Sequence Number Substitutions ($#...#)

A $#...# substitution increments the value stored in an MTA sequence file and substitutes that value into the template. This can be used to generate unique, increasing strings in cases where it is desirable to have a unique qualifier in the mapping table output; for instance, when using a mapping table to generate file names.

Permitted syntax is any one of the following:

$#seq-file-spec|radix|width|m#

$#seq-file-spec|radix|width#

$#seq-file-spec|radix#

$#seq-file-spec#

The required seq-file-spec argument is a full file specification for an already existing MTA sequence file. The optional radix and width arguments specify the radix (base) in which to output the sequence value, and the number of digits to output, respectively. The default radix is 10. Radices in the range -36 to 36 are also allowed; for instance, base 36 gives values expressed with digits 0,...,9,A,...,Z. By default, the sequence value is printed in its natural width, but if the specified width calls for a greater number of digits, then the output is padded with 0s on the left to obtain the correct number of digits. Note that if a width is explicitly specified, then the radix must be explicitly specified also.

The optional m argument is a modulus. If this fourth argument is specified the value inserted is the sequence number retrieved from the file mod m. The default is not to perform any modulus operation.

As noted above, the MTA sequence file referred to in a mapping must already exist. To create an MTA sequence file, use the following UNIX command:

touch seq-file-spec

or

cat >seq-file-spec

               

A sequence number file accessed using a mapping table must be world readable in order to operate properly. You must also have an MTA user account (configured to be nobody in the imta_tailor file) in order to use such sequence number files.