Ausam/doc/man/man5/utmp.5

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including files from this version of Unix. 
.th UTMP V 9/4/78
.sh NAME
utmp \*- user information
.sh DESCRIPTION
This
file allows one to discover information about who is currently
using UNIX.
.s3
.mc |
The file is binary
with entries for all possible terminals.
The format of each entry is described by the C-structure declaration
.it utmp
in 
.it /usr/include/utmp.h.
.fl
.mc
.sh FILES
/etc/utmp
.br
.mc |
/usr/include/utmp.h
.mc
.sh "SEE ALSO"
.mc |
init (VIII) and getty (VIII), which maintain the file;
.fl
.mc
.br
who (I), which interprets it.