1. A method of performing an action in response to a file system event, the method comprising: in response to user input, storing (a) data that defines a specified condition and (b) data that associates the specified condition with the file system event; detecting that the file system event has occurred or is going to occur relative to a node within a file system; and in response to detecting that the file system event has occurred or is going to occur relative to the node, performing steps comprising: determining whether any condition is associated with the file system event; in response to determining that the specified condition is associated with the file system event, reading the data that defines the specified condition; based on the data that defines the specified condition, determining whether the specified condition is satisfied; in response to determining that the specified condition is satisfied, performing a specified action; and in response to determining that the specified condition is not satisfied, refraining from performing the specified action.