1MAILX(1P) POSIX Programmer's Manual MAILX(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 mailx — process messages
13
15 Send Mode
16 mailx [-s subject] address...
17 Receive Mode
19 mailx -e
20 mailx [-HiNn] [-F] [-u user]
22 mailx -f [-HiNn] [-F] [file]
24
26 The mailx utility provides a message sending and receiving facility. It
27 has two major modes, selected by the options used: Send Mode and
28 Receive Mode.
29 On systems that do not support the User Portability Utilities option,
31 an application using mailx shall have the ability to send messages in
32 an unspecified manner (Send Mode). Unless the first character of one or
33 more lines is <tilde> ('~'), all characters in the input message shall
34 appear in the delivered message, but additional characters may be
35 inserted in the message before it is retrieved.
36 On systems supporting the User Portability Utilities option, mail-
38 receiving capabilities and other interactive features, Receive Mode,
39 described below, also shall be enabled.
40 Send Mode
42 Send Mode can be used by applications or users to send messages from
43 the text in standard input.
44 Receive Mode
46 Receive Mode is more oriented towards interactive users. Mail can be
47 read and sent in this interactive mode.
48 When reading mail, mailx provides commands to facilitate saving, delet‐
50 ing, and responding to messages. When sending mail, mailx allows edit‐
51 ing, reviewing, and other modification of the message as it is entered.
52 Incoming mail shall be stored in one or more unspecified locations for
54 each user, collectively called the system mailbox for that user. When
55 mailx is invoked in Receive Mode, the system mailbox shall be the
56 default place to find new mail. As messages are read, they shall be
57 marked to be moved to a secondary file for storage, unless specific
58 action is taken. This secondary file is called the mbox and is normally
59 located in the directory referred to by the HOME environment variable
60 (see MBOX in the ENVIRONMENT VARIABLES section for a description of
61 this file). Messages shall remain in this file until explicitly
62 removed. When the -f option is used to read mail messages from sec‐
63 ondary files, messages shall be retained in those files unless specifi‐
64 cally removed. All three of these locations—system mailbox, mbox, and
65 secondary file—are referred to in this section as simply ``mailboxes'',
66 unless more specific identification is required.
67
69 The mailx utility shall conform to the Base Definitions volume of
70 POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
71 The following options shall be supported. (Only the -s subject option
73 shall be required on all systems. The other options are required only
74 on systems supporting the User Portability Utilities option.)
75 -e Test for the presence of mail in the system mailbox. The
77 mailx utility shall write nothing and exit with a successful
78 return code if there is mail to read.
79 -f Read messages from the file named by the file operand instead
81 of the system mailbox. (See also folder.) If no file operand
82 is specified, read messages from mbox instead of the system
83 mailbox.
84 -F Record the message in a file named after the first recipient.
86 The name is the login-name portion of the address found first
87 on the To: line in the mail header. Overrides the record
88 variable, if set (see Internal Variables in mailx).
89 -H Write a header summary only.
91 -i Ignore interrupts. (See also ignore.)
93 -n Do not initialize from the system default start-up file. See
95 the EXTENDED DESCRIPTION section.
96 -N Do not write an initial header summary.
98 -s subject
100 Set the Subject header field to subject. All characters in
101 the subject string shall appear in the delivered message. The
102 results are unspecified if subject is longer than {LINE_MAX}
103 - 10 bytes or contains a <newline>.
104 -u user Read the system mailbox of the login name user. This shall
106 only be successful if the invoking user has appropriate priv‐
107 ileges to read the system mailbox of that user.
108
110 The following operands shall be supported:
111 address Addressee of message. When -n is specified and no user start-
113 up files are accessed (see the EXTENDED DESCRIPTION section),
114 the user or application shall ensure this is an address to
115 pass to the mail delivery system. Any system or user start-up
116 files may enable aliases (see alias under Commands in mailx)
117 that may modify the form of address before it is passed to
118 the mail delivery system.
119 file A pathname of a file to be read instead of the system mailbox
121 when -f is specified. The meaning of the file option-argument
122 shall be affected by the contents of the folder internal
123 variable; see Internal Variables in mailx.
124
126 When mailx is invoked in Send Mode (the first synopsis line), standard
127 input shall be the message to be delivered to the specified addresses.
128 When in Receive Mode, user commands shall be accepted from stdin. If
129 the User Portability Utilities option is not supported, standard input
130 lines beginning with a <tilde> ('~') character produce unspecified
131 results.
132 If the User Portability Utilities option is supported, then in both
134 Send and Receive Modes, standard input lines beginning with the escape
135 character (usually <tilde> ('~')) shall affect processing as described
136 in Command Escapes in mailx.
137
139 When mailx is used as described by this volume of POSIX.1‐2017, the
140 file option-argument (see the -f option) and the mbox shall be text
141 files containing mail messages, formatted as described in the OUTPUT
142 FILES section. The nature of the system mailbox is unspecified; it need
143 not be a file.
144
146 Some of the functionality described in this section shall be provided
147 on implementations that support the User Portability Utilities option
148 as described in the text, and is not further shaded for this option.
149 The following environment variables shall affect the execution of
151 mailx:
152 DEAD Determine the pathname of the file in which to save partial
154 messages in case of interrupts or delivery errors. The
155 default shall be dead.letter in the directory named by the
156 HOME variable. The behavior of mailx in saving partial mes‐
157 sages is unspecified if the User Portability Utilities option
158 is not supported and DEAD is not defined with the value
159 /dev/null.
160 EDITOR Determine the name of a utility to invoke when the edit (see
162 Commands in mailx) or ~e (see Command Escapes in mailx) com‐
163 mand is used. The default editor is unspecified. On XSI-con‐
164 formant systems it is ed. The effects of this variable are
165 unspecified if the User Portability Utilities option is not
166 supported.
167 HOME Determine the pathname of the user's home directory.
169 LANG Provide a default value for the internationalization vari‐
171 ables that are unset or null. (See the Base Definitions vol‐
172 ume of POSIX.1‐2017, Section 8.2, Internationalization Vari‐
173 ables for the precedence of internationalization variables
174 used to determine the values of locale categories.)
175 LC_ALL If set to a non-empty string value, override the values of
177 all the other internationalization variables.
178 LC_CTYPE Determine the locale for the interpretation of sequences of
180 bytes of text data as characters (for example, single-byte as
181 opposed to multi-byte characters in arguments and input
182 files) and the handling of case-insensitive address and
183 header-field comparisons.
184 LC_TIME This variable may determine the format and contents of the
186 date and time strings written by mailx. This volume of
187 POSIX.1‐2017 specifies the effects of this variable only for
188 systems supporting the User Portability Utilities option.
189 LC_MESSAGES
191 Determine the locale that should be used to affect the format
192 and contents of diagnostic messages written to standard error
193 and informative messages written to standard output.
194 LISTER Determine a string representing the command for writing the
196 contents of the folder directory to standard output when the
197 folders command is given (see folders in Commands in mailx).
198 Any string acceptable as a command_string operand to the sh
199 -c command shall be valid. If this variable is null or not
200 set, the output command shall be ls. The effects of this
201 variable are unspecified if the User Portability Utilities
202 option is not supported.
203 MAILRC Determine the pathname of the user start-up file. The default
205 shall be .mailrc in the directory referred to by the HOME
206 environment variable. The behavior of mailx is unspecified if
207 the User Portability Utilities option is not supported and
208 MAILRC is not defined with the value /dev/null.
209 MBOX Determine a pathname of the file to save messages from the
211 system mailbox that have been read. The exit command shall
212 override this function, as shall saving the message explic‐
213 itly in another file. The default shall be mbox in the direc‐
214 tory named by the HOME variable. The effects of this variable
215 are unspecified if the User Portability Utilities option is
216 not supported.
217 NLSPATH Determine the location of message catalogs for the processing
219 of LC_MESSAGES.
220 PAGER Determine a string representing an output filtering or pagi‐
222 nation command for writing the output to the terminal. Any
223 string acceptable as a command_string operand to the sh -c
224 command shall be valid. When standard output is a terminal
225 device, the message output shall be piped through the command
226 if the mailx internal variable crt is set to a value less the
227 number of lines in the message; see Internal Variables in
228 mailx. If the PAGER variable is null or not set, the pagina‐
229 tor shall be either more or another paginator utility docu‐
230 mented in the system documentation. The effects of this
231 variable are unspecified if the User Portability Utilities
232 option is not supported.
233 SHELL Determine the name of a preferred command interpreter. The
235 default shall be sh. The effects of this variable are
236 unspecified if the User Portability Utilities option is not
237 supported.
238 TERM If the internal variable screen is not specified, determine
240 the name of the terminal type to indicate in an unspecified
241 manner the number of lines in a screenful of headers. If
242 TERM is not set or is set to null, an unspecified default
243 terminal type shall be used and the value of a screenful is
244 unspecified. The effects of this variable are unspecified if
245 the User Portability Utilities option is not supported.
246 TZ This variable may determine the timezone used to calculate
248 date and time strings written by mailx. If TZ is unset or
249 null, an unspecified default timezone shall be used.
250 VISUAL Determine a pathname of a utility to invoke when the visual
252 command (see Commands in mailx) or ~v command-escape (see
253 Command Escapes in mailx) is used. If this variable is null
254 or not set, the full-screen editor shall be vi. The effects
255 of this variable are unspecified if the User Portability
256 Utilities option is not supported.
257
259 When mailx is in Send Mode and standard input is not a terminal, it
260 shall take the standard action for all signals.
261 In Receive Mode, or in Send Mode when standard input is a terminal, if
263 a SIGINT signal is received:
264 1. If in command mode, the current command, if there is one, shall be
266 aborted, and a command-mode prompt shall be written.
267 2. If in input mode:
269 a. If ignore is set, mailx shall write "@\n", discard the current
271 input line, and continue processing, bypassing the message-
272 abort mechanism described in item 2b.
273 b. If the interrupt was received while sending mail, either when
275 in Receive Mode or in Send Mode, a message shall be written,
276 and another subsequent interrupt, with no other intervening
277 characters typed, shall be required to abort the mail message.
278 If in Receive Mode and another interrupt is received, a com‐
279 mand-mode prompt shall be written. If in Send Mode and another
280 interrupt is received, mailx shall terminate with a non-zero
281 status.
282 In both cases listed in item b, if the message is not empty:
284 i. If save is enabled and the file named by DEAD can be cre‐
286 ated, the message shall be written to the file named by
287 DEAD. If the file exists, the message shall be written to
288 replace the contents of the file.
289 ii. If save is not enabled, or the file named by DEAD cannot
291 be created, the message shall not be saved.
292 The mailx utility shall take the standard action for all other signals.
294
296 In command and input modes, all output, including prompts and messages,
297 shall be written to standard output.
298
300 The standard error shall be used only for diagnostic messages.
301
303 Various mailx commands and command escapes can create or add to files,
304 including the mbox, the dead-letter file, and secondary mailboxes. When
305 mailx is used as described in this volume of POSIX.1‐2017, these files
306 shall be text files, formatted as follows:
307 line beginning with From<space>
309 [one or more header-lines; see Commands in mailx]
310 empty line
311 [zero or more body lines
312 empty line]
313 [line beginning with From<space>...]
314 where each message begins with the From <space> line shown, preceded by
316 the beginning of the file or an empty line. (The From <space> line is
317 considered to be part of the message header, but not one of the header-
318 lines referred to in Commands in mailx; thus, it shall not be affected
319 by the discard, ignore, or retain commands.) The formats of the remain‐
320 der of the From <space> line and any additional header lines are
321 unspecified, except that none shall be empty. The format of a message
322 body line is also unspecified, except that no line following an empty
323 line shall start with From <space>; mailx shall modify any such user-
324 entered message body lines (following an empty line and beginning with
325 From <space>) by adding one or more characters to precede the 'F'; it
326 may add these characters to From <space> lines that are not preceded by
327 an empty line.
328 When a message from the system mailbox or entered by the user is not a
330 text file, it is implementation-defined how such a message is stored in
331 files written by mailx.
332
334 The functionality in the entire EXTENDED DESCRIPTION section shall be
335 provided on implementations supporting the User Portability Utilities
336 option. The functionality described in this section shall be provided
337 on implementations that support the User Portability Utilities option
338 (and the rest of this section is not further shaded for this option).
339 The mailx utility need not support for all character encodings in all
341 circumstances. For example, inter-system mail may be restricted to
342 7-bit data by the underlying network, 8-bit data need not be portable
343 to non-internationalized systems, and so on. Under these circumstances,
344 it is recommended that only characters defined in the ISO/IEC 646:1991
345 standard International Reference Version (equivalent to ASCII) 7-bit
346 range of characters be used.
347 When mailx is invoked using one of the Receive Mode synopsis forms, it
349 shall write a page of header-summary lines (if -N was not specified and
350 there are messages, see below), followed by a prompt indicating that
351 mailx can accept regular commands (see Commands in mailx); this is
352 termed command mode. The page of header-summary lines shall contain
353 the first new message if there are new messages, or the first unread
354 message if there are unread messages, or the first message. When mailx
355 is invoked using the Send Mode synopsis and standard input is a termi‐
356 nal, if no subject is specified on the command line and the asksub
357 variable is set, a prompt for the subject shall be written. At this
358 point, mailx shall be in input mode. This input mode shall also be
359 entered when using one of the Receive Mode synopsis forms and a reply
360 or new message is composed using the reply, Reply, followup, Followup,
361 or mail commands and standard input is a terminal. When the message is
362 typed and the end of the message is encountered, the message shall be
363 passed to the mail delivery software. Commands can be entered by begin‐
364 ning a line with the escape character (by default, <tilde> ('~')) fol‐
365 lowed by a single command letter and optional arguments. See Commands
366 in mailx for a summary of these commands. It is unspecified what effect
367 these commands will have if standard input is not a terminal when a
368 message is entered using either the Send Mode synopsis, or the Read
369 Mode commands reply, Reply, followup, Followup, or mail.
370 Note: For notational convenience, this section uses the default
372 escape character, <tilde>, in all references and examples.
373 At any time, the behavior of mailx shall be governed by a set of envi‐
375 ronmental and internal variables. These are flags and valued parame‐
376 ters that can be set and cleared via the mailx set and unset commands.
377 Regular commands are of the form:
379 [command] [msglist] [argument ...]
382 If no command is specified in command mode, next shall be assumed. In
384 input mode, commands shall be recognized by the escape character, and
385 lines not treated as commands shall be taken as input for the message.
386 In command mode, each message shall be assigned a sequential number,
388 starting with 1.
389 All messages have a state that shall affect how they are displayed in
391 the header summary and how they are retained or deleted upon termina‐
392 tion of mailx. There is at any time the notion of a current message,
393 which shall be marked by a '>' at the beginning of a line in the header
394 summary. When mailx is invoked using one of the Receive Mode synopsis
395 forms, the current message shall be the first new message, if there is
396 a new message, or the first unread message if there is an unread mes‐
397 sage, or the first message if there are any messages, or unspecified if
398 there are no messages in the mailbox. Each command that takes an
399 optional list of messages (msglist) or an optional single message (mes‐
400 sage) on which to operate shall leave the current message set to the
401 highest-numbered message of the messages specified, unless the command
402 deletes messages, in which case the current message shall be set to the
403 first undeleted message (that is, a message not in the deleted state)
404 after the highest-numbered message deleted by the command, if one
405 exists, or the first undeleted message before the highest-numbered mes‐
406 sage deleted by the command, if one exists, or to an unspecified value
407 if there are no remaining undeleted messages. All messages shall be in
408 one of the following states:
409 new The message is present in the system mailbox and has not been
411 viewed by the user or moved to any other state. Messages in
412 state new when mailx quits shall be retained in the system
413 mailbox.
414 unread The message has been present in the system mailbox for more
416 than one invocation of mailx and has not been viewed by the
417 user or moved to any other state. Messages in state unread
418 when mailx quits shall be retained in the system mailbox.
419 read The message has been processed by one of the following com‐
421 mands: ~f, ~m, ~F, ~M, copy, mbox, next, pipe, print, Print,
422 top, type, Type, undelete. The delete, dp, and dt commands
423 may also cause the next message to be marked as read, depend‐
424 ing on the value of the autoprint variable. Messages that are
425 in the system mailbox and in state read when mailx quits
426 shall be saved in the mbox, unless the internal variable hold
427 was set. Messages that are in the mbox or in a secondary
428 mailbox and in state read when mailx quits shall be retained
429 in their current location.
430 deleted The message has been processed by one of the following com‐
432 mands: delete, dp, dt. Messages in state deleted when mailx
433 quits shall be deleted. Deleted messages shall be ignored
434 until mailx quits or changes mailboxes or they are specified
435 to the undelete command; for example, the message specifica‐
436 tion /string shall only search the subject lines of messages
437 that have not yet been deleted, unless the command operating
438 on the list of messages is undelete. No deleted message or
439 deleted message header shall be displayed by any mailx com‐
440 mand other than undelete.
441 preserved The message has been processed by a preserve command. When
443 mailx quits, the message shall be retained in its current
444 location.
445 saved The message has been processed by one of the following com‐
447 mands: save or write. If the current mailbox is the system
448 mailbox, and the internal variable keepsave is set, messages
449 in the state saved shall be saved to the file designated by
450 the MBOX variable (see the ENVIRONMENT VARIABLES section). If
451 the current mailbox is the system mailbox, messages in the
452 state saved shall be deleted from the current mailbox, when
453 the quit or file command is used to exit the current mailbox.
454 The header-summary line for each message shall indicate the state of
456 the message.
457 Many commands take an optional list of messages (msglist) on which to
459 operate, which defaults to the current message. A msglist is a list of
460 message specifications separated by <blank> characters, which can
461 include:
462 n Message number n.
464 + The next undeleted message, or the next deleted message for the
466 undelete command.
467 - The next previous undeleted message, or the next previous
469 deleted message for the undelete command.
470 . The current message.
472 ^ The first undeleted message, or the first deleted message for
474 the undelete command.
475 $ The last message.
477 * All messages.
479 n‐m An inclusive range of message numbers.
481 address All messages from address; any address as shown in a header
483 summary shall be matchable in this form.
484 /string All messages with string in the subject line (case ignored).
486 :c All messages of type c, where c shall be one of:
488 d Deleted messages.
490 n New messages.
492 o Old messages (any not in state read or new).
494 r Read messages.
496 u Unread messages.
498 Other commands take an optional message (message) on which to operate,
500 which defaults to the current message. All of the forms allowed for
501 msglist are also allowed for message, but if more than one message is
502 specified, only the first shall be operated on.
503 Other arguments are usually arbitrary strings whose usage depends on
505 the command involved.
506 Start-Up in mailx
508 At start-up time, mailx shall take the following steps in sequence:
509 1. Establish all variables at their stated default values.
511 2. Process command line options, overriding corresponding default val‐
513 ues.
514 3. Import any of the DEAD, EDITOR, MBOX, LISTER, PAGER, SHELL, or VIS‐
516 UAL variables that are present in the environment, overriding the
517 corresponding default values.
518 4. Read mailx commands from an unspecified system start-up file,
520 unless the -n option is given, to initialize any internal mailx
521 variables and aliases.
522 5. Process the user start-up file of mailx commands named in the user
524 MAILRC variable.
525 Most regular mailx commands are valid inside start-up files, the most
527 common use being to set up initial display options and alias lists. The
528 following commands shall be invalid in a start-up file: !, edit, hold,
529 mail, preserve, reply, Reply, shell, visual, Copy, followup, and Fol‐
530 lowup. Any errors in a start-up file shall either cause mailx to ter‐
531 minate with a diagnostic message and a non-zero status or to continue
532 after writing a diagnostic message, ignoring the remainder of the lines
533 in the file.
534 A blank line in a start-up file shall be ignored.
536 Internal Variables in mailx
538 The following variables are internal mailx variables. Each internal
539 variable can be set via the mailx set command at any time. The unset
540 and set no name commands can be used to erase variables.
541 In the following list, variables shown as:
543 variable
546 represent Boolean values. Variables shown as:
548 variable=value
551 shall be assigned string or numeric values. For string values, the
553 rules in Commands in mailx concerning filenames and quoting shall also
554 apply.
555 The defaults specified here may be changed by the unspecified system
557 start-up file unless the user specifies the -n option.
558 allnet All network names whose login name components match shall be
560 treated as identical. This shall cause the msglist message
561 specifications to behave similarly. The default shall be
562 noallnet. See also the alternates command and the metoo
563 variable.
564 append Append messages to the end of the mbox file upon termination
566 instead of placing them at the beginning. The default shall
567 be noappend. This variable shall not affect the save command
568 when saving to mbox.
569 ask, asksub
571 Prompt for a subject line on outgoing mail if one is not
572 specified on the command line with the -s option. The ask and
573 asksub forms are synonyms; the system shall refer to asksub
574 and noasksub in its messages, but shall accept ask and noask
575 as user input to mean asksub and noasksub. It shall not be
576 possible to set both ask and noasksub, or noask and asksub.
577 The default shall be asksub, but no prompting shall be done
578 if standard input is not a terminal.
579 askbcc Prompt for the blind copy list. The default shall be
581 noaskbcc.
582 askcc Prompt for the copy list. The default shall be noaskcc.
584 autoprint Enable automatic writing of messages after delete and
586 undelete commands. The default shall be noautoprint.
587 bang Enable the special-case treatment of <exclamation-mark> char‐
589 acters ('!') in escape command lines; see the escape command
590 and Command Escapes in mailx. The default shall be nobang,
591 disabling the expansion of '!' in the command argument to
592 the ~! command and the ~<!command escape.
593 cmd=command
595 Set the default command to be invoked by the pipe command.
596 The default shall be nocmd.
597 crt=number
599 Pipe messages having more than number lines through the com‐
600 mand specified by the value of the PAGER variable. The
601 default shall be nocrt. If it is set to null, the value used
602 is implementation-defined.
603 debug Enable verbose diagnostics for debugging. Messages are not
605 delivered. The default shall be nodebug.
606 dot When dot is set, a <period> on a line by itself during mes‐
608 sage input from a terminal shall also signify end-of-file (in
609 addition to normal end-of-file). The default shall be nodot.
610 If ignoreeof is set (see below), a setting of nodot shall be
611 ignored and the <period> is the only method to terminate
612 input mode.
613 escape=c Set the command escape character to be the character 'c'. By
615 default, the command escape character shall be <tilde>. If
616 escape is unset, <tilde> shall be used; if it is set to null,
617 command escaping shall be disabled.
618 flipr Reverse the meanings of the R and r commands. The default
620 shall be noflipr.
621 folder=directory
623 The default directory for saving mail files. User-specified
624 filenames beginning with a <plus-sign> ('+') shall be
625 expanded by preceding the filename with this directory name
626 to obtain the real pathname. If directory does not start with
627 a <slash> ('/'), the contents of HOME shall be prefixed to
628 it. The default shall be nofolder. If folder is unset or set
629 to null, user-specified filenames beginning with '+' shall
630 refer to files in the current directory that begin with the
631 literal '+' character. See also outfolder below. The folder
632 value need not affect the processing of the files named in
633 MBOX and DEAD.
634 header Enable writing of the header summary when entering mailx in
636 Receive Mode. The default shall be header.
637 hold Preserve all messages that are read in the system mailbox
639 instead of putting them in the mbox save file. The default
640 shall be nohold.
641 ignore Ignore interrupts while entering messages. The default shall
643 be noignore.
644 ignoreeof Ignore normal end-of-file during message input. Input can be
646 terminated only by entering a <period> ('.') on a line by
647 itself or by the ~. command escape. The default shall be
648 noignoreeof. See also dot above.
649 indentprefix=string
651 A string that shall be added as a prefix to each line that is
652 inserted into the message by the ~m command escape. This
653 variable shall default to one <tab>.
654 keep When a system mailbox, secondary mailbox, or mbox is empty,
656 truncate it to zero length instead of removing it. The
657 default shall be nokeep.
658 keepsave Keep the messages that have been saved from the system mail‐
660 box into other files in the file designated by the variable
661 MBOX, instead of deleting them. The default shall be nokeep‐
662 save.
663 metoo Suppress the deletion of the login name of the user from the
665 recipient list when replying to a message or sending to a
666 group. The default shall be nometoo.
667 onehop When responding to a message that was originally sent to sev‐
669 eral recipients, the other recipient addresses are normally
670 forced to be relative to the originating author's machine for
671 the response. This flag disables alteration of the recipi‐
672 ents' addresses, improving efficiency in a network where all
673 machines can send directly to all other machines (that is,
674 one hop away). The default shall be noonehop.
675 outfolder Cause the files used to record outgoing messages to be
677 located in the directory specified by the folder variable
678 unless the pathname is absolute. The default shall be noout‐
679 folder. See the record variable.
680 page Insert a <form-feed> after each message sent through the pipe
682 created by the pipe command. The default shall be nopage.
683 prompt=string
685 Set the command-mode prompt to string. If string is null or
686 if noprompt is set, no prompting shall occur. The default
687 shall be to prompt with the string "? ".
688 quiet Refrain from writing the opening message and version when
690 entering mailx. The default shall be noquiet.
691 record=file
693 Record all outgoing mail in the file with the pathname file.
694 The default shall be norecord. See also outfolder above.
695 save Enable saving of messages in the dead-letter file on inter‐
697 rupt or delivery error. See the variable DEAD for the loca‐
698 tion of the dead-letter file. The default shall be save.
699 screen=number
701 Set the number of lines in a screenful of headers for the
702 headers and z commands. If screen is not specified, a value
703 based on the terminal type identified by the TERM environment
704 variable, the window size, the baud rate, or some combination
705 of these shall be used.
706 sendwait Wait for the background mailer to finish before returning.
708 The default shall be nosendwait.
709 showto When the sender of the message was the user who is invoking
711 mailx, write the information from the To: line instead of the
712 From: line in the header summary. The default shall be
713 noshowto.
714 sign=string
716 Set the variable inserted into the text of a message when the
717 ~a command escape is given. The default shall be nosign. The
718 character sequences '\t' and '\n' shall be recognized in the
719 variable as <tab> and <newline> characters, respectively.
720 (See also ~i in Command Escapes in mailx.)
721 Sign=string
723 Set the variable inserted into the text of a message when the
724 ~A command escape is given. The default shall be noSign. The
725 character sequences '\t' and '\n' shall be recognized in the
726 variable as <tab> and <newline> characters, respectively.
727 toplines=number
729 Set the number of lines of the message to write with the top
730 command. The default shall be 5.
731 Commands in mailx
733 The following mailx commands shall be provided. In the following list,
734 header refers to lines from the message header, as shown in the OUTPUT
735 FILES section. Header-line refers to lines within the header that
736 begin with one or more non-white-space characters, immediately followed
737 by a <colon> and white space and continuing until the next line begin‐
738 ning with a non-white-space character or an empty line. Header-field
739 refers to the portion of a header line prior to the first <colon> in
740 that line.
741 For each of the commands listed below, the command can be entered as
743 the abbreviation (those characters in the Synopsis command word preced‐
744 ing the '['), the full command (all characters shown for the command
745 word, omitting the '[' and ']'), or any truncation of the full command
746 down to the abbreviation. For example, the exit command (shown as
747 ex[it] in the Synopsis) can be entered as ex, exi, or exit.
748 The arguments to commands can be quoted, using the following methods:
750 * An argument can be enclosed between paired double-quotes ("") or
752 single-quotes (''); any white space, shell word expansion, or
753 <backslash> characters within the quotes shall be treated literally
754 as part of the argument. A double-quote shall be treated literally
755 within single-quotes and vice versa. These special properties of
756 the <quotation-mark> characters shall occur only when they are
757 paired at the beginning and end of the argument.
758 * A <backslash> outside of the enclosing quotes shall be discarded
760 and the following character treated literally as part of the argu‐
761 ment.
762 * An unquoted <backslash> at the end of a command line shall be dis‐
764 carded and the next line shall continue the command.
765 Filenames, where expected, shall be subjected to the following trans‐
767 formations, in sequence:
768 * If the filename begins with an unquoted <plus-sign>, and the folder
770 variable is defined (see the folder variable), the <plus-sign>
771 shall be replaced by the value of the folder variable followed by a
772 <slash>. If the folder variable is unset or is set to null, the
773 filename shall be unchanged.
774 * Shell word expansions shall be applied to the filename (see Section
776 2.6, Word Expansions). If more than a single pathname results from
777 this expansion and the command is expecting one file, the effects
778 are unspecified.
779 Declare Aliases
781 Synopsis:
782 a[lias] [alias [address...]]
784 g[roup] [alias [address...]]
785 Add the given addresses to the alias specified by alias. The names
787 shall be substituted when alias is used as a recipient address speci‐
788 fied by the user in an outgoing message (that is, other recipients
789 addressed indirectly through the reply command shall not be substituted
790 in this manner). Mail address alias substitution shall apply only when
791 the alias string is used as a full address; for example, when hlj is an
792 alias, hlj@posix.com does not trigger the alias substitution. If no
793 arguments are given, write a listing of the current aliases to standard
794 output. If only an alias argument is given, write a listing of the
795 specified alias to standard output. These listings need not reflect the
796 same order of addresses that were entered.
797 Declare Alternatives
799 Synopsis:
800 alt[ernates] name...
802 (See also the metoo variable.) Declare a list of alternative names for
804 the user's login. When responding to a message, these names shall be
805 removed from the list of recipients for the response. The comparison of
806 names shall be in a case-insensitive manner. With no arguments, alter‐
807 nates shall write the current list of alternative names.
808 Change Current Directory
810 Synopsis:
811 cd [directory]
813 ch[dir] [directory]
814 Change directory. If directory is not specified, the contents of HOME
816 shall be used.
817 Copy Messages
819 Synopsis:
820 c[opy] [file]
822 c[opy] [msglist] file
823 C[opy] [msglist]
824 Copy messages to the file named by the pathname file without marking
826 the messages as saved. Otherwise, it shall be equivalent to the save
827 command.
828 In the capitalized form, save the specified messages in a file whose
830 name is derived from the author of the message to be saved, without
831 marking the messages as saved. Otherwise, it shall be equivalent to the
832 Save command.
833 Delete Messages
835 Synopsis:
836 d[elete] [msglist]
838 Mark messages for deletion from the mailbox. The deletions shall not
840 occur until mailx quits (see the quit command) or changes mailboxes
841 (see the folder command). If autoprint is set and there are messages
842 remaining after the delete command, the current message shall be writ‐
843 ten as described for the print command (see the print command); other‐
844 wise, the mailx prompt shall be written.
845 Discard Header Fields
847 Synopsis:
848 di[scard] [header-field...]
850 ig[nore] [header-field...]
851 Suppress the specified header fields when writing messages. Specified
853 header-fields shall be added to the list of suppressed header fields.
854 Examples of header fields to ignore are status and cc. The fields
855 shall be included when the message is saved. The Print and Type com‐
856 mands shall override this command. The comparison of header fields
857 shall be in a case-insensitive manner. If no arguments are specified,
858 write a list of the currently suppressed header fields to standard out‐
859 put; the listing need not reflect the same order of header fields that
860 were entered.
861 If both retain and discard commands are given, discard commands shall
863 be ignored.
864 Delete Messages and Display
866 Synopsis:
867 dp [msglist]
869 dt [msglist]
870 Delete the specified messages as described for the delete command,
872 except that the autoprint variable shall have no effect, and the cur‐
873 rent message shall be written only if it was set to a message after the
874 last message deleted by the command. Otherwise, an informational mes‐
875 sage to the effect that there are no further messages in the mailbox
876 shall be written, followed by the mailx prompt.
877 Echo a String
879 Synopsis:
880 ec[ho] string ...
882 Echo the given strings, equivalent to the shell echo utility.
884 Edit Messages
886 Synopsis:
887 e[dit] [msglist]
889 Edit the given messages. The messages shall be placed in a temporary
891 file and the utility named by the EDITOR variable is invoked to edit
892 each file in sequence. The default EDITOR is unspecified.
893 The edit command does not modify the contents of those messages in the
895 mailbox.
896 Exit
898 Synopsis:
899 ex[it]
901 x[it]
902 Exit from mailx without changing the mailbox. No messages shall be
904 saved in the mbox (see also quit).
905 Change Folder
907 Synopsis:
908 fi[le] [file]
910 fold[er] [file]
911 Quit (see the quit command) from the current file of messages and read
913 in the file named by the pathname file. If no argument is given, the
914 name and status of the current mailbox shall be written.
915 Several unquoted special characters shall be recognized when used as
917 file names, with the following substitutions:
918 % The system mailbox for the invoking user.
920 %user The system mailbox for user.
922 # The previous file.
924 & The current mbox.
926 +file The named file in the folder directory. (See the folder vari‐
928 able.)
929 The default file shall be the current mailbox.
931 Display List of Folders
933 Synopsis:
934 folders
936 Write the names of the files in the directory set by the folder vari‐
938 able. The command specified by the LISTER environment variable shall be
939 used (see the ENVIRONMENT VARIABLES section).
940 Follow Up Specified Messages
942 Synopsis:
943 fo[llowup] [message]
945 F[ollowup] [msglist]
946 In the lowercase form, respond to a message, recording the response in
948 a file whose name is derived from the author of the message. See also
949 the save and copy commands and outfolder.
950 In the capitalized form, respond to the first message in the msglist,
952 sending the message to the author of each message in the msglist. The
953 subject line shall be taken from the first message and the response
954 shall be recorded in a file whose name is derived from the author of
955 the first message. See also the Save and Copy commands and outfolder.
956 Both forms shall override the record variable, if set.
958 Display Header Summary for Specified Messages
960 Synopsis:
961 f[rom] [msglist]
963 Write the header summary for the specified messages.
965 Display Header Summary
967 Synopsis:
968 h[eaders] [message]
970 Write the page of headers that includes the message specified. If the
972 message argument is not specified, the current message shall not
973 change. However, if the message argument is specified, the current
974 message shall become the message that appears at the top of the page of
975 headers that includes the message specified. The screen variable sets
976 the number of headers per page. See also the z command.
977 Help
979 Synopsis:
980 hel[p]
982 ?
983 Write a summary of commands.
985 Hold Messages
987 Synopsis:
988 ho[ld] [msglist]
990 pre[serve] [msglist]
991 Mark the messages in msglist to be retained in the mailbox when mailx
993 terminates. This shall override any commands that might previously have
994 marked the messages to be deleted. During the current invocation of
995 mailx, only the delete, dp, or dt commands shall remove the preserve
996 marking of a message.
997 Execute Commands Conditionally
999 Synopsis:
1000 i[f] s|r
1002 mail-commands
1003 el[se]
1004 mail-commands
1005 en[dif]
1006 Execute commands conditionally, where if s executes the following mail-
1008 commands, up to an else or endif, if the program is in Send Mode, and
1009 if r shall cause the mail-commands to be executed only in Receive Mode.
1010 List Available Commands
1012 Synopsis:
1013 l[ist]
1015 Write a list of all commands available. No explanation shall be given.
1017 Mail a Message
1019 Synopsis:
1020 m[ail] address...
1022 Mail a message to the specified addresses or aliases.
1024 Direct Messages to mbox
1026 Synopsis:
1027 mb[ox] [msglist]
1029 Arrange for the given messages to end up in the mbox save file when
1031 mailx terminates normally. See MBOX. See also the exit and quit com‐
1032 mands.
1033 Process Next Specified Message
1035 Synopsis:
1036 n[ext] [message]
1038 If the current message has not been written (for example, by the print
1040 command) since mailx started or since any other message was the current
1041 message, behave as if the print command was entered. Otherwise, if
1042 there is an undeleted message after the current message, make it the
1043 current message and behave as if the print command was entered. Other‐
1044 wise, an informational message to the effect that there are no further
1045 messages in the mailbox shall be written, followed by the mailx prompt.
1046 Should the current message location be the result of an immediately
1047 preceding hold, mbox, preserve, or touch command, next will act as if
1048 the current message has already been written.
1049 Pipe Message
1051 Synopsis:
1052 pi[pe] [[msglist] command]
1054 | [[msglist] command]
1055 Pipe the messages through the given command by invoking the command
1057 interpreter specified by SHELL with two arguments: -c and command.
1058 (See also sh -c.) The application shall ensure that the command is
1059 given as a single argument. Quoting, described previously, can be used
1060 to accomplish this. If no arguments are given, the current message
1061 shall be piped through the command specified by the value of the cmd
1062 variable. If the page variable is set, a <form-feed> shall be inserted
1063 after each message.
1064 Display Message with Headers
1066 Synopsis:
1067 P[rint] [msglist]
1069 T[ype] [msglist]
1070 Write the specified messages, including all header lines, to standard
1072 output. Override suppression of lines by the discard, ignore, and
1073 retain commands. If crt is set, the messages longer than the number of
1074 lines specified by the crt variable shall be paged through the command
1075 specified by the PAGER environment variable.
1076 Display Message
1078 Synopsis:
1079 p[rint] [msglist]
1081 t[ype] [msglist]
1082 Write the specified messages to standard output. If crt is set, the
1084 messages longer than the number of lines specified by the crt variable
1085 shall be paged through the command specified by the PAGER environment
1086 variable.
1087 Quit
1089 Synopsis:
1090 q[uit]
1092 end-of-file
1093 Terminate mailx, storing messages that were read in mbox (if the cur‐
1095 rent mailbox is the system mailbox and unless hold is set), deleting
1096 messages that have been explicitly saved (unless keepsave is set), dis‐
1097 carding messages that have been deleted, and saving all remaining mes‐
1098 sages in the mailbox.
1099 Reply to a Message List
1101 Synopsis:
1102 R[eply] [msglist]
1104 R[espond] [msglist]
1105 Mail a reply message to the sender of each message in the msglist. The
1107 subject line shall be formed by concatenating Re:<space> (unless it
1108 already begins with that string) and the subject from the first mes‐
1109 sage. If record is set to a filename, the response shall be saved at
1110 the end of that file.
1111 See also the flipr variable.
1113 Reply to a Message
1115 Synopsis:
1116 r[eply] [message]
1118 r[espond] [message]
1119 Mail a reply message to all recipients included in the header of the
1121 message. The subject line shall be formed by concatenating Re:<space>
1122 (unless it already begins with that string) and the subject from the
1123 message. If record is set to a filename, the response shall be saved at
1124 the end of that file.
1125 See also the flipr variable.
1127 Retain Header Fields
1129 Synopsis:
1130 ret[ain] [header-field...]
1132 Retain the specified header fields when writing messages. This command
1134 shall override all discard and ignore commands. The comparison of
1135 header fields shall be in a case-insensitive manner. If no arguments
1136 are specified, write a list of the currently retained header fields to
1137 standard output; the listing need not reflect the same order of header
1138 fields that were entered.
1139 Save Messages
1141 Synopsis:
1142 s[ave] [file]
1144 s[ave] [msglist] file
1145 S[ave] [msglist]
1146 Save the specified messages in the file named by the pathname file, or
1148 the mbox if the file argument is omitted. The file shall be created if
1149 it does not exist; otherwise, the messages shall be appended to the
1150 file. The message shall be put in the state saved, and shall behave as
1151 specified in the description of the saved state when the current mail‐
1152 box is exited by the quit or file command.
1153 In the capitalized form, save the specified messages in a file whose
1155 name is derived from the author of the first message. The name of the
1156 file shall be taken to be the author's name with all network addressing
1157 stripped off. See also the Copy, followup, and Followup commands and
1158 outfolder variable.
1159 Set Variables
1161 Synopsis:
1162 se[t] [name[=[string]] ...] [name=number ...] [noname ...]
1164 Define one or more variables called name. The variable can be given a
1166 null, string, or numeric value. Quoting and <backslash>-escapes can
1167 occur anywhere in string, as described previously, as if the string
1168 portion of the argument were the entire argument. The forms name and
1169 name= shall be equivalent to name="" for variables that take string
1170 values. The set command without arguments shall write a list of all
1171 defined variables and their values. The no name form shall be equiva‐
1172 lent to unset name.
1173 Invoke a Shell
1175 Synopsis:
1176 sh[ell]
1178 Invoke an interactive command interpreter (see also SHELL).
1180 Display Message Size
1182 Synopsis:
1183 si[ze] [msglist]
1185 Write the size in bytes of each of the specified messages.
1187 Read mailx Commands From a File
1189 Synopsis:
1190 so[urce] file
1192 Read and execute commands from the file named by the pathname file and
1194 return to command mode.
1195 Display Beginning of Messages
1197 Synopsis:
1198 to[p] [msglist]
1200 Write the top few lines of each of the specified messages. If the
1202 toplines variable is set, it is taken as the number of lines to write.
1203 The default shall be 5.
1204 Touch Messages
1206 Synopsis:
1207 tou[ch] [msglist]
1209 Touch the specified messages. If any message in msglist is not specifi‐
1211 cally deleted nor saved in a file, it shall be placed in the mbox upon
1212 normal termination. See exit and quit.
1213 Delete Aliases
1215 Synopsis:
1216 una[lias] [alias]...
1218 Delete the specified alias names. If a specified alias does not exist,
1220 the results are unspecified.
1221 Undelete Messages
1223 Synopsis:
1224 u[ndelete] [msglist]
1226 Change the state of the specified messages from deleted to read. If
1228 autoprint is set, the last message of those restored shall be written.
1229 If msglist is not specified, the message shall be selected as follows:
1230 * If there are any deleted messages that follow the current message,
1232 the first of these shall be chosen.
1233 * Otherwise, the last deleted message that also precedes the current
1235 message shall be chosen.
1236 Unset Variables
1238 Synopsis:
1239 uns[et] name...
1241 Cause the specified variables to be erased.
1243 Edit Message with Full-Screen Editor
1245 Synopsis:
1246 v[isual] [msglist]
1248 Edit the given messages with a screen editor. Each message shall be
1250 placed in a temporary file, and the utility named by the VISUAL vari‐
1251 able shall be invoked to edit each file in sequence. The default editor
1252 shall be vi.
1253 The visual command does not modify the contents of those messages in
1255 the mailbox.
1256 Write Messages to a File
1258 Synopsis:
1259 w[rite] [msglist] file
1261 Write the given messages to the file specified by the pathname file,
1263 minus the message header. Otherwise, it shall be equivalent to the save
1264 command.
1265 Scroll Header Display
1267 Synopsis:
1268 z[+|-]
1270 Scroll the header display forward (if '+' is specified or if no option
1272 is specified) or backward (if '-' is specified) one screenful. The num‐
1273 ber of headers written shall be set by the screen variable.
1274 Invoke Shell Command
1276 Synopsis:
1277 !command
1279 Invoke the command interpreter specified by SHELL with two arguments:
1281 -c and command. (See also sh -c.) If the bang variable is set, each
1282 unescaped occurrence of '!' in command shall be replaced with the com‐
1283 mand executed by the previous ! command or ~! command escape.
1284 Null Command
1286 Synopsis:
1287 # comment
1289 This null command (comment) shall be ignored by mailx.
1291 Display Current Message Number
1293 Synopsis:
1294 =
1296 Write the current message number.
1298 Command Escapes in mailx
1300 The following commands can be entered only from input mode, by begin‐
1301 ning a line with the escape character (by default, <tilde> ('~')). See
1302 the escape variable description for changing this special character.
1303 The format for the commands shall be:
1304 <escape-character><command-char><separator>[<arguments>]
1307 where the <separator> can be zero or more <blank> characters.
1309 In the following descriptions, the application shall ensure that the
1311 argument command (but not mailx-command) is a shell command string. Any
1312 string acceptable to the command interpreter specified by the SHELL
1313 variable when it is invoked as SHELL -c command_string shall be valid.
1314 The command can be presented as multiple arguments (that is, quoting is
1315 not required).
1316 Command escapes that are listed with msglist or mailx-command arguments
1318 are invalid in Send Mode and produce unspecified results.
1319 ~! command
1321 Invoke the command interpreter specified by SHELL with two
1322 arguments: -c and command; and then return to input mode. If
1323 the bang variable is set, each unescaped occurrence of '!'
1324 in command shall be replaced with the command executed by the
1325 previous ! command or ~! command escape.
1326 ~. Simulate end-of-file (terminate message input).
1328 ~: mailx-command, ~_ mailx-command
1330 Perform the command-level request.
1331 ~? Write a summary of command escapes.
1333 ~A This shall be equivalent to ~i Sign.
1335 ~a This shall be equivalent to ~i sign.
1337 ~b name...
1339 Add the names to the blind carbon copy (Bcc) list.
1340 ~c name...
1342 Add the names to the carbon copy (Cc) list.
1343 ~d Read in the dead-letter file. See DEAD for a description of
1345 this file.
1346 ~e Invoke the editor, as specified by the EDITOR environment
1348 variable, on the partial message.
1349 ~f [msglist]
1351 Forward the specified messages. The specified messages shall
1352 be inserted into the current message without alteration. This
1353 command escape also shall insert message headers into the
1354 message with field selection affected by the discard, ignore,
1355 and retain commands.
1356 ~F [msglist]
1358 This shall be the equivalent of the ~f command escape, except
1359 that all headers shall be included in the message, regardless
1360 of previous discard, ignore, and retain commands.
1361 ~h If standard input is a terminal, prompt for a Subject line
1363 and the To, Cc, and Bcc lists. Other implementation-defined
1364 headers may also be presented for editing. If the field is
1365 written with an initial value, it can be edited as if it had
1366 just been typed.
1367 ~i string Insert the value of the named variable, followed by a <new‐
1369 line>, into the text of the message. If the string is unset
1370 or null, the message shall not be changed.
1371 ~m [msglist]
1373 Insert the specified messages into the message, prefixing
1374 non-empty lines with the string in the indentprefix variable.
1375 This command escape also shall insert message headers into
1376 the message, with field selection affected by the discard,
1377 ignore, and retain commands.
1378 ~M [msglist]
1380 This shall be the equivalent of the ~m command escape, except
1381 that all headers shall be included in the message, regardless
1382 of previous discard, ignore, and retain commands.
1383 ~p Write the message being entered. If the message is longer
1385 than crt lines (see Internal Variables in mailx), the output
1386 shall be paginated as described for the PAGER variable.
1387 ~q Quit (see the quit command) from input mode by simulating an
1389 interrupt. If the body of the message is not empty, the par‐
1390 tial message shall be saved in the dead-letter file. See DEAD
1391 for a description of this file.
1392 ~r file, ~< file, ~r !command, ~< !command
1394 Read in the file specified by the pathname file. If the
1395 argument begins with an <exclamation-mark> ('!'), the rest of
1396 the string shall be taken as an arbitrary system command; the
1397 command interpreter specified by SHELL shall be invoked with
1398 two arguments: -c and command. The standard output of com‐
1399 mand shall be inserted into the message.
1400 ~s string Set the subject line to string.
1402 ~t name...
1404 Add the given names to the To list.
1405 ~v Invoke the full-screen editor, as specified by the VISUAL
1407 environment variable, on the partial message.
1408 ~w file Write the partial message, without the header, onto the file
1410 named by the pathname file. The file shall be created or the
1411 message shall be appended to it if the file exists.
1412 ~x Exit as with ~q, except the message shall not be saved in the
1414 dead-letter file.
1415 ~| command
1417 Pipe the body of the message through the given command by
1418 invoking the command interpreter specified by SHELL with two
1419 arguments: -c and command. If the command returns a success‐
1420 ful exit status, the standard output of the command shall
1421 replace the message. Otherwise, the message shall remain
1422 unchanged. If the command fails, an error message giving the
1423 exit status shall be written.
1424
1426 When the -e option is specified, the following exit values are
1427 returned:
1428 0 Mail was found.
1430 >0 Mail was not found or an error occurred.
1432 Otherwise, the following exit values are returned:
1434 0 Successful completion; note that this status implies that all
1436 messages were sent, but it gives no assurances that any of them
1437 were actually delivered.
1438 >0 An error occurred.
1440
1442 When in input mode (Receive Mode) or Send Mode:
1443 * If an error is encountered processing an input line beginning with
1445 a <tilde> ('~') character, (see Command Escapes in mailx), a diag‐
1446 nostic message shall be written to standard error, and the message
1447 being composed may be modified, but this condition shall not pre‐
1448 vent the message from being sent.
1449 * Other errors shall prevent the sending of the message.
1451 When in command mode:
1453 * Default.
1455 The following sections are informative.
1457
1459 Delivery of messages to remote systems requires the existence of commu‐
1460 nication paths to such systems. These need not exist.
1461 Input lines are limited to {LINE_MAX} bytes, but mailers between sys‐
1463 tems may impose more severe line-length restrictions. This volume of
1464 POSIX.1‐2017 does not place any restrictions on the length of messages
1465 handled by mailx, and for delivery of local messages the only limita‐
1466 tions should be the normal problems of available disk space for the
1467 target mail file. When sending messages to external machines, applica‐
1468 tions are advised to limit messages to less than 100000 bytes because
1469 some mail gateways impose message-length restrictions.
1470 The format of the system mailbox is intentionally unspecified. Not all
1472 systems implement system mailboxes as flat files, particularly with the
1473 advent of multimedia mail messages. Some system mailboxes may be multi‐
1474 ple files, others records in a database. The internal format of the
1475 messages themselves is specified with the historical format from Ver‐
1476 sion 7, but only after the messages have been saved in some file other
1477 than the system mailbox. This was done so that many historical applica‐
1478 tions expecting text-file mailboxes are not broken.
1479 Some new formats for messages can be expected in the future, probably
1481 including binary data, bit maps, and various multimedia objects. As
1482 described here, mailx is not prohibited from handling such messages,
1483 but it must store them as text files in secondary mailboxes (unless
1484 some extension, such as a variable or command line option, is used to
1485 change the stored format). Its method of doing so is implementation-
1486 defined and might include translating the data into text file-compati‐
1487 ble or readable form or omitting certain portions of the message from
1488 the stored output.
1489 The discard and ignore commands are not inverses of the retain command.
1491 The retain command discards all header-fields except those explicitly
1492 retained. The discard command keeps all header-fields except those
1493 explicitly discarded. If headers exist on the retained header list,
1494 discard and ignore commands are ignored.
1495
1497 None.
1498
1500 The standard developers felt strongly that a method for applications to
1501 send messages to specific users was necessary. The obvious example is a
1502 batch utility, running non-interactively, that wishes to communicate
1503 errors or results to a user. However, the actual format, delivery mech‐
1504 anism, and method of reading the message are clearly beyond the scope
1505 of this volume of POSIX.1‐2017.
1506 The intent of this command is to provide a simple, portable interface
1508 for sending messages non-interactively. It merely defines a ``front-
1509 end'' to the historical mail system. It is suggested that implementa‐
1510 tions explicitly denote the sender and recipient in the body of the
1511 delivered message. Further specification of formats for either the mes‐
1512 sage envelope or the message itself were deliberately not made, as the
1513 industry is in the midst of changing from the current standards to a
1514 more internationalized standard and it is probably incorrect, at this
1515 time, to require either one.
1516 Implementations are encouraged to conform to the various delivery mech‐
1518 anisms described in the CCITT X.400 standards or to the equivalent
1519 Internet standards, described in Internet Request for Comment (RFC)
1520 documents RFC 819, RFC 920, RFC 921, RFC 1123, and RFC 5322 (which suc‐
1521 ceeded RFC 822).
1522 Many historical systems modified each body line that started with From
1524 by prefixing the 'F' with '>'. It is unnecessary, but allowed, to do
1525 that when the string does not follow a blank line because it cannot be
1526 confused with the next header.
1527 The edit and visual commands merely edit the specified messages in a
1529 temporary file. They do not modify the contents of those messages in
1530 the mailbox; such a capability could be added as an extension, such as
1531 by using different command names.
1532 The restriction on a subject line being {LINE_MAX}-10 bytes is based on
1534 the historical format that consumes 10 bytes for Subject: and the
1535 trailing <newline>. Many historical mailers that a message may
1536 encounter on other systems are not able to handle lines that long, how‐
1537 ever.
1538 Like the utilities logger and lp, mailx admittedly is difficult to
1540 test. This was not deemed sufficient justification to exclude this
1541 utility from this volume of POSIX.1‐2017. It is also arguable that it
1542 is, in fact, testable, but that the tests themselves are not portable.
1543 When mailx is being used by an application that wishes to receive the
1545 results as if none of the User Portability Utilities option features
1546 were supported, the DEAD environment variable must be set to /dev/null.
1547 Otherwise, it may be subject to the file creations described in mailx
1548 ASYNCHRONOUS EVENTS. Similarly, if the MAILRC environment variable is
1549 not set to /dev/null, historical versions of mailx and Mail read ini‐
1550 tialization commands from a file before processing begins. Since the
1551 initialization that a user specifies could alter the contents of mes‐
1552 sages an application is trying to send, such applications must set
1553 MAILRC to /dev/null.
1554 The description of LC_TIME uses ``may affect'' because many historical
1556 implementations do not or cannot manipulate the date and time strings
1557 in the incoming mail headers. Some headers found in incoming mail do
1558 not have enough information to determine the timezone in which the mail
1559 originated, and, therefore, mailx cannot convert the date and time
1560 strings into the internal form that then is parsed by routines like
1561 strftime() that can take LC_TIME settings into account. Changing all
1562 these times to a user-specified format is allowed, but not required.
1563 The paginator selected when PAGER is null or unset is partially unspec‐
1565 ified to allow the System V historical practice of using pg as the
1566 default. Bypassing the pagination function, such as by declaring that
1567 cat is the paginator, would not meet with the intended meaning of this
1568 description. However, any ``portable user'' would have to set PAGER
1569 explicitly to get his or her preferred paginator on all systems. The
1570 paginator choice was made partially unspecified, unlike the VISUAL edi‐
1571 tor choice (mandated to be vi) because most historical pagers follow a
1572 common theme of user input, whereas editors differ dramatically.
1573 Options to specify addresses as cc (carbon copy) or bcc (blind carbon
1575 copy) were considered to be format details and were omitted.
1576 A zero exit status implies that all messages were sent, but it gives no
1578 assurances that any of them were actually delivered. The reliability
1579 of the delivery mechanism is unspecified and is an appropriate market‐
1580 ing distinction between systems.
1581 In order to conform to the Utility Syntax Guidelines, a solution was
1583 required to the optional file option-argument to -f. By making file an
1584 operand, the guidelines are satisfied and users remain portable. How‐
1585 ever, it does force implementations to support usage such as:
1586 mailx -fin mymail.box
1589 The no name method of unsetting variables is not present in all histor‐
1591 ical systems, but it is in System V and provides a logical set of com‐
1592 mands corresponding to the format of the display of options from the
1593 mailx set command without arguments.
1594 The ask and asksub variables are the names selected by BSD and System
1596 V, respectively, for the same feature. They are synonyms in this volume
1597 of POSIX.1‐2017.
1598 The mailx echo command was not documented in the BSD version and has
1600 been omitted here because it is not obviously useful for interactive
1601 users.
1602 The default prompt on the System V mailx is a <question-mark>, on BSD
1604 Mail an <ampersand>. Since this volume of POSIX.1‐2017 chose the mailx
1605 name, it kept the System V default, assuming that BSD users would not
1606 have difficulty with this minor incompatibility (that they can over‐
1607 ride).
1608 The meanings of r and R are reversed between System V mailx and SunOS
1610 Mail. Once again, since this volume of POSIX.1‐2017 chose the mailx
1611 name, it kept the System V default, but allows the SunOS user to
1612 achieve the desired results using flipr, an internal variable in System
1613 V mailx, although it has not been documented in the SVID.
1614 The indentprefix variable, the retain and unalias commands, and the ~F
1616 and ~M command escapes were adopted from 4.3 BSD Mail.
1617 The version command was not included because no sufficiently general
1619 specification of the version information could be devised that would
1620 still be useful to a portable user. This command name should be used by
1621 suppliers who wish to provide version information about the mailx com‐
1622 mand.
1623 The ``implementation-specific (unspecified) system start-up file'' his‐
1625 torically has been named /etc/mailx.rc, but this specific name and
1626 location are not required.
1627 The intent of the wording for the next command is that if any command
1629 has already displayed the current message it should display a following
1630 message, but, otherwise, it should display the current message. Con‐
1631 sider the command sequence:
1632 next 3
1635 delete 3
1636 next
1637 where the autoprint option was not set. The normative text specifies
1639 that the second next command should display a message following the
1640 third message, because even though the current message has not been
1641 displayed since it was set by the delete command, it has been displayed
1642 since the current message was anything other than message number 3.
1643 This does not always match historical practice in some implementations,
1644 where the command file address followed by next (or the default com‐
1645 mand) would skip the message for which the user had searched.
1646
1648 None.
1649
1651 Chapter 2, Shell Command Language, ed, ls, more, vi
1652 The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment
1654 Variables, Section 12.2, Utility Syntax Guidelines
1655
1657 Portions of this text are reprinted and reproduced in electronic form
1658 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
1659 table Operating System Interface (POSIX), The Open Group Base Specifi‐
1660 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
1661 Electrical and Electronics Engineers, Inc and The Open Group. In the
1662 event of any discrepancy between this version and the original IEEE and
1663 The Open Group Standard, the original IEEE and The Open Group Standard
1664 is the referee document. The original Standard can be obtained online
1665 at http://www.opengroup.org/unix/online.html .
1666 Any typographical or formatting errors that appear in this page are
1668 most likely to have been introduced during the conversion of the source
1669 files to man page format. To report such errors, see https://www.ker‐
1670 nel.org/doc/man-pages/reporting_bugs.html .
1671IEEE/The Open Group 2017 MAILX(1P)