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参考例
If any of these match, they are assigned to the symbol $n for replacement on the right-hand side, where n is the index in the LHS. For example, if the LHS: (LHS Left-Hand Side) $-:$+ is applied to the input UCBARPA:eric the rule will match, and the values passed to the RHS will be $1 UCBARPA $2 eric Additionally, the LHS can include $@ to match zero tokens. This not bound to a $N on the RHS, and is normally only used when it stands alone in order to match the null input.
H?M?Message-Id: <$t.$i@$j>
The address must be composed of pieces of information that uniquely identify the mail message worldwide. We create that address in a way that is commonly used in most configuration files: <$t.$i@$j> $t is the current date and time represented by an integer. $i is the local unique identifier for the queue file for this message (even if the message isn't queued), and $j is your host's fully qualified domain name. Other information may be used, provided that the result looks like a legal address and provided that no two identical identifiers ever go out.
ttp://www.unix.org.ua/orelly/networking/sendmail/ch23_02.htm#SML2-CH-23-SECT-2-1 23.2.1 The Queue Identifier To ensure that new filenames are not the same as the names of files that may already be in the queue, sendmail uses the following pattern for each new ident: AApid prior to V8.6 hourAApid beginning with V8.6 Here, pid is the process identification number of the incarnation of sendmail that is trying to create the file. Because sendmail often fork(2)'s to process the queue, that pid is likely to be unique, resulting in a unique ident. For V8 sendmail an extra letter prefixes the AA. Shown as hour, it is an uppercase letter that corresponds to the hour (in a 24-hour clock) that the identifier was created. For example, a file created in hour three of the day will have a D prefixed (the hour begins at midnight with A). [2] [2] Programs should not depend on the lead letter actually encoding the hour. It is intended only to ensure that all identifiers be unique within any 24-hour period and as an aid to scripts that need to extract information from log files. If sendmail cannot create an exclusive filename (because a file with that identifier already exists), it clocks the second A of the AA to a B and tries again. It continues this process, clocking the right-hand letter from A to Z and the left-hand letter from A to ~ until it succeeds: AA start AB second try AC third try ... and so on ~W ~X ~Y last try ~Z failure If it never succeeds, the ident ultimately looks like the following and sendmail has failed: hour~Zpid This ident is unlikely to ever appear, because the clocking provides for over 1600 possibilities. All the files associated with a given mail message share the same ident as a part of their filenames. The individual files associated with a single mail message differ only in the first letter of their names. AApid prior to V8.6 hourAApid beginning with V8.6 confMESSAGEID_HEADER Message-Id: [<$t.$i@$j>] The format of an internally generated Message-Id: header. LINE 580 H?M?Resent-Message-Id: <$t.$i@$j> H?M?Message-Id: <$t.$i@$j> http://www.expita.com/header1.html Message-ID: (also Message-Id: or Message-id:) This field is like a serial number and contains a unique identifier (the local-part address unit) which refers to THIS version of THIS message. The uniqueness of the message identifier is guaranteed by the host which generates it. This identifier is intended to be machine readable and not necessarily meaningful to humans. A message identifier pertains to exactly one particular message; subsequent revisions to the message should each receive new message identifiers. sendmail constructs the field from the data, the time, a unique file name, and the originating machine name. Message-ID: <02ba01c07ad8$898fc840$c900000a@checkoway.com> Message-ID:にゃんたろう 拝！
2005年 5月23日 (月) 22:35:50 JST 作成