1WRITE(1P) POSIX Programmer's Manual WRITE(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
13 write — write to another user
14
16 write user_name [terminal]
17
19 The write utility shall read lines from the standard input and write
20 them to the terminal of the specified user. When first invoked, it
21 shall write the message:
22 Message from sender-login-id (sending-terminal) [date]...
24 to user_name. When it has successfully completed the connection, the
26 sender's terminal shall be alerted twice to indicate that what the
27 sender is typing is being written to the recipient's terminal.
28 If the recipient wants to reply, this can be accomplished by typing:
30 write sender-login-id [sending-terminal]
32 upon receipt of the initial message. Whenever a line of input as delim‐
34 ited by an NL, EOF, or EOL special character (see the Base Definitions
35 volume of POSIX.1‐2008, Chapter 11, General Terminal Interface) is
36 accumulated while in canonical input mode, the accumulated data shall
37 be written on the other user's terminal. Characters shall be processed
38 as follows:
39 * Typing <alert> shall write the <alert> character to the recipient's
41 terminal.
42 * Typing the erase and kill characters shall affect the sender's ter‐
44 minal in the manner described by the termios interface in the Base
45 Definitions volume of POSIX.1‐2008, Chapter 11, General Terminal
46 Interface.
47 * Typing the interrupt or end-of-file characters shall cause write to
49 write an appropriate message ("EOT\n" in the POSIX locale) to the
50 recipient's terminal and exit.
51 * Typing characters from LC_CTYPE classifications print or space
53 shall cause those characters to be sent to the recipient's termi‐
54 nal.
55 * When and only when the stty iexten local mode is enabled, the exis‐
57 tence and processing of additional special control characters and
58 multi-byte or single-byte functions is implementation-defined.
59 * Typing other non-printable characters shall cause implementation-
61 defined sequences of printable characters to be written to the
62 recipient's terminal.
63 To write to a user who is logged in more than once, the terminal argu‐
65 ment can be used to indicate which terminal to write to; otherwise, the
66 recipient's terminal is selected in an implementation-defined manner
67 and an informational message is written to the sender's standard out‐
68 put, indicating which terminal was chosen.
69 Permission to be a recipient of a write message can be denied or
71 granted by use of the mesg utility. However, a user's privilege may
72 further constrain the domain of accessibility of other users' termi‐
73 nals. The write utility shall fail when the user lacks appropriate
74 privileges to perform the requested action.
75
77 None.
78
80 The following operands shall be supported:
81 user_name Login name of the person to whom the message shall be writ‐
83 ten. The application shall ensure that this operand is of the
84 form returned by the who utility.
85 terminal Terminal identification in the same format provided by the
87 who utility.
88
90 Lines to be copied to the recipient's terminal are read from standard
91 input.
92
94 None.
95
97 The following environment variables shall affect the execution of
98 write:
99 LANG Provide a default value for the internationalization vari‐
101 ables that are unset or null. (See the Base Definitions vol‐
102 ume of POSIX.1‐2008, Section 8.2, Internationalization Vari‐
103 ables for the precedence of internationalization variables
104 used to determine the values of locale categories.)
105 LC_ALL If set to a non-empty string value, override the values of
107 all the other internationalization variables.
108 LC_CTYPE Determine the locale for the interpretation of sequences of
110 bytes of text data as characters (for example, single-byte as
111 opposed to multi-byte characters in arguments and input
112 files). If the recipient's locale does not use an LC_CTYPE
113 equivalent to the sender's, the results are undefined.
114 LC_MESSAGES
116 Determine the locale that should be used to affect the format
117 and contents of diagnostic messages written to standard error
118 and informative messages written to standard output.
119 NLSPATH Determine the location of message catalogs for the processing
121 of LC_MESSAGES.
122
124 If an interrupt signal is received, write shall write an appropriate
125 message on the recipient's terminal and exit with a status of zero. It
126 shall take the standard action for all other signals.
127
129 An informational message shall be written to standard output if a
130 recipient is logged in more than once.
131
133 The standard error shall be used only for diagnostic messages.
134
136 The recipient's terminal is used for output.
137
139 None.
140
142 The following exit values shall be returned:
143 0 Successful completion.
145 >0 The addressed user is not logged on or the addressed user denies
147 permission.
148
150 Default.
151 The following sections are informative.
153
155 The talk utility is considered by some users to be a more usable util‐
156 ity on full-screen terminals.
157
159 None.
160
162 The write utility was included in this volume of POSIX.1‐2008 since it
163 can be implemented on all terminal types. The standard developers con‐
164 sidered the talk utility, which cannot be implemented on certain termi‐
165 nals, to be a ``better'' communications interface. Both of these pro‐
166 grams are in widespread use on historical implementations. Therefore,
167 the standard developers decided that both utilities should be speci‐
168 fied.
169 The format of the terminal name is unspecified, but the descriptions of
171 ps, talk, who, and write require that they all use or accept the same
172 format.
173
175 None.
176
178 mesg, talk, who
179 The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
181 Variables, Chapter 11, General Terminal Interface
182
184 Portions of this text are reprinted and reproduced in electronic form
185 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
186 -- Portable Operating System Interface (POSIX), The Open Group Base
187 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
188 cal and Electronics Engineers, Inc and The Open Group. (This is
189 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
190 event of any discrepancy between this version and the original IEEE and
191 The Open Group Standard, the original IEEE and The Open Group Standard
192 is the referee document. The original Standard can be obtained online
193 at http://www.unix.org/online.html .
194 Any typographical or formatting errors that appear in this page are
196 most likely to have been introduced during the conversion of the source
197 files to man page format. To report such errors, see https://www.ker‐
198 nel.org/doc/man-pages/reporting_bugs.html .
199IEEE/The Open Group 2013 WRITE(1P)