mailx.html

unix 下的C开发手册,还用详细的例程。

empty line</i><b>]
<br>
[</b><i>line beginning with </i>From&lt;space&gt;...<b>]</b>
</dl>
</p>
where each message begins with the
<b>From</b> &lt;space&gt;
line shown, preceded by the beginning of the file or an empty line.
(The
<b>From</b> &lt;space&gt;
line is considered to be part of the message header,
but not one of the header-lines referred to in
<xref href=mxcmds><a href="#tag_001_014_1358_003">
Commands in mailx
</a></xref>;
thus, it is not affected by the
<b>discard</b>,
<b>ignore</b>
or
<b>retain</b>
commands.)
The formats of the remainder of the
<b>From</b> &lt;space&gt;
line and any additional header lines are unspecified,
except that none will be empty.
The format of a message body line is also unspecified,
except that no line following an empty line can start with
<b>From</b> &lt;space&gt;;
<i>mailx</i>
will modify any such user-entered message body lines
(following an empty line and beginning with
<b>From</b> &lt;space&gt;)
by adding one or more characters to precede the
F;
it may add these characters to
<b>From</b> &lt;space&gt;
lines that are not preceded by an empty line.
<p>
When a message from the system mailbox or entered by the
user is not a text file, it is implementation-dependent how
such a message is stored in files written by
<i>mailx</i>.
</blockquote><h4><a name = "tag_001_014_1358">&nbsp;</a>EXTENDED DESCRIPTION</h4><blockquote>
The
<i>mailx</i>
utility cannot guarantee support for all character encodings
in all circumstances.
For example,
inter-system mail may be restricted to 7-bit data by the underlying
network, 8-bit data need not be portable to non-internationalised
systems, and so on.
Under these circumstances, it is recommended that
only characters defined in the
ISO/IEC&nbsp;646:1991 standard International Reference Version
(equivalent to ASCII) 7-bit range of
characters be used.
<p>
When
<i>mailx</i>
is invoked using one of the Receive Mode synopsis forms,
it will write
the page of header-summary lines (see below) containing the first new
message (if
<b>-N</b>
is not specified),
or the first unread message if there are no new messages, or
the first message if there are no new or unread messages,
followed by a prompt indicating
<i>mailx</i>
can accept regular commands
(see
<xref href=mxcmds><a href="#tag_001_014_1358_003">
Commands in mailx
</a></xref>);
this is termed
<i>command mode</i>.
When
<i>mailx</i>
is invoked using the Send Mode synopsis
and standard input is a terminal,
if no subject is specified on the command line and the
<b>asksub</b>
variable is set,
a prompt for the subject will be written.
At this point
<i>mailx</i>
is in
<i>input mode</i>.
This input mode is also entered when using one of the Receive Mode
synopsis forms and a reply or new message is composed using the
<b>reply</b>,
<b>Reply</b>,
<b>followup</b>,
<b>Followup</b>
or
<b>mail</b>
commands.
When the message is typed and the end of message is encountered, the
message will be passed to the mail delivery software.
Commands can be entered by beginning a line with the
escape character (by default, tilde
(^))
followed by a single command letter and optional arguments.
See
<xref href=mxcmdesc><a href="#tag_001_014_1358_049">
Command Escapes in mailx
</a></xref>
for a summary of these commands.
<dl><dt><b>Note:</b>
<dd>For notational convenience, this section uses
the default escape character, tilde, in all
references and examples.
</dl>
<p>
At any time,
the behaviour of
<i>mailx</i>
is governed by a set of environmental
and internal variables.
These are flags and valued parameters that
can be set and cleared via the
<i>mailx</i>
<b>set</b>
and
<b>unset</b>
commands.
<p>
Regular commands are of the form:
<p><code>
<b>[</b><i>command</i><b>]</b>
<b>[</b><i>msglist</i><b>]</b>
<b>[</b><i>argument&nbsp;...</i><b>]</b>
</code>
<p>
If no
<i>command</i>
is specified in command mode,
<b>print</b>
is assumed.
In input mode,
commands are recognised by the escape character,
and lines not treated as commands are taken as input for the message.
<p>
In command mode,
each message will be assigned a sequential number,
starting with 1.
<p>
All messages have a state that affects how they
are displayed in the header summary and how
they are retained or deleted upon termination of
<i>mailx</i>.
There is at any time the notion of a
<i>current</i>
message, marked by a
"&gt;"
at the beginning of a line in the header summary.
All messages are in one of the following states:
<dl compact>

<dt><i>new</i><dd>The message is present in the system mailbox and has
not been viewed by the user or moved to any other state.
Messages in state
<i>new</i>
when
<i>mailx</i>
quits will be retained in the system mailbox.

<dt><i>unread</i><dd>The message has been present in the system mailbox for more
than one invocation of
<i>mailx</i>
and has not been viewed by the user or moved to any other state.
Messages in state
<i>unread</i>
when
<i>mailx</i>
quits will be retained in the system mailbox.


<dt><i>read</i><dd>The message has been processed by one of the following commands:
<b>~f</b>,
<b>~m</b>,
<b>~F</b>,
<b>~M</b>,
<b>copy</b>,
<b>mbox</b>,
<b>next</b>,
<b>pipe</b>,
<b>print</b>,
<b>Print</b>,
<b>top</b>,
<b>type</b>,
<b>Type</b>,
<b>undelete</b>.
The
<b>delete</b>,
<b>dp</b>
and
<b>dt</b>
commands may also cause the next message to be marked as
<i>read</i>,
depending on the value of the
<b>autoprint</b>
variable.
Messages that are in the system mailbox and in state
<i>read</i>
when
<i>mailx</i>
quits will be saved in the
<b>mbox</b>
unless the internal variable
<b>hold</b>
was set.
Messages that are in the
<b>mbox</b>
or in a secondary mailbox and in state
<i>read</i>
when
<i>mailx</i>
quits will be retained in their current location.

<dt><i>deleted</i><dd>The message has been processed by one of the following commands:
<b>delete</b>,
<b>dp</b>,
<b>dt</b>.
A message processed by
<b>save</b>
will be in state
<i>deleted</i>
unless the internal variable
<b>keepsave</b>
was set.
Messages in state
<i>deleted</i>
when
<i>mailx</i>
quits will be deleted.

<dt><i>preserved</i><dd>
The message has been processed by a
<b>preserve</b>
command.
When
<i>mailx</i>
quits, the message will be retained in its current location.

</dl>
<p>
The header-summary line for each message will indicate
the state of the message.
<p>
Many commands take an optional list of messages
(<i>msglist</i>)
on which to operate, which defaults to the current message.
A
<i>msglist</i>
is a list of message specifications separated by
blank characters,
which can include:
<dl compact>

<dt><i>n</i><dd>Message number
<i>n</i>.

<dt><b>+</b><dd>The next undeleted message, or the next deleted message for the
<b>undelete</b>
command.

<dt><b>-</b><dd>The next previous undeleted message,
or the next previous deleted message for the
<b>undelete</b>
command.

<dt><b>.</b><dd>The current message.

<dt><b>^</b><dd>The first undeleted message,
or the first deleted message for the
<b>undelete</b>
command.

<dt><b>$</b><dd>The last message.

<dt><b>*</b><dd>All messages.

<dt><i>n</i><b>-</b><i>m</i><dd>An inclusive range of message numbers.

<dt><i>address</i><dd>All messages from
<i>address</i>;
any address as shown in a header summary will be matchable in this form.

<dt><b>/</b><i>string</i><dd>All messages with
<i>string</i>
in the subject line (case ignored).

<dt><b>:</b><i>c</i><dd>All messages of type
<i>c</i>,
where
<i>c</i>
must be one of:
<dl compact>

<dt><b>d</b><dd>deleted messages

<dt><b>n</b><dd>new messages

<dt><b>o</b><dd>old messages (any not in state
<i>read</i>
or
<i>new</i>)

<dt><b>r</b><dd>read messages

<dt><b>u</b><dd>unread messages

</dl>
<p>
</dl>
<p>
Other commands take an optional message
(<i>message</i>)
on which to operate,
which defaults to the current message.
All of the forms allowed for
<i>msglist</i>
are also allowed for
<i>message</i>,
but if more than one
message is specified, only the first will be operated on.
<p>
Other arguments are usually arbitrary strings whose usage
depends on the command involved.
<h5><a name = "tag_001_014_1358_001">&nbsp;</a>Start-up in mailx</h5>
At start-up time,
<i>mailx</i>
will take the following steps in sequence:
<ol>
<p>
<li>
Establish all variables at their stated default values.
<p>
<li>
Process command-line options,
overriding corresponding default values.
<p>
<li>
Import any of the
<i>DEAD ,
</i><i>EDITOR ,
</i><i>MBOX ,
</i><i>LISTER ,
</i><i>PAGER ,
</i><i>SHELL</i>
or
<i>VISUAL</i>
variables that are present in the environment,
overriding the corresponding default values.
<p>
<li>
Read
<i>mailx</i>
commands from an unspecified system start-up file, unless the
<b>-n</b>
option is given,
to initialise any internal
<i>mailx</i>
variables and aliases.
<p>
<li>
Process the start-up file of
<i>mailx</i>
commands named in the user
<i>MAILRC</i>
variable.
<p>
</ol>
<p>
Most regular
<i>mailx</i>
commands are valid inside start-up files,
the most common use being to set up initial display options and alias lists.
The following commands are invalid in the start-up file:
<b>!</b>,
<b>edit</b>,
<b>hold</b>,
<b>mail</b>,
<b>preserve</b>,
<b>reply</b>,
<b>Reply</b>,
<b>shell</b>,
<b>visual</b>,
<b>Copy</b>,
<b>followup</b>
and
<b>Followup</b>.
Any errors in the start-up file will either cause
<i>mailx</i>
to terminate with a diagnostic message and
a non-zero status or to continue after writing a diagnostic message,
ignoring the remainder of the lines in the start-up file.
<p>
A blank line in a start-up file is ignored.
<h5><a name = "tag_001_014_1358_002">&nbsp;</a>Internal Variables in mailx</h5>
<xref type="5" name="mxintv"></xref>
The following variables are internal
<i>mailx</i>
variables.
Each internal variable
can be set via the
<i>mailx</i>
<b>set</b>
command at any time.
The
<b>unset</b>
and
<b>set&nbsp;no</b><i>name</i>
commands can be used to erase variables.
<p>
In the following list, variables shown as:
<pre>
<code>
variable
</code>
</pre>
represent Boolean values.
Variables shown as:
<pre>
<code>
variable=<i>value</i>
</code>
</pre>
will be assigned string or numeric values.
For string values, the rules in
<xref href=mxcmds><a href="#tag_001_014_1358_003">
Commands in mailx
</a></xref>
concerning filenames and quoting also apply.
<p>
The defaults specified here may be changed by the implementation-dependent
system start-up file unless the user specifies the
<b>-n</b>
option.
<dl compact>

<dt><b>allnet</b><dd>All network names whose login name components match are treated as
identical.
This causes the
<i>msglist</i>
message specifications to behave similarly.
The default is
<b>noallnet</b>.
See also the
<b>alternates</b>
command and the
<b>metoo</b>
variable.

<dt><b>append</b><dd>Append messages to the end of the
<b>mbox</b>
file upon termination instead of placing them
at the beginning.
The default is
<b>noappend</b>.
This variable will not affect the
<b>save</b>
command when saving to the
<b>mbox</b>.


<dt><b>ask</b><dd>
<dt><b>asksub</b><dd>Prompt for a subject line
on outgoing mail if one is not specified on the command line
with the
<b>-s</b>
option.
The
<b>ask</b>
and
<b>asksub</b>
forms are synonyms;
the system will refer to
<b>asksub</b>
and
<b>noasksub</b>
in its messages, but will accept
<b>ask</b>
and
<b>noask</b>
as user input to mean
<b>asksub</b>
and
<b>noasksub</b>.
It is not possible to set both
<b>ask</b>
and
<b>noasksub</b>,
or
<b>noask</b>
and
<b>asksub</b>.
The default is
<b>asksub</b>,
but no prompting will be done if standard input
is not a terminal.

<dt><b>askbcc</b><dd>Prompt for the blind copy list.
The default is
<b>noaskbcc</b>.

<dt><b>askcc</b><dd>Prompt for the copy list.