Implement pre-create and post-create hooks.

[dss.git] / dss.ggo

diff --git a/dss.ggo b/dss.ggo
index 51cfadd3391b41d4636c29b07411f93063a06413..171142eb1bc730d47d01437a78278af113ba1836 100644 (file)
--- a/dss.ggo
+++ b/dss.ggo
@@ -243,29 +243,34 @@ option "pre-create-hook" r
 #~~~~~~~~~~~~~~~~~~~~~~~~~~
 "Executed before snapshot creation"
 string typestr="command"
-default="/bin/true"
 optional
 details="
        Execute this command before trying to create a new snapshot.
-       If this command returns with a non-zero exit status, do not
-       perform the backup. One possible application of this is to
-       return non-zero during office hours in order to not slow down
-       the file systems by taking snapshots.
-"
+       If this command returns with a non-zero exit status, no
+       snapshot is being created and the operation is retried later.
+
+       For example, one might want to execute a script that checks
+       whether all snapshot-related file systems are properly mounted.
 
+       Another possible application of this is to return non-zero
+       during office hours in order to not slow down the file systems
+       by taking snapshots.
+"
 
 option "post-create-hook" o
 #~~~~~~~~~~~~~~~~~~~~~~~~~~
 "Executed after snapshot creation"
 string typestr="command"
-default="/bin/true"
 optional
 details="
-       Execute this after a snapshot has successfully been created
-       The return value on the command is ignored. For instance one
-       could count the number of files per user and/or the disk
-       usage patterns in order to store them in a database for
-       further treatment.
+       Execute this after a snapshot has successfully been
+       created. The full path of the newly created snapshot is passed
+       to the hook as the first argument.  The return value of that
+       hook is ignored.
+
+       For instance this hook can be used to count the number of
+       files per user and/or the disk usage patterns in order to
+       store them in a database for further treatment.
 "
 
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