who.1

操作系统设计与实现源码

.TH WHO 1
.SH NAME
who \- print list of currently logged in users
.SH SYNOPSIS
\fBwho\fR [\fIfile\fR]\fR
.br
.de FL
.TP
\\fB\\$1\\fR
\\$2
..
.de EX
.TP 20
\\fB\\$1\\fR
# \\$2
..
.SH EXAMPLES
.EX "who   " "Print user names, terminals and times"
.SH DESCRIPTION
.PP
\fIWho\fR prints a list of currently logged in users.  For each one, 
the user name, terminal, and login time is printed.  
This program gets its information from the file \fI/etc/utmp\fR, which 
is updated by init and login.  
If the file does not exist, neither of these will create it, and 
\fIwho\fR will not work.  Note that if you decide to create an empty  
\fI/usr/adm/wtmp\fR to enable the login accounting, it will grow forever and 
eventually fill up your disk unless you manually truncate it from time to time.
If an optional file name is provided, the logins in that file will be printed.
.SH "SEE ALSO"
.BR utmp (5).