WhyCan Forum(哇酷开发者社区)

ds and backwards, or simply enter a message number to
     move directly.

   Disposing of mail
     After examining a message you can delete (d) or reply (r) to it.  Deletion causes the mail
     program to forget about the message.  This is not irreversible; the message can be undeleted
     (u) by giving its number, or the mail session can be aborted by giving the exit (x) command.
     Deleted messages, however, will usually disappear, never to be seen again.

   Specifying messages
     Commands such as print and delete can be given a list of message numbers as arguments to
     apply to a number of messages at once.  Thus delete 1 2 deletes messages 1 and 2, while
     delete 1-5 deletes messages 1 through 5.

     Messages may also be selected using one of the following categories:

           *       all messages
           $       last message
           :d      deleted messages
           :n      new messages
           :o      old messages
           :r      read messages
           :u      unread messages

     Thus the command top, which prints the first few lines of a message, could be used in top *
     to print the first few lines of all messages.

   Replying to or originating mail
     You can use the reply command to set up a response to a message, sending it back to the
     person who it was from.  Text you then type in, up to an end-of-file, defines the contents
     of the message.  While you are composing a message, mail treats lines beginning with the
     tilde (‘~’) character specially.  For instance, typing ~m (alone on a line) will place a
     copy of the current message into the response, right shifting it by a single tab-stop (see
     the indentprefix variable, below).  Other escapes will set up subject fields, add and delete
     recipients to the message, and allow you to escape to an editor to revise the message or to
     a shell to run some commands.  (These options are given in the summary below.)

   Ending a mail processing session
     You can end a mail session with the quit (q) command.  Messages which have been examined go
     to your mbox file unless they have been deleted, in which case they are discarded.
     Unexamined messages go back to the post office (see the -f option above).

   Personal and system wide distribution lists
     It is also possible to create personal distribution lists so that, for instance, you can
     send mail to “cohorts” and have it go to a group of people.  Such lists can be defined by
     placing a line like

           alias cohorts bill ozalp jkf mark kridle@ucbcory

     in the file .mailrc in your home directory.  The current list of such aliases can be
     displayed with the alias command in mail.  System wide distribution lists can be created by
     editing /etc/aliases, (see aliases(5)); these are kept in a different syntax.  In mail you
     send, personal aliases will be expanded in mail sent to others so that they will be able to
     reply to the recipients.  System wide aliases are not expanded when the mail is sent, but
     any reply returned to the machine will have the system wide alias expanded as all mail goes
     through an MTA.

   Recipient address specifications
     Recipient addresses (any of the “To”, “Cc” or “Bcc” header fields) are subject to expansion
     when the expandaddr option is set.

     An address may be expanded as follows:

     ·       An address that starts with a pipe (‘|’) character is treated as a command to run.
             The command immediately following the ‘|’ is executed with the message as its
             standard input.

     ·       An address that starts with a ‘+’ character is treated as a folder.

     ·       An address that contains a ‘/’ character but no ‘!’, ‘%’, or ‘@’ characters is also
             treated as a folder.

     ·       If none of the above apply, the recipient is treated as a local or network mail
             address.

     If the expandaddr option is not set (the default), no expansion is performed and the
     recipient is treated as a local or network mail address.

   Character sets and MIME
     Generally mail does not handle neither different character sets nor any other MIME feature.
     Especially it does not perform any any conversions between character sets while displaying
     or sending mails.

     Starting from April 2017, however, as a Debian extension this version of mail adds a few
     MIME headers to every outgoing mail in order to indicate that the mail is sent as 8-bit
     plain text data that uses character set encoding detected from the current locale(7)
     settings.  The -a command-line option can be used to override those headers, for example:
           $ mail -a 'Content-Type: text/plain; charset="ISO-8859-1"'
     sets header indicating legacy character encoding.

   Network mail (ARPA, UUCP, Berknet)
     See mailaddr(7) for a description of network addresses.

     mail has a number of options which can be set in the .mailrc file to alter its behavior;
     thus set askcc enables the askcc feature.  (These options are summarized below.)