•
A key's operation is determined by the operator. udev rules support several different
operators.
• Each given value must be enclosed by quotation marks.
• Each line of the rules le represents one rule. If a rule is longer than just one line,
use \ to join the different lines just as you would do in shell syntax.
•
udev rules support a shell-style pattern that matches the *, ?, and [] patterns.
•
udev rules support substitutions.
12.6.1
Using Operators in udev Rules
Creating keys you can choose from several different operators, depending on the type
of key you want to create. Match keys will normally just be used to nd a value that
either matches or explicitly mismatches the search value. Match keys contain either of
the following operators:
==
Compare for equality. If the key contains a search pattern, all results matching this
pattern are valid.
!=
Compare for non-equality. If the key contains a search pattern, all results matching
this pattern are valid.
Any of the following operators can be used with assign keys:
=
Assign a value to a key. If the key previously consisted of a list of values, the key
resets and only the single value is assigned.
+=
Add a value to a key that contains a list of entries.
:=
Assign a nal value. Disallow any later change by later rules.
Dynamic Kernel Device Management with udev 213
