ch14.htm

linux-unix130.linux.and.unix.ebooks130 linux and unix ebookslinuxLearning Linux - Collection of 12 E

<P>You can answer Calvin by initiating another <TT>write</TT> session from your end

and typing your message. You have to press Enter at the end of each line for it to

be displayed at the other terminal. To simplify communications, you can type <TT>over</TT>

at the logical end of your sentence. Calvin should do likewise.

<H4 ALIGN="CENTER"><A NAME="Heading8<FONT COLOR="#000077">write Etiquette</FONT></H4>

<P>If you are waiting for the other party to respond to your <TT>write</TT> request,

it is polite to let him reply while you wait. Only after he has accepted your invitation

should the conversation begin. Also, let the called party have the first chance to

reply by typing <TT>hello</TT> or any other salutation. Avoid typing until the other

party stops or signals you to begin with an end-of-message word, such as <TT>over</TT>.

Remember, only one person can speak at a time on this channel.

<H3 ALIGN="CENTER"><A NAME="Heading9<FONT COLOR="#000077">The talk Communication

Tool</FONT></H3>

<P>The <TT>write</TT> tool was nice for communicating one at a time. However, UNIX

enables you to type simultaneously with the <TT>talk</TT> tool.</P>

<P><TT>talk</TT> is an interactive communication tool that enables you to have an

actual conversation in real-time mode with another user. You can actually see the

conversation being typed as the other user is typing it. For <TT>talk</TT> to work,

the other user has to be logged in, just as in <TT>write</TT>.</P>

<P><TT>talk</TT> can be very annoying and disturbing if someone wants to be pesky.

If you don't want to be disturbed, just turn <TT>talk</TT> off by entering <TT>mesg

n</TT> at the prompt.

<H4 ALIGN="CENTER"><A NAME="Heading10<FONT COLOR="#000077">A Sample talk Session</FONT></H4>

<P>You can talk to somebody by typing <TT>talk</TT> followed by the user's login

ID. To see if the user is logged in, you can use the <TT>who</TT> command just like

you did for <TT>write</TT>. Let's try to talk to Calvin:<FONT COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">$  talk calvin

</FONT></PRE>

<P>The computer responds with<FONT COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">[Waiting for your party to respond]

</FONT></PRE>

<P>The user on the other end sees the following message even if he is in the middle

of an edit session. The system beeps and displays the following message on the terminal:<FONT

COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">Message from Talk_Daemon@mpsi at 13:08 ...

talk: connection requested by [e-mail].

talk: respond with:  talk [e-mail]

</FONT></PRE>

<P>To respond to this phone call, type the command shown in the <TT>respond with</TT>

message shown here. If your friend does not respond, the <TT>talk</TT> daemon persistently

bothers him with the preceding message every 30 seconds.</P>

<P>At your terminal, you see the following messages:<FONT COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">[Ringing your party again]

[Ringing your party again]

[Ringing your party again]

[Ringing your party again]

</FONT></PRE>

<P>Occasionally, you will see the following message:<FONT COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">[Your party is refusing messages]

</FONT></PRE>

<P>What happened? Your friend at the other end does not want to talk or be disturbed.

After several of your interruptions, he has decided to turn his <TT>mesg</TT> off.

That is why you got the message that your party is refusing messages.</P>

<P>Now let's look at a nicer scenario, when someone wants to talk to you. He has

to respond with the following command:<FONT COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">talk laurel

</FONT></PRE>

<P>Then your terminal displays the following screen:</P>

<P>[Connection Established]</P>

<P>---------------------------------------</P>

<P>The screen is divided horizontally with a dotted line, and you can type your message

on the top half of the screen. This appears verbatim on the other terminal at the

bottom half of the screen. You can type your messages, and the other user can type

his, simultaneously.</P>

<P>The connection can be closed by entering Ctrl-C. The following line appears on

the screen:<FONT COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">[Connection closing.Exiting]

</FONT></PRE>

<P>You should now be back at your shell's command prompt.

<H4 ALIGN="CENTER"><A NAME="Heading11<FONT COLOR="#000077">talk Etiquette</FONT></H4>

<P>The same etiquette applies to <TT>talk</TT> as in <TT>write</TT>. Always use lowercase

letters, because CAPS LOCK conversations are considered loud and rude. Always finish

your sentence by typing <TT>over</TT>. If you initiated the talk session, wait for

the other party to respond with the <TT>hello</TT> first. To prevent both of you

from typing at the same time, always read your message, wait for the <TT>over</TT>,

type your own message, and then terminate it with <TT>over</TT>.

<H3 ALIGN="CENTER"><A NAME="Heading12<FONT COLOR="#000077">Electronic Mail</FONT></H3>

<P>Electronic mail has taken the world by storm. E-mail, short for electronic mail,

is a method of sending a message from a user on one computer to one or several recipients

on another computer. E-mail provides fast and efficient transportation of data and

documents. This mode of communication also eliminates the need to play telephone

tag or to wait for a convenient or appropriate time to call someone. For someone

with Internet access, e-mail provides the means to communicate with friends around

the world.

<H4 ALIGN="CENTER"><A NAME="Heading13<FONT COLOR="#000077">Mailboxes and Agents</FONT></H4>

<P>E-mail is stored in a file called the system mail in the mailbox. System mail

has the same name as that of the user. For example, a user named Calvin will have

a mailbox under Linux in <TT>/var/spool/mail/calvin</TT>.</P>

<P>E-mail originates in the form of a file on your computer created by a Mail User

Agent (MUA). E-mail is then submitted to a mail router such as sendmail, after which

it is handed over to a Mail Transporter Agent (MTA). E-mail is then appended to a

mailbox. The MTA delivers it to the final delivery agent by traversing one or more

hosts.</P>

<P>The MUA is used to read and send mail. The MUA is the user interface for the mail

system. Mail can be composed by using simple MUAs such as mail or mailx, or sophisticated

mail user agents such as <TT>elm</TT> or pine.

<H4 ALIGN="CENTER"><A NAME="Heading14<FONT COLOR="#000077">Understanding the

Mail Message</FONT></H4>

<P>A mail message includes two parts: a mail header and the text body.</P>

<P>The mail header is generated by the mail program automatically. A typical header

in a mail message looks like this:<FONT COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">Date: Fri, 6 Jan 1995 13:27:00 -0600

From: &quot;Calvin N. Hobbes&quot; &lt;[e-mail]&gt;

To: [e-mail]

Subject: Format for a mail header

Hi, just checking the different parts in a mail message

</FONT></PRE>

<P><TT>Date</TT> specifies the date and time the message is sent.</P>

<P><TT>From</TT> specifies both the sender's name in quotes and the address, which

includes the login ID and the address of their machine, <TT>hobbes.com</TT>.</P>

<P><TT>To</TT> is the recipient's mail address.</P>

<P><TT>Subject</TT> is a one-line description of the mail message.</P>

<P>The mail header is followed by the body of the mail message. Here you type the

message as text. The mail message is terminated by typing a period (<TT>.</TT>) as

the first character on the last line. The mail handler responds with <TT>EOT</TT>,

for End Of Text. This is the standard procedure for Berkeley Mail; other mail handlers

have their own way of ending message text entry.

<H4 ALIGN="CENTER"><A NAME="Heading15<FONT COLOR="#000077">Types of Mail User

Agents</FONT></H4>

<P>There are several types of mail user agents, some of which are listed here. A

variety of different programs can be used for reading the mail. The two most common

programs are <TT>mail</TT> and <TT>Mail</TT> (also called <TT>mailx</TT>). Because

of the similarity of their names, <TT>Mail</TT> is also called <TT>capmail</TT> or

Berkeley Mail. Berkeley Mail is far superior to <TT>mail</TT> because it is much

easier to use.</P>

<P>This section covers the following types of mail user agents:



<UL>

	<LI><TT>elm</TT>

	<P>

	<LI>Pine

	<P>

	<LI><TT>mailx</TT> (Berkeley Mail)

</UL>



<P>Using elm <TT>elm</TT>, which stands for electronic mail, provides a full-screen

interface mail program with a good help feature. <TT>elm</TT> is a pleasure to use

when compared with Berkeley Mail because of its simplicity of use and functionality.</P>

<P>Start the <TT>elm</TT> system by typing <TT>elm</TT> at the command prompt:<FONT

COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">$ elm

</FONT></PRE>

<P>The screen is cleared, and the code shown in Listing 14.1 is displayed.

<H3 ALIGN="CENTER"><A NAME="Heading16<FONT COLOR="#000077">Listing 14.1. elms

main screen.</FONT><FONT COLOR="#0066FF"></FONT></H3>

<PRE><FONT COLOR="#0066FF">$ elm

  Mailbox is `/var/spool/mail/calvin' with 5 messages [ELM 2.4 PL25]



  N  1   Jan 12 Laurel N. Hardy     (15)   using el

  N  2   Jan 12 Laurel N. Hardy     (15)   2nd elm message

  N  3   Jan 12 Laurel N. Hardy     (16)   Using elm

  N  4   Jan 11 Laurel N. Hardy     (11)   Re: Format for a mail header

  N  5   Jan 11 Laurel N. Hardy     (11)   message # 1

    You can use any of the following commands by pressing the first character;

</FONT></PRE>

<P>d)elete or u)ndelete mail, m)ail a message, r)eply or f)orward mail, q)uit</P>

<P>To read a message, press &lt;return&gt;. j = move down, k = move up, ? = help<FONT

COLOR="#0066FF"></FONT>

<PRE><FONT COLOR="#0066FF">Command:

</FONT></PRE>

<P>The top line on the screen is the mailbox and the number of messages it has in

it. You may also see <TT>elm</TT>'s version number. This is followed by a list of

all the messages in the mailbox, the date the messages were sent, the sender's name,

and the subject of the message.</P>

<P>The current message is indicated by an arrow or inverse video.</P>

<P>One nice feature of <TT>elm</TT> is that it displays the sender's name instead

of the login ID, as Berkeley Mail does.</P>

<P>The bottom part of the screen lists the options available. At this point, you

can reply to the message, delete or undelete a message, or forward the mail by entering

the appropriate command. You can go up and down the message list by using k and j,

just as in the <TT>vi</TT> editor.</P>



<P>Some of the actions available in <TT>elm</TT> are listed in Table 14.1. <BR>

<FONT SIZE="4"></FONT>

<CENTER>

<P><FONT SIZE="4"><B>Table 14.1. elm actions. </B></FONT>

<TABLE BORDER="0">

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT"><I>Command </I></TD>

		<TD ALIGN="LEFT"><I>elm 2.4 Action </I></TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">Enter, Spacebar </TD>

		<TD ALIGN="LEFT">Displays current message. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">| </TD>

		<TD ALIGN="LEFT">Pipes current message or tagged messages to a system command. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">! </TD>

		<TD ALIGN="LEFT">Shell escape. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">? </TD>

		<TD ALIGN="LEFT">This screen of information. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">= </TD>

		<TD ALIGN="LEFT">Sets current message to first message. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">* </TD>

		<TD ALIGN="LEFT">Sets current message to last message. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">&lt;NUMBER&gt;, Enter </TD>

		<TD ALIGN="LEFT">Sets current message to &lt;NUMBER&gt;. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">/ </TD>

		<TD ALIGN="LEFT">Searches From/Subjects for pattern. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">// </TD>

		<TD ALIGN="LEFT">Searches entire message texts for pattern. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">&gt; </TD>

		<TD ALIGN="LEFT">Saves current message or tagged messages to a folder. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">&lt; </TD>

		<TD ALIGN="LEFT">Scans current message for calendar entries. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">C </TD>

		<TD ALIGN="LEFT">Copies current message or tagged messages. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">c </TD>

		<TD ALIGN="LEFT">Changes to another folder. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">d </TD>

		<TD ALIGN="LEFT">Deletes current message. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">Ctrl-D </TD>

		<TD ALIGN="LEFT">Deletes messages with a specified pattern. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">e </TD>

		<TD ALIGN="LEFT">Edits current folder. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">f </TD>

		<TD ALIGN="LEFT">Forwards current message. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">g </TD>

		<TD ALIGN="LEFT">Groups (all recipients') reply to current message. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">h </TD>

		<TD ALIGN="LEFT">Headers displayed with message. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">J </TD>

		<TD ALIGN="LEFT">Increments current message by one. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">j, &lt;DOWN&gt; </TD>

		<TD ALIGN="LEFT">Advances to next undeleted message. </TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">K </TD>

		<TD ALIGN="LEFT">Decrements current message by one. </TD>

	</TR>