MH-ALIAS(5,F) AIX Technical Reference MH-ALIAS(5,F)
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mh-alias
PURPOSE
Defines aliases for the Message Handling (MH) Package.
DESCRIPTION
The Message Handling (MH) Package supports both personal alias files and a
system-wide alias file, /usr/lib/mh/MailAliases. Depending on the MH
configuration, MH may also honor system-wide alias defined for the sendmail
command. An alias file contains lines that associate an alias name with an
address or a group of addresses.
File Format
Each line of an alias file has one of the following formats:
alias : address-group
alias ; address-group
<file
where
address-group := address-list
| <file
| =AIX-group
| +AIX-group
| "*"
address-list := address
| address-list, address
You can continue an alias definition on the next line by ending the line to be
continued with the \ (backslash) character followed by the new-line character.
The alias-file and file parameters must be AIX file names. AIX-group must be a
group name (or number) from /etc/group. address must be a simple
Internet-style address. MH treats alias file names as case sensitive names but
ignores case elsewhere in alias files.
If a line starts with the "<" (less than) character, MH reads the file
specified after the "<" for more alias definitions. The reading is done
recursively.
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MH-ALIAS(5,F) AIX Technical Reference MH-ALIAS(5,F)
If an address group starts with the "<" (less than) character, MH reads the
file specified after the "<" and adds the contents of that file to the address
list for the alias.
If an address group starts with the "=" (equal) character, MH consults the
/etc/group file for the AIX group specified after the equal character. MH adds
each login name occurring as a member of the group to the address list for the
alias.
If an address group starts with the "+" (plus) character, MH consults the
/etc/group file to determine the group ID of the AIX group specified after the
plus character. MH adds each login name occurring in the /etc/passwd file
whose group ID is indicated by this group to the address list for the alias.
If an address group is specified as "*" (asterisk), MH consults the /etc/passwd
file and adds all login names with a UID greater than 200, or the value set for
everyone in /usr/lib/mh/mtstailor to the address list for the alias.
An approximation of the way the system resolves aliases at posting time:
1. The system builds a list of all addresses from the message to be
delivered, eliminating duplicate addresses.
2. If the draft originated on the local host, the system performs alias
resolution for those addresses in the message that have no host specified.
3. For each line in the alias file, the system compares the alias with all
existing addresses. If a match is found, the system removes the matched
alias from the address list, and adds each new address in the address group
to the address list if it is not already in the list. The alias itself is
not usually output; the address group that the alias maps to is output
instead. If the alias is terminated with a ";" (semicolon) instead of a
":" (colon), both the alias and the address are output in the correct form.
(This correct form makes replies possible since MH aliases and personal
aliases are unknown to the mail transport system.)
In the MH system, aliases in alias files are expanded into the headers of
messages posted. This aliasing occurs first, at posting time, without the
knowledge of the message transport system. In contrast, once the message
transport system is given a message to deliver to a list of addresses, for each
address that appears to be local, a system-wide alias file is consulted. These
aliases are not expanded into the headers of messages delivered.
Since alias files are read line by line, forward references work, but backward
references are not recognized. Although this forward referencing semantics
prevents recursion, the <alias-file syntax may defeat this. Since the number
of file descriptors is limited, such recursion will end when all file
descriptors are depleted.
EXAMPLE
The following example of a mh-alias file illustrates some features:
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MH-ALIAS(5,F) AIX Technical Reference MH-ALIAS(5,F)
</user/lib/mh/DraftingAlias
temps:peggy,tina
tina:temp5@NODE3
p1:<project1.aliases
staff:=staff
support:+syssup
everyone:*
news.*:news
The first line says that more aliases should immediately be read from the file
"/usr/lib/mh/DraftingAliases". Following this, "tina" is defined as an alias
for "temp5@NODE3", and "temps" is defined as an alias for the two names "peggy"
and "tina". The definition of "p1" is given by reading the file
user_mh_directory"/project1.aliases". "staff" is defined as all users who are
listed as members of the group "staff" in the /etc/group file, and "support" is
defined as all users whose group ID in /etc/passwd is equivalent to the
"syssup" group. Finally, "everyone" is defined as all users with a user ID in
/etc/passwd greater than 200, and all aliases of the form "news."anything are
defined to be "news".
FILES
/usr/lib/mh/MailAliases The default system alias file.
/usr/lib/mh/mtstailor The MH tailor file.
RELATED INFORMATION
In this book: "group" and "passwd."
The ali, conflict, post, send, sendmail, and whom commands in AIX Operating
System Commands Reference.
The "Overview of the Message Handling Package" in Managing the AIX Operating
System.
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