utmp.5

UNIX v6源代码 这几乎是最经典的unix版本 unix操作系统设计和莱昂氏unix源代码分析都是用的该版

.th UTMP V 9/10/73
.sh NAME
utmp \*- user information
.sh DESCRIPTION
This
file allows one to discover information about who is currently
using UNIX.
The file is binary; each entry is 16(10) bytes long.
The first eight bytes contain a user's login name or
are null if the table slot is unused.
The low order byte of the next word contains the last
character of a typewriter name.
The next two words contain the user's login time.
The last word is unused.
.sh FILES
/etc/utmp
.sh "SEE ALSO"
init (VIII) and login (I), which maintain the file;
who (I), which interprets it.