If a line of an alias file begins with #include, the line is replaced by the contents of the file whose name follows. Other lines, beginning with # are ignored as comment.

Otherwise, lines begin with a name. The rest of a name line gives the expansion. The expansion may contain multiple addresses and may be continued to another line by appending a backslash. Items are separated by white space.

The alias files are searched in the order they are listed, one per line, in /mail/lib/namefiles. If the name is not found, the expansion is taken to be local!name. Under the -f option, alias files listed in /mail/lib/fromfiles are consulted instead, and the domain part only of the expansion is printed.

/mail/lib/namefiles

names of system alias files

/sys/src/cmd/upas/alias