Introduce get_config_file_name().

[dss.git] / dss.ggo

diff --git a/dss.ggo b/dss.ggo
index b5eeba8352b9c116b00565487c5af0389c14c6cd..1662e0d36f514491c1029e674bc407a98012942d 100644 (file)
--- a/dss.ggo
+++ b/dss.ggo
@@ -1,6 +1,9 @@
+# Copyright (C) 2008-2010 Andre Noll <maan@systemlinux.org>

 #
 #

+# Licensed under the GPL v2. For licencing details see COPYING.
+

 package "dss"
 package "dss"

-version "0.0.4"
+version "0.1.4"

 purpose "the dyadic snapshot scheduler
 
 dss creates hardlink-based snapshots of a given directory on a remote
 purpose "the dyadic snapshot scheduler
 
 dss creates hardlink-based snapshots of a given directory on a remote


@@ -74,17 +77,23 @@ option "logfile" -
 "Logfile for the dss daemon process"
 string typestr="filename"
 optional
 "Logfile for the dss daemon process"
 string typestr="filename"
 optional

-details="
-       This option is mostly useful for the run command if --daemon
-       is also given.
+details = "
+       This option is only honored if both --run and --daemon are
+       given. Otherwise it is silently ignored and log output is
+       written to stderr.

 "
 
 "
 

+##################
+section "Commands"
+##################
+

 defgroup "command"
 #=================
 groupdesc="
        dss supports a couple of commands each of which corresponds
        to a different command line option. Exactly one of these
        options must be given.
 defgroup "command"
 #=================
 groupdesc="
        dss supports a couple of commands each of which corresponds
        to a different command line option. Exactly one of these
        options must be given.

+

 "
 required
 
 "
 required
 


@@ -99,13 +108,20 @@ details="
 
 groupoption "prune" P
 #~~~~~~~~~~~~~~~~~~~~
 
 groupoption "prune" P
 #~~~~~~~~~~~~~~~~~~~~

-"Remove a redundant snapshot"
+"Remove redundant and outdated snapshots"

 group="command"
 details="
 group="command"
 details="

-       A snapshot is considered redundant if it ether belongs to
-       an interval greater than the maximum number of intervals,
-       or if it belongs to an interval that already contains more
-       than the desired number of snapshots.
+       A snapshot is considered outdated if its interval number
+       is greater or equal than the specified number of unit
+       intervals. See the \"Intervals\" section below for the precise
+       definition of these terms.
+
+       A snapshot is said to be redundant if it belongs to an
+       interval that already contains more than the desired number
+       of snapshots.
+
+       The prune command gets rid of both outdated and redundant
+       snapshots.

 "
 
 groupoption "ls" L
 "
 
 groupoption "ls" L


@@ -124,7 +140,9 @@ groupoption "run" R
 group="command"
 details="
        This is the main mode of operation. Snapshots will be created
 group="command"
 details="
        This is the main mode of operation. Snapshots will be created

-       as needed and pruned automatically.
+       in an endless loop as needed and pruned automatically. The loop
+       only terminates on fatal errors or if a terminating signal was
+       received. See also the --exit-hook option.

 "
 
 ###############################
 "
 
 ###############################


@@ -177,6 +195,21 @@ details="
        dss.
 "
 
        dss.
 "
 

+option "no-resume" -
+#~~~~~~~~~~~~~~~~~~~
+"Do not try to resume from previous runs"
+flag off
+details = "
+       Starting from version 0.1.4, dss tries to resume from a
+       previously cancelled dss instance by default. It does so by
+       looking at the status of the most recently created snapshot. If
+       this snapshot status is incomplete, its directory is reused
+       as the destination directory for a subsequent rsync run.
+
+       The --no-resume option deactivates this feature so that a new
+       directory is always used as the rsync destination directory.
+"
+

 option "rsync-option" O
 #~~~~~~~~~~~~~~~~~~~~~~
 "Further rsync options"
 option "rsync-option" O
 #~~~~~~~~~~~~~~~~~~~~~~
 "Further rsync options"


@@ -184,8 +217,12 @@ string typestr="option"
 optional
 multiple
 details="
 optional
 multiple
 details="

-       These option may be given multiple times. The arguments passed
-       to that option are passed verbatim to the rsync command.
+       This option may be given multiple times. The given argument is
+       passed verbatim to the rsync command. Note that in order to use
+       rsync options that require an argument, you have to specify the
+       option and its argument as separate --rsync-options, like this:
+
+               --rsync-option --exclude --rsync-option /proc

 "
 
 ###################
 "
 
 ###################


@@ -205,13 +242,14 @@ details="
        unit intervals.
 
        dss removes any snapshots older than n times u and tries to
        unit intervals.
 
        dss removes any snapshots older than n times u and tries to

-       keep 2^(k-1) snapshots in interval k, where the interval number
-       k counts from zero, zero being the most recent unit interval.
+       keep 2^(n - k - 1) snapshots in interval k, where the interval
+       number k counts from zero, zero being the most recent unit
+       interval.

 
        In other words, the oldest snapshot will at most be u * n days
        (= 20 days if default values are used) old.  Moreover, there
        are at most 2^n - 1 snapshots in total (i. e. 31 by default).
 
        In other words, the oldest snapshot will at most be u * n days
        (= 20 days if default values are used) old.  Moreover, there
        are at most 2^n - 1 snapshots in total (i. e. 31 by default).

-       Observe that you have to create at least 2 ^ (n - 1) snapshots
+       Observe that you have to create at least 2^(n - 1) snapshots

        each interval for this to work out because that is the number
        of snapshots in interval zero.
 "
        each interval for this to work out because that is the number
        of snapshots in interval zero.
 "


@@ -231,6 +269,7 @@ option "pre-create-hook" r
 #~~~~~~~~~~~~~~~~~~~~~~~~~~
 "Executed before snapshot creation"
 string typestr="command"
 #~~~~~~~~~~~~~~~~~~~~~~~~~~
 "Executed before snapshot creation"
 string typestr="command"

+default = "true"

 optional
 details="
        Execute this command before trying to create a new snapshot.
 optional
 details="
        Execute this command before trying to create a new snapshot.


@@ -249,16 +288,69 @@ option "post-create-hook" o
 #~~~~~~~~~~~~~~~~~~~~~~~~~~
 "Executed after snapshot creation"
 string typestr="command"
 #~~~~~~~~~~~~~~~~~~~~~~~~~~
 "Executed after snapshot creation"
 string typestr="command"

+default = "true"

 optional
 details="
        Execute this after a snapshot has successfully been
 optional
 details="
        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.
+       created. The full path of the newly created snapshot is
+       passed to the hook as the first argument.  The exit code of
+       this 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
 
        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.
+       store them in a database for further analysis.
+"
+
+option "pre-remove-hook" -
+#~~~~~~~~~~~~~~~~~~~~~~~~~~
+"Executed before snapshot removal"
+string typestr="command"
+default = "true"
+optional
+details="
+       Execute this command before removing a snapshot. The full
+       path to the snapshot about to be deleted is passed to the
+       command as the first argument. If the command returns with
+       a non-zero exit status, no snapshot is being removed and the
+       operation is retried later.
+
+       For example, one might want to execute a script that checks
+       whether the snapshot to be deleted is currently used by
+       another process, e.g. by a tape-based backup system that runs
+       concurrently to dss.
+
+       Another possible application of this is to record disk-usage
+       patterns before and after snapshot removal.
+"
+
+option "post-remove-hook" -
+#~~~~~~~~~~~~~~~~~~~~~~~~~~
+"Executed after snapshot removal"
+string typestr="command"
+default = "true"
+optional
+details="
+       Execute this after a snapshot has successfully been removed. As
+       for the pre-remove hook, the full path of the removed snapshot
+       is passed to the hook as the first argument. The exit code
+       of this hook is ignored.
+"
+
+option "exit-hook" e
+#~~~~~~~~~~~~~~~~~~~
+"Executed if run command exits"
+string typestr="command"
+default = "true"
+optional
+details="
+       This hook is only used if the --run command was given which
+       instructs dss to run in an endless loop. The exit-hook gets
+       executed whenever this endless loop terminates. The reason
+       for terminating the loop is passed as the first argument.
+
+       One possible application for this hook is to send email to the
+       system administrator to let her know that no more snapshots
+       are going to be created.

 "
 
 ###############################
 "
 
 ###############################


@@ -303,13 +395,28 @@ optional
 details="
        Specify the minimum amount of free inodes on the file system
        containing the destination dir. If less than that many inodes
 details="
        Specify the minimum amount of free inodes on the file system
        containing the destination dir. If less than that many inodes

-       are free, snatshot removal kicks in just as in case of low
+       are free, snapshot removal kicks in just as in case of low

        disk space.
 
        Note that not every file system supports the concept of inodes.
        Moreover it is not possible to reliably detect whether this is
        the case. Therefore this feature is disabled by default. It's
        disk space.
 
        Note that not every file system supports the concept of inodes.
        Moreover it is not possible to reliably detect whether this is
        the case. Therefore this feature is disabled by default. It's

-       safe to enable it for ext3 file systems on linux though.
+       safe to enable it for ext2/ext3/ext4 file systems on linux
+       though.

 
        A value of zero (the default) deactivates this check.
 "
 
        A value of zero (the default) deactivates this check.
 "

+
+option "keep-redundant" k
+#~~~~~~~~~~~~~~~~~~~~~~~~
+"Prune by disk space only"
+flag off
+details="
+       If this flag is not given dss removes redundant and outdated
+       snapshots automatically.
+
+       Otherwise, this feature is deactivated so that snapshots are
+       only being removed in case disk space or number of free inodes
+       becomes low. Use this flag if the file system containing the
+       destination directory is used for snapshots only.
+"