33.3.4.1 -A append values for duplicate keys (V8.7 and above)

Ordinarily, when sendmail builds (rebuilds) an aliases database, it objects to duplicate keys on the left of the colon:

staff:  bill
staff:  leopold         this is an error

But sometimes, in automating for example, such duplicates are necessary. In such instances, the -A switch can be used with the AliasFile (A) option (see Section 34.8.1, AliasFile (A)) to cause duplicates to be silently appended:

staff:  bill
staff:  leopold
... silently modified by sendmail to internally become
staff:  bill, leopold

Note that this process is further illustrated in Section 24.4.4, "Duplicate Entries and Automation".

The -A database switch is useful only with alias files, because those are the only files that sendmail rebuilds on its own.

33.3.4.2 -a append tag on successful match (V8.1 and above)

When a key is looked up in a database (from inside the $( and $) operators of the RHS of rules), a successfully found key is replaced by its data. If the -a switch is given, the text following that switch, up to the first delimiting whitespace character, is appended to the replacement data. For example:

-a              appends  nothing
-a.             appends  .
-a,MAGICTOKEN   appends  ,MAGICTOKEN

The text to be appended is taken literally. Quotation marks and backslashed characters are included without interpretation, so whitespace cannot be included in that text. Because the rewritten RHS is normalized as an address, special address expressions (such as parentheses) should be avoided. The use of appended text is one of two methods used for recognizing a successful lookup in rules. We'll discuss the other, $:, in Section 33.4.1, "Specify a Default with $:".

33.3.4.3 -f don't fold keys to lowercase (V8.1 and above)

Ordinarily, sendmail will normalize a key to lowercase before looking it up in the database. If the keys in the database are case-sensitive ("TEX" is considered different from "tex," for example), the -f switch should be used to prevent this normalization. Note that if the -f switch is omitted (the default), the database must have been created with all lowercase keys (also the default).

33.3.4.4 -k specify column for key (V8.7 and above)

Beginning with V8.7, sendmail began to support a flat text-file form of database. The /etc/hosts file is an example of such a flat file, in that it is organized in a line-by-line manner:

123.45.67.89      here.our.domain

When such files are read as databases (with the text class; see Section 33.8.18), you need to specify which column is the key and which is the value.

For nisplus and netinfo maps, the -k switch specifies the name (text) of the desired column.

When the -k switch specifies which column is the key, its absence defaults to 0 for the text class and to the name of the zeroth column for the nisplus class. Note that the numbered columns are indexed beginning with 0 for the first and 1 for the second. See also -v (see Section 33.3.4.11) for the value's column (text and nisplus only) and -z (see Section 33.3.4.12) for the column delimiter (text only).

33.3.4.5 -m suppress replacement on match (V8.1 and above)

Ordinarily, a successful lookup in a database or map causes the key to be replaced by its value. When the intention is to merely verify that the key exists (not replace it), the -m switch can be used to suppress replacement. For example, the values that are returned from the hosts.byname NIS map are not generally useful (they contain multiple hostnames). In looking up a key in this map (with $( and $); see Section 33.4), the -m switch prevents those multiple names from wrongly replacing the single hostname in the key. Note that the -a (see Section 33.3.4.2) can still be used to append a suffix to a successful lookup. Also, the $:default (see Section 33.4.1) is still used if the lookup fails.

33.3.4.6 -N append a null byte to all keys (V8.1 and above)

If a database was created with makemap's -N switch (see Section 33.2.1.3) to include the terminating zero byte with each key, this K configuration command -N switch may be specified to force all lookups to also include a zero byte. Note that -N is not needed for the nis class and, if included, is ignored. See also -O below.

33.3.4.7 -O adaptive versus never add a null (V8.2 and above)

If neither -N nor -O is specified, sendmail uses an adaptive algorithm to decide whether or not to look for the terminating zero byte. The algorithm starts by accepting either. If the first key looked up is found to end with a terminating zero byte, the algorithm will thereafter look only for keys with terminating zero bytes. If the first key that is looked up is found to not end with a terminating zero byte, the algorithm will thereafter look only for keys without terminating zero bytes.

If this -O switch is specified, sendmail never tries a zero byte, which can speed matches. Note that if both -N and -O are specified, sendmail will never try to match at all, thus causing all lookups to appear to fail.

33.3.4.8 -o the database file is optional (V8.1 and above)

Ordinarily, sendmail will complain if a database file cannot be opened for reading. If the presence of a database file is optional (as it may be on certain machines), the -o switch should be used to tell sendmail that the database is optional. Note that if a database is optional and cannot be opened, all lookups will silently fail for rules that use that database.

33.3.4.9 -q don't strip quotes from key (V8.7 and above)

Ordinarily, sendmail strips all the nonescaped quotation marks (those not prefixed with a backslash) from a key before looking it up. For example, the following key:

"Bob \"bigboy\" Roberts \(esq\)"@bob.com

will have its nonescaped quotation marks removed to end up like this:

Bob "bigboy" Roberts (esq)@bob.com

Note that all escaped characters are de-escaped (have the backslash removed) during this process.

When quotation marks and escaped characters need to be preserved in a key before it is looked up, you can use the -q switch with the K configuration command. The -q switch suppresses dequoting and de-escaping.

33.3.4.10 -s space replacement character (V8.7 and above)

The dequote class (see Section 33.8.4) refuses to remove quotation marks if doing so will result in an illegal address. For example, internal space characters are illegal in addresses:

"a b"           becomes       "a b"

The -s switch causes all the quoted space characters to be changed into a character that you specify just before the dequoting process.

Kdequote dequote -s+

Here, we specify that quoted strings will have quoted spaces converted into a plus before dequoting. Therefore, the above conversion becomes the following:

"a b"           becomes       a+b

The -s switch is only of use with the dequote class. Note that the lpadx class uses the -s switch differently (see Table 33.6 in Section 33.3.4, "The switches").

33.3.4.11 -v specify the value's column (V8.7 and above)

The manner in which the key and its value are visually displayed in flat, sequential, text files and certain network services, may not be directly suitable for use in maps. A text class file, for example /etc/hosts, may display the key on the right and the value on the left:

123.45.67.89      here.our.domain

For such circumstances the -v switch can be used with the K command to specify the column or item that will be returned as the value when a key is matched. For example:

Kaddr text -k1 -v0 /etc/hosts

For nisplus and netinfo maps, the -v switch specifies the name (text) of the value's column.

This -v switch specifies which column is the value to return. If it is omitted, it defaults to 0 for the text class and to the last named column for the nisplus class. Note that text columns are indexed beginning with 0 for the first and 1 for the second. See also -k (see Section 33.3.4.4) for the key's column and -z (see Section 33.3.4.12) for the column delimiter.

33.3.4.12 -z specify the column delimiter (V8.7 and above)

Flat, sequential text files have columns of information delimited from each other with a variety of characters:

123.45.67.89      here.our.domain           /etc/hosts uses a whitespace
nobody:*:65534:65534::/:                    /etc/passwd uses a colon

The -z switch can be used to specify a delimiter whenever the default delimiter of whitespace is not appropriate. In the case of the /etc/passwd file, a database declaration might look like this:

Kuid text -z: -k2 -v0 /etc/passwd  # map to convert uid to login name

The default is whitespace for the text class. It is a comma for the netinfo class.