Look up in flat text files |
V8.7 and above |
The
text database-map type allows you to look up keys
in flat text files. This technique is vastly less efficient than
looking up keys in real databases, but it can serve as a way to test
rules before implementing them in database form.
For the text database map, columns for the key and
value are measured as an index. That is, the first column is number
0. To illustrate, consider the following mini-configuration file that
can be used to check spelling:
Kspell text /usr/dict/words
Spell
R$- $: $(spell $1 $: not in dictionary $) The /usr/dict/words file contains only a single
column of words. This rule shows that the key is (by default) the
first column (index 0). And the value is (by default) also the first
column (index 0).
For more sophisticated applications you can specify the
key's column (with the -k
switch), the value's column (with the
-v switch), and the column delimiter (with the
-z switch). To illustrate, consider the need to
look up a user-id in the
/etc/passwd file and to return the login name of
the user to whom it belongs:
Kgetuid text -k2 -v0 -z: /etc/passwd
R$- $: $(getuid $1 $) The lines of a password file look like this: ftp:*:1092:255:File Transfer Protocol Program:/u/ftp:/bin/sh The third column (where the columns are separated by colons) is the
uid field. The first is the login name. Note
that the -k and -v switches
show these fields as indexes, where the first is 0 and the third is
2.
Note that if a file cannot be opened because it is unsafe (DontBlameSendmail), the following warning will be logged and
printed:
text map "name": unsafe map file filename This message will not be printed if the -o switch
is specified with the database-map declaration.
Only a handful of database switches are available with this
text type. The are listed in Table 23-26.
Table 23-26. The text database-map type K command switches
-a
|
-a
|
Append tag on successful match
|
-D
|
-D
|
Don't use this database map if DeliveryMode=defer
|
-f
|
-f
|
Perform a case-insensitive search
|
-k
|
-k
|
Specify column for key or key name
|
-m
|
-m
|
Suppress replacement on match
|
-o
|
-o
|
This database map is optional
|
-q
|
-q
|
Don't strip quotes from key
|
-S
|
-S
|
Space replacement character
|
-T
|
-T
|
Suffix to append on temporary failure
|
-t
|
-t
|
Ignore temporary errors
|
-v
|
-v
|
Specify the value's column
|
-z
|
-z
|
Specify the column delimiter
|
The -d38.20 debugging command-line switch (-d38.20) is available to watch this
text type.
|