Implement pre-create and post-create hooks.

[dss.git] / dss.ggo

diff --git a/dss.ggo b/dss.ggo
index 46b4271936d1ae7e1fe7e958d0ecc7ce55ed876b..171142eb1bc730d47d01437a78278af113ba1836 100644 (file)
--- a/dss.ggo
+++ b/dss.ggo
@@ -21,6 +21,17 @@ details="
        configuration file. As usual, if an option is given both at
        the command line and in the configuration file, the command
        line option takes precedence.
+
+       However, there is an important exception to this rule:
+       If the --run option was given (see below) then dss honors
+       SIGHUP and re-reads its configuration file whenever it
+       receives this signal. In this case the options in the config
+       file override any options that were previously given at the
+       command line. This allows to change the configuration of a
+       running dss process on the fly by sending SIGHUP.
+
+       Note that it is not possible to change whether dss runs as
+       background daemon by sending SIGHUP.
 "
 
 option "daemon" d
@@ -146,7 +157,7 @@ option "source-dir" -
 #~~~~~~~~~~~~~~~~~~~~
 "The data directory"
 string typestr="dirname"
-optional
+required
 details="
        The directory on the remote host from which snapshots are
        taken.  Of course, the user specified as --remote-user must
@@ -157,7 +168,7 @@ option "dest-dir" -
 #~~~~~~~~~~~~~~~~~~
 "Snapshot dir"
 string typestr="dirname"
-optional
+required
 details="
        The destination directory on the local host where snapshots
        will be written. This must be writable by the user who runs
@@ -232,29 +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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