1WHO(1P) POSIX Programmer's Manual WHO(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 who - display who is on the system
13
15 who [-mTu]
16 who [-mu]-s[-bHlprt][file]
20 who [-mTu][-abdHlprt][file]
22 who -q [file]
24 who am i
26 who am I
28
31 The who utility shall list various pieces of information about accessi‐
32 ble users. The domain of accessibility is implementation-defined.
33 Based on the options given, who can also list the user's name, terminal
35 line, login time, elapsed time since activity occurred on the line, and
36 the process ID of the command interpreter for each current system user.
37
39 The who utility shall conform to the Base Definitions volume of
40 IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
41 The following options shall be supported. The metavariables, such as
43 <line>, refer to fields described in the STDOUT section.
44 -a Process the implementation-defined database or named file with
46 the -b, -d, -l, -p, -r, -t, -T and -u options turned on.
47 -b Write the time and date of the last reboot.
49 -d Write a list of all processes that have expired and not been
51 respawned by the init system process. The <exit> field shall
52 appear for dead processes and contain the termination and exit
53 values of the dead process. This can be useful in determining
54 why a process terminated.
55 -H Write column headings above the regular output.
57 -l (The letter ell.) List only those lines on which the system is
59 waiting for someone to login. The <name> field shall be LOGIN in
60 such cases. Other fields shall be the same as for user entries
61 except that the <state> field does not exist.
62 -m Output only information about the current terminal.
64 -p List any other process that is currently active and has been
66 previously spawned by init.
67 -q (Quick.) List only the names and the number of users currently
69 logged on. When this option is used, all other options shall be
70 ignored.
71 -r Write the current run-level of the init process.
73 -s List only the <name>, <line>, and <time> fields. This is the
75 default case.
76 -t Indicate the last change to the system clock.
78 -T Show the state of each terminal, as described in the STDOUT sec‐
80 tion.
81 -u Write "idle time" for each displayed user in addition to any
83 other information. The idle time is the time since any activity
84 occurred on the user's terminal. The method of determining this
85 is unspecified. This option shall list only those users who are
86 currently logged in. The <name> is the user's login name. The
87 <line> is the name of the line as found in the directory /dev.
88 The <time> is the time that the user logged in. The <activity>
89 is the number of hours and minutes since activity last occurred
90 on that particular line. A dot indicates that the terminal has
91 seen activity in the last minute and is therefore "current". If
92 more than twenty-four hours have elapsed or the line has not
93 been used since boot time, the entry shall be marked <old>. This
94 field is useful when trying to determine whether a person is
95 working at the terminal or not. The <pid> is the process ID of
96 the user's login process.
97
100 The following operands shall be supported:
101 am i, am I
103 In the POSIX locale, limit the output to describing the invoking
104 user, equivalent to the -m option. The am and i or I must be
105 separate arguments.
106 file Specify a pathname of a file to substitute for the implementa‐
108 tion-defined database of logged-on users that who uses by
109 default.
110
113 Not used.
114
116 None.
117
119 The following environment variables shall affect the execution of who:
120 LANG Provide a default value for the internationalization variables
122 that are unset or null. (See the Base Definitions volume of
123 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
124 ables for the precedence of internationalization variables used
125 to determine the values of locale categories.)
126 LC_ALL If set to a non-empty string value, override the values of all
128 the other internationalization variables.
129 LC_CTYPE
131 Determine the locale for the interpretation of sequences of
132 bytes of text data as characters (for example, single-byte as
133 opposed to multi-byte characters in arguments).
134 LC_MESSAGES
136 Determine the locale that should be used to affect the format
137 and contents of diagnostic messages written to standard error.
138 LC_TIME
140 Determine the locale used for the format and contents of the
141 date and time strings.
142 NLSPATH
144 Determine the location of message catalogs for the processing of
145 LC_MESSAGES .
146 TZ Determine the timezone used when writing date and time informa‐
148 tion. If TZ is unset or null, an unspecified default timezone
149 shall be used.
150
153 Default.
154
156 The who utility shall write its default format to the standard output
157 in an implementation-defined format, subject only to the requirement of
158 containing the information described above.
159 XSI-conformant systems shall write the default information to the stan‐
161 dard output in the following general format:
162 <name>[<state>]<line><time>[<activity>][<pid>][<comment>][<exit>]
165 The following format shall be used for the -T option:
167 "%s %c %s %s\n" <name>, <terminal state>, <terminal name>,
170 <time of login>
171 where <terminal state> is one of the following characters:
173 + The terminal allows write access to other users.
175 - The terminal denies write access to other users.
177 ? The terminal write-access state cannot be determined.
179 In the POSIX locale, the <time of login> shall be equivalent in format
182 to the output of:
183 date +"%b %e %H:%M"
186 If the -u option is used with -T, the idle time shall be added to the
188 end of the previous format in an unspecified format.
189
191 The standard error shall be used only for diagnostic messages.
192
194 None.
195
197 None.
198
200 The following exit values shall be returned:
201 0 Successful completion.
203 >0 An error occurred.
205
208 Default.
209 The following sections are informative.
211
213 The name init used for the system process is the most commonly used on
214 historical systems, but it may vary.
215 The "domain of accessibility" referred to is a broad concept that per‐
217 mits interpretation either on a very secure basis or even to allow a
218 network-wide implementation like the historical rwho.
219
221 None.
222
224 Due to differences between historical implementations, the base options
225 provided were a compromise to allow users to work with those functions.
226 The standard developers also considered removing all the options, but
227 felt that these options offered users valuable functionality. Addi‐
228 tional options to match historical systems are available on XSI-confor‐
229 mant systems.
230 It is recognized that the who command may be of limited usefulness,
232 especially in a multi-level secure environment. The standard developers
233 considered, however, that having some standard method of determining
234 the "accessibility" of other users would aid user portability.
235 No format was specified for the default who output for systems not sup‐
237 porting the XSI Extension. In such a user-oriented command, designed
238 only for human use, this was not considered to be a deficiency.
239 The format of the terminal name is unspecified, but the descriptions of
241 ps, talk, and write require that they use the same format.
242 It is acceptable for an implementation to produce no output for an
244 invocation of who mil.
245
247 None.
248
250 mesg
251
253 Portions of this text are reprinted and reproduced in electronic form
254 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
255 -- Portable Operating System Interface (POSIX), The Open Group Base
256 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
257 Electrical and Electronics Engineers, Inc and The Open Group. In the
258 event of any discrepancy between this version and the original IEEE and
259 The Open Group Standard, the original IEEE and The Open Group Standard
260 is the referee document. The original Standard can be obtained online
261 at http://www.opengroup.org/unix/online.html .
262IEEE/The Open Group 2003 WHO(1P)