sendmail, 4th Edition

Rebuild Aliases Mode (-bi)

Because sendmail might have to search through thousands of names in the aliases file, a version of the file is stored in a separate dbm(3) or db(3) database format file. The use of a database significantly improves lookup speed.

Although early versions of sendmail can automatically update the database whenever the aliases file is changed, that is no longer possible with modern versions.^[18] Now, you need to rebuild the database yourself, either by running sendmail using the command newaliases or with the -bi command-line switch. Both do the same thing:

% newaliases
% /usr/lib/sendmail -bi

There will be a delay while sendmail rebuilds the aliases database; then a summary of what it did is printed:

/etc/mail/aliases: 859 aliases, longest 615 bytes, 28096 bytes total

This line shows that the database was successfully rebuilt. Beginning with V8.6 sendmail, multiple alias files became possible, so each line (and there might be many) begins with the name of an alias file. The information then displayed is the number of aliases processed, the size of the biggest entry to the right of the : in the aliases file, and the total number of bytes entered into the database. Any mistakes in an alias file will also be printed here.

The aliases file and how to manipulate it are covered in Chapter 12 on page 460.

^{[18] *} Beginning with V8.10 sendmail, it was recognized that auto-rebuilding the aliases file posed a security risk. For versions V8.10 and V8.11 use of this function ...