mirror of https://github.com/mkerrisk/man-pages
312 lines
9.2 KiB
Groff
312 lines
9.2 KiB
Groff
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "WHO" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" who
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.SH NAME
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who \- display who is on the system
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.SH SYNOPSIS
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.LP
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\fBwho\fP \fB[\fP\fB-mTu\fP\fB]\fP\fB
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.br
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.sp
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\fP
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.LP
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\fBwho\fP
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\fB[\fP\fB-mu\fP\fB]\fP\fB-s\fP\fB[\fP\fB-bHlprt\fP\fB][\fP\fIfile\fP\fB]\fP\fB
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.br
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.sp
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who\fP \fB[\fP\fB-mTu\fP\fB][\fP\fB-abdHlprt\fP\fB][\fP\fIfile\fP\fB]\fP\fB
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.br
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.sp
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who -q\fP \fB[\fP\fIfile\fP\fB]\fP\fB
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.br
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.sp
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who am i
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.br
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.sp
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who am I \fP
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\fB
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fIwho\fP utility shall list various pieces of information about
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accessible users. The domain of accessibility is
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implementation-defined.
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.LP
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Based on the options given, \fIwho\fP can also list the user's name,
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terminal line, login time, elapsed time since activity
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occurred on the line, and the process ID of the command interpreter
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for each current system user.
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.SH OPTIONS
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.LP
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The \fIwho\fP utility shall conform to the Base Definitions volume
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of IEEE\ Std\ 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
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.LP
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The following options shall be supported. The metavariables, such
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as <\fIline\fP>, refer to fields described in the
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STDOUT section.
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.TP 7
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\fB-a\fP
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Process the implementation-defined database or named file with the
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\fB-b\fP, \fB-d\fP, \fB-l\fP, \fB-p\fP, \fB-r\fP,
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\fB-t\fP, \fB-T\fP and \fB-u\fP options turned on.
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.TP 7
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\fB-b\fP
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Write the time and date of the last reboot.
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.TP 7
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\fB-d\fP
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Write a list of all processes that have expired and not been respawned
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by the \fIinit\fP system process. The <\fIexit\fP>
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field shall appear for dead processes and contain the termination
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and exit values of the dead process. This can be useful in
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determining why a process terminated.
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.TP 7
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\fB-H\fP
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Write column headings above the regular output.
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.TP 7
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\fB-l\fP
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(The letter ell.) List only those lines on which the system is waiting
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for someone to login. The <\fIname\fP> field shall be
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\fBLOGIN\fP in such cases. Other fields shall be the same as for user
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entries except that the <\fIstate\fP> field does not
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exist.
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.TP 7
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\fB-m\fP
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Output only information about the current terminal.
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.TP 7
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\fB-p\fP
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List any other process that is currently active and has been previously
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spawned by \fIinit\fP.
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.TP 7
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\fB-q\fP
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(Quick.) List only the names and the number of users currently logged
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on. When this option is used, all other options shall be
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ignored.
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.TP 7
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\fB-r\fP
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Write the current \fIrun-level\fP of the \fIinit\fP process.
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.TP 7
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\fB-s\fP
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List only the <\fIname\fP>, <\fIline\fP>, and <\fItime\fP> fields.
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This is the default case.
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.TP 7
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\fB-t\fP
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Indicate the last change to the system clock.
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.TP 7
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\fB-T\fP
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Show the state of each terminal, as described in the STDOUT section.
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.TP 7
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\fB-u\fP
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Write "idle time" for each displayed user in addition to any other
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information. The idle time is the time since any activity
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occurred on the user's terminal. The method of determining this is
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unspecified. \ This option
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shall list only those users who are currently logged in. The <\fIname\fP>
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is the user's login name. The <\fIline\fP>
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is the name of the line as found in the directory \fB/dev\fP. The
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<\fItime\fP> is the time that the user logged in. The
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<\fIactivity\fP> is the number of hours and minutes since activity
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last occurred on that particular line. A dot indicates
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that the terminal has seen activity in the last minute and is therefore
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"current". If more than twenty-four hours have elapsed or
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the line has not been used since boot time, the entry shall be marked
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<\fIold\fP>. This field is useful when trying to
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determine whether a person is working at the terminal or not. The
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<\fIpid\fP> is the process ID of the user's login process.
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.sp
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.SH OPERANDS
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.LP
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The following operands shall be supported:
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.TP 7
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\fBam\ i\fP,\ \fBam\ I\fP
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In the POSIX locale, limit the output to describing the invoking user,
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equivalent to the \fB-m\fP option. The \fBam\fP and
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\fBi\fP or \fBI\fP must be separate arguments.
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.TP 7
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\fIfile\fP
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Specify a pathname of a file to substitute for the implementation-defined
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database of logged-on users that \fIwho\fP uses by
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default.
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.sp
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.SH STDIN
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.LP
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Not used.
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.SH INPUT FILES
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.LP
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None.
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.SH ENVIRONMENT VARIABLES
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.LP
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The following environment variables shall affect the execution of
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\fIwho\fP:
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.TP 7
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\fILANG\fP
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Provide a default value for the internationalization variables that
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are unset or null. (See the Base Definitions volume of
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IEEE\ Std\ 1003.1-2001, Section 8.2, Internationalization Variables
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for
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the precedence of internationalization variables used to determine
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the values of locale categories.)
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.TP 7
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\fILC_ALL\fP
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If set to a non-empty string value, override the values of all the
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other internationalization variables.
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.TP 7
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\fILC_CTYPE\fP
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Determine the locale for the interpretation of sequences of bytes
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of text data as characters (for example, single-byte as
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opposed to multi-byte characters in arguments).
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.TP 7
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\fILC_MESSAGES\fP
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Determine the locale that should be used to affect the format and
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contents of diagnostic messages written to standard
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error.
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.TP 7
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\fILC_TIME\fP
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Determine the locale used for the format and contents of the date
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and time strings.
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.TP 7
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\fINLSPATH\fP
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Determine the location of message catalogs for the processing of \fILC_MESSAGES
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\&.\fP
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.TP 7
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\fITZ\fP
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Determine the timezone used when writing date and time information.
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If \fITZ\fP is unset or null, an unspecified default
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timezone shall be used.
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.sp
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.SH ASYNCHRONOUS EVENTS
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.LP
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Default.
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.SH STDOUT
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.LP
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The \fIwho\fP utility shall write its default format to the standard
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output in an implementation-defined format, subject only
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to the requirement of containing the information described above.
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.LP
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XSI-conformant systems shall write the default information to the
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standard output in the following general format:
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.sp
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.RS
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.nf
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\fB<\fP\fIname\fP\fB>\fP\fB[\fP\fB<\fP\fIstate\fP\fB>\fP\fB]\fP\fB<\fP\fIline\fP\fB><\fP\fItime\fP\fB>\fP\fB[\fP\fB<\fP\fIactivity\fP\fB>\fP\fB][\fP\fB<\fP\fIpid\fP\fB>\fP\fB][\fP\fB<\fP\fIcomment\fP\fB>\fP\fB][\fP\fB<\fP\fIexit\fP\fB>\fP\fB]\fP \fB
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\fP
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.fi
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.RE
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.LP
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The following format shall be used for the \fB-T\fP option:
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.sp
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.RS
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.nf
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\fB"%s %c %s %s\\n" <\fP\fIname\fP\fB>, <\fP\fIterminal state\fP\fB>, <\fP\fIterminal name\fP\fB>,
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<\fP\fItime of login\fP\fB>
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\fP
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.fi
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.RE
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.LP
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where <\fIterminal\ state\fP> is one of the following characters:
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.TP 7
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\fB+\fP
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The terminal allows write access to other users.
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.TP 7
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\fB-\fP
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The terminal denies write access to other users.
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.TP 7
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\fB?\fP
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The terminal write-access state cannot be determined.
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.sp
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.LP
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In the POSIX locale, the <\fItime\ of\ login\fP> shall be equivalent
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in format to the output of:
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.sp
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.RS
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.nf
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\fBdate +"%b %e %H:%M"
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\fP
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.fi
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.RE
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.LP
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If the \fB-u\fP option is used with \fB-T\fP, the idle time shall
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be added to the end of the previous format in an unspecified
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format.
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.SH STDERR
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.LP
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The standard error shall be used only for diagnostic messages.
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.SH OUTPUT FILES
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.LP
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None.
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.SH EXTENDED DESCRIPTION
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.LP
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None.
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.SH EXIT STATUS
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.LP
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The following exit values shall be returned:
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.TP 7
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\ 0
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Successful completion.
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.TP 7
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>0
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An error occurred.
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.sp
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.SH CONSEQUENCES OF ERRORS
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.LP
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Default.
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.LP
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\fIThe following sections are informative.\fP
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.SH APPLICATION USAGE
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.LP
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The name \fIinit\fP used for the system process is the most commonly
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used on historical systems, but it may vary.
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.LP
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The "domain of accessibility" referred to is a broad concept that
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permits interpretation either on a very secure basis or even
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to allow a network-wide implementation like the historical \fIrwho\fP.
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.SH EXAMPLES
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.LP
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None.
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.SH RATIONALE
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.LP
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Due to differences between historical implementations, the base options
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provided were a compromise to allow users to work with
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those functions. The standard developers also considered removing
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all the options, but felt that these options offered users
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valuable functionality. Additional options to match historical systems
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are available on XSI-conformant systems.
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.LP
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It is recognized that the \fIwho\fP command may be of limited usefulness,
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especially in a multi-level secure environment. The
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standard developers considered, however, that having some standard
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method of determining the "accessibility" of other users would
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aid user portability.
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.LP
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No format was specified for the default \fIwho\fP output for systems
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not supporting the XSI Extension. In such a user-oriented
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command, designed only for human use, this was not considered to be
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a deficiency.
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.LP
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The format of the terminal name is unspecified, but the descriptions
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of \fIps\fP, \fItalk\fP, and \fIwrite\fP require that they use the
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same
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format.
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.LP
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It is acceptable for an implementation to produce no output for an
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invocation of \fIwho\fP \fBmil\fP.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fImesg\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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