sendmail, 4th Edition

$&

Delay macro expansion until runtime LHS and RHS operator

Normally, sendmail macros are expanded ( replaced with their values) when the configuration file is read. For those situations when a sendmail macro should not be expanded, but rather should be used in rules as is, V8 sendmail offers the $& prefix. For example, consider the following RHS of a rule:

 R...     $w.$&M 

Normally, when sendmail encounters this RHS in the configuration file, it will recursively expand $w into its final text value (where that text value is your hostname, such as wash.dc.gov ). But because the M sendmail macro is prefixed (here, with $& ) it is not expanded until the rule is processed .

The $& operator can be used in either the LHS or RHS of a rule. The $& operator is described in full in Section 21.5.3.



Sendmail
sendmail, 4th Edition
ISBN: 0596510292
EAN: 2147483647
Year: 2002
Pages: 1174

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