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
12 write - write to another user
13
15 write user_name [terminal]
16
18 The write utility shall read lines from the user's standard input and
19 write them to the terminal of another user. When first invoked, it
20 shall write the message:
21 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]
33 upon receipt of the initial message. Whenever a line of input as delim‐
35 ited by an NL, EOF, or EOL special character (see the Base Definitions
36 volume of IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface)
37 is accumulated while in canonical input mode, the accumulated data
38 shall be written on the other user's terminal. Characters shall be
39 processed as follows:
40 * Typing <alert> shall write the alert character to the recipient's
42 terminal.
43 * Typing the erase and kill characters shall affect the sender's ter‐
45 minal in the manner described by the termios interface in the Base
46 Definitions volume of IEEE Std 1003.1-2001, Chapter 11, General Ter‐
47 minal Interface.
48 * Typing the interrupt or end-of-file characters shall cause write to
50 write an appropriate message ( "EOT\n" in the POSIX locale) to the
51 recipient's terminal and exit.
52 * Typing characters from LC_CTYPE classifications print or space shall
54 cause those characters to be sent to the recipient's terminal.
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 the appropriate
74 privileges to perform the requested action.
75
77 None.
78
80 The following operands shall be supported:
81 user_name
83 Login name of the person to whom the message shall be written.
84 The application shall ensure that this operand is of the form
85 returned by the who utility.
86 terminal
88 Terminal identification in the same format provided by the who
89 utility.
90
93 Lines to be copied to the recipient's terminal are read from standard
94 input.
95
97 None.
98
100 The following environment variables shall affect the execution of
101 write:
102 LANG Provide a default value for the internationalization variables
104 that are unset or null. (See the Base Definitions volume of
105 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
106 ables for the precedence of internationalization variables used
107 to determine the values of locale categories.)
108 LC_ALL If set to a non-empty string value, override the values of all
110 the other internationalization variables.
111 LC_CTYPE
113 Determine the locale for the interpretation of sequences of
114 bytes of text data as characters (for example, single-byte as
115 opposed to multi-byte characters in arguments and input files).
116 If the recipient's locale does not use an LC_CTYPE equivalent to
117 the sender's, the results are undefined.
118 LC_MESSAGES
120 Determine the locale that should be used to affect the format
121 and contents of diagnostic messages written to standard error
122 and informative messages written to standard output.
123 NLSPATH
125 Determine the location of message catalogs for the processing of
126 LC_MESSAGES .
127
130 If an interrupt signal is received, write shall write an appropriate
131 message on the recipient's terminal and exit with a status of zero. It
132 shall take the standard action for all other signals.
133
135 An informational message shall be written to standard output if a
136 recipient is logged in more than once.
137
139 The standard error shall be used only for diagnostic messages.
140
142 The recipient's terminal is used for output.
143
145 None.
146
148 The following exit values shall be returned:
149 0 Successful completion.
151 >0 The addressed user is not logged on or the addressed user denies
153 permission.
154
157 Default.
158 The following sections are informative.
160
162 The talk utility is considered by some users to be a more usable util‐
163 ity on full-screen terminals.
164
166 None.
167
169 The write utility was included in this volume of IEEE Std 1003.1-2001
170 since it can be implemented on all terminal types. The standard devel‐
171 opers considered the talk utility, which cannot be implemented on cer‐
172 tain terminals, to be a "better" communications interface. Both of
173 these programs are in widespread use on historical implementations.
174 Therefore, the standard developers decided that both utilities should
175 be specified.
176 The format of the terminal name is unspecified, but the descriptions of
178 ps, talk, who, and write require that they all use or accept the same
179 format.
180
182 None.
183
185 mesg, talk, who, the Base Definitions volume of IEEE Std 1003.1-2001,
186 Chapter 11, General Terminal Interface
187
189 Portions of this text are reprinted and reproduced in electronic form
190 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
191 -- Portable Operating System Interface (POSIX), The Open Group Base
192 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
193 Electrical and Electronics Engineers, Inc and The Open Group. In the
194 event of any discrepancy between this version and the original IEEE and
195 The Open Group Standard, the original IEEE and The Open Group Standard
196 is the referee document. The original Standard can be obtained online
197 at http://www.opengroup.org/unix/online.html .
198IEEE/The Open Group 2003 WRITE(1P)