5 \h'-\w'\fB\\$1\ \fP'u'\fB\\$1\ \fP\c
7 .TH snaptab 5 "6 November 2011" "distorted.org.uk backup"
9 snaptab \- device-level snapshot parameters
13 file describes mechanisms and parameters for taking snapshots of block
16 program by default reads
17 .BR @sysconfdir@/snaptab ,
18 but it can be instructed to read a different file using the
22 The file consists of a sequence of logical lines. A logical line
23 consists of one or more newline-terminated physical lines, all but the
24 last of which ends with a backslash
26 followed by zero or more whitespace characters. These trailing
27 backslashes and trailing whitespace are stripped from the logical line
28 during parsing, and are not further significant.
32 consisting only of whitespace;
35 beginning with zero or more whitespace characters followed by a
39 Empty lines and comments are ignored.
41 A data line consists of two or more whitespace-separated fields. There
42 may be leading or trailing whitespace; this is not significant.
43 Whitespace characters may be included in a field using escaping or
44 quoting, in a manner similar to the Bourne shell, though it is not
45 possible for a field to contain a newline character.
47 The precise quoting and escaping rules are as follows. All characters
48 other than whitespace (i.e., space, horizontal and vertical tabs, and
49 formfeed), the backslash
57 and have no special meaning. A character preceded by an unescaped
60 any other character is
62 If an unquoted, unescaped double- or single-quote character occurs, the
63 following characters, up until but not including the next unescaped
64 occurrence of the same quote character, are
68 respectively; other characters are
72 if it is ordinary, escaped, single-quoted, or both double-quoted and not
73 a backslash. A field's text consists of all of the constituent
74 characters bounded by the start of the line, the end of the line, or
75 sequences of one or more unescaped, unquoted whitespace characters.
77 The fields of a data line are as follows.
79 .I "device type option \fR..."
80 Briefly, the fields are interpreted as follows. A full description is
84 The name of a device which can be snapshot. This is usually the name of
89 prefix, though strictly speaking its interpretation is left up to the
90 snapshot handler program. Alternatively, this can be the special name
92 to define default options for a particular snapshot type.
95 The type of snapshot to be performed. For each snapshot type, there is
98 which manages snapshots of that type.
101 The remaining fields are option assignments: these are either individual
103 assignments, or tokens of the form
105 to interpolate the current default options for the given
108 The configuration file's data lines describe a mapping from
114 This section describes how the mapping is derived from the file
121 are arbitrary strings, and
123 are strings of the form
127 is a nonempty string which contains no
131 is an arbitrary string. An option of the form
132 .IB key . type = value
135 otherwise, an option is
137 In a qualified option, the
147 assignments, which are not further interpreted, and various special
148 tokens. These tokens are replaced with other options or sequences of
151 The following tokens are recognized during expansion, and replaced.
154 The replacement sequence is constructed as follows. Start with the
155 default option sequence for the
157 for this line (see below). Each qualified option in this sequence is
158 retained; each unqualified option
163 .IB key . type = value \fR.
166 .I "default option sequence"
170 at a given line in the file is the concatenation of the expanded option
171 sequences of all earlier data lines whose
180 The option sequence of a data line whose
186 by prefixing the expanded option sequence with the default option
187 sequence for the corresponding
191 It is an error if two data lines with equal
193 fields have different
206 sequences can now be defined. Collect all of the data lines whose
208 field matches the input
212 field from these lines is the resulting
214 The resulting option sequence is the concatenation of the augmented
215 option sequences for the collected lines.
219 program filters the option sequence, retaining only the last option with
223 Consider the file below.
227 .ta 8 16 24 32 40 48 56 64
236 ## Local filesystems.
240 vg-ibanez/scratch lvm
244 ## Remotely mounted filesystems.
245 * rfreezefs host=roadstar
246 vg-ibanez/db rfreezefs dir=/mnt/db
247 vg-ibanez/ftp rfreezefs dir=/mnt/ftp
248 vg-ibanez/news rfreezefs dir=/var/spool/news
251 vg-ibanez/homes rfreezefs dir=/home
252 vg-ibanez/jb rfreezefs dir=/mnt/jb
260 line, the default option list for type
264 and the default option list for type
268 .BR snapsz.lvm=5%ORIGIN .
275 .BR snapsz=5%ORIGIN .
283 .B snapsz.lvm=5%ORIGIN
293 .B snapsz.lvm=5%ORIGIN
299 option is significant \(en the other will be omitted from the list
301 .BR snap.rfreezefs (8).
305 Mark Wooding, <mdw@distorted.org.uk>