which has are objects of
type utmp, which <utmp.h> defines as follows:

struct  utmp {
    char ut_user[8];
    char ut_id[4];
    char ut_line[12];
    short ut_pid;
    short ut_type;
    struct exit_status {
        short e_termination;
        short e_exit;
    } ut_exit;
    time_t ut_time;
};

The following describes each field in utmp:

ut_user
     The login identifier of the user.

ut_id
     The user's identifier, as taken from /etc/init.

ut_line
     The device through which the user logged in.

ut_pid
     The process identifier of the user's shell.

ut_type
     Type of entry in this file.  This can be any of the following values:

          EMPTY          An empty entry
          RUN_LVL        Run level
          BOOT_TIME      Boot time
          OLD_TIME
          NEW_TIME
          INIT_PROCESS   Process spawned by init
          LOGIN_PROCESS  A getty waiting for a login
          USER_PROCESS   A user process
          DEAD_PROCESS
          ACCOUNTING

ut_exit
     The process's exit status.  It consists of the following fields:

     e_termination
          Process's termination status.

     e_exit
          Process's exit status.

ut_time
     The time the user logged on.

The following functions use this header file:

endutent().....Close the logging file.
getutent().....Read the next entry from /etc/utmp.
getutid()......Find an entry in /etc/utmp by login identifier.
getutline()....Find an entry in /etc/utmp by login device.
pututline()....Write a record into /etc/utmp.
setutent().....Rewind the input stream that is reading /etc/utmp
utmpname().....Manipulate a file other than /etc/utmp.

Each function is described in its own Lexicon entry.

Files

/etc/utmp
/usr/adm/wtmp

See Also

ac,
header files,
login,
utmp,
who,
wtmp

© 2012 by Stephen A. Ness