3 vac, unvac \- create, extract a vac archive on Venti
48 creates an archival copy of Plan 9 file trees on Venti. It can be used
49 to build a simple backup system. One of the unusual properties of Venti is
50 that duplicate blocks are detected and coalesced. When
52 is used on a file tree that shares data with an existing archive, the consumption of
53 storage will be approximately equal to an incremental backup.
54 This reduction in storage consumption occurs transparently to the user.
56 As an optimization, the
60 options, described below, can be used to explicitly create an archive relative to an existing archive.
61 These options do not change the resulting archive generated by
63 but simply reduce the number of write operations to Venti.
67 is the hexadecimal representation of the SHA1 fingerprint of the root of the archive, in this format:
70 vac:64daefaecc4df4b5cb48a368b361ef56012a4f46
76 .TF "-d\fI oldvacfile"
80 Specifies that vac should create or update a backup archive, inserting
81 the files under an extra two levels of directory hierarchy named
84 in the style of the dump file system
85 (see Plan 9's \fIfs\fR(4)).
88 already exists, an additional backup day is added to the
89 existing hierarchy, behaving as though the
91 flag was specified giving the most recent backup tree in the archive.
92 Typically, this option
93 is used as part of a nightly backup script.
94 This option cannot be used with
100 Specifies the block size that data will be broken into.
101 The units for the size can be specified by appending
103 to indicate kilobytes.
105 The size must be in the range
109 Reduce the number of blocks written to Venti by comparing the files to be stored with
110 the contents of an existing
112 file tree whose score is stored in
116 Do not include the file or directory specified by
118 This option may be repeated multiple times.
120 can be a shell pattern as accepted by
124 matches any sequence of characters including slashes.
131 or the standard output if no file is given.
134 Include standard input as one of the input files, storing it in the archive
139 The network address of the Venti server.
140 The default is taken from the environment variable
142 If this variable does not exist, then the default is the
145 which can be configured via
151 archives that are found while reading the input files. This option is
152 useful for building an archive from a collection of existing archives. Each archive is inserted
153 into the new archive as if it had been unpacked in the directory in which it was found. Multiple
154 archives can be unpacked in a single directory and the contents will be merged. To be detected, the
157 Note, an archive is inserted by simply copying the root fingerprint and does not require
158 the archive to be unpacked.
161 Increase the performance of the
163 option by detecting unchanged files based on a match of the files name and other meta data,
164 rather than examining the contents of the files.
167 Print out various statistics on standard error.
170 Exclude files and directories with the temporary flag set.
173 Produce more verbose output on standard error, including the name of the files added to the archive
174 and the vac archives that are expanded and merged.
177 Read exclude patterns from the file
179 Blank lines and lines beginning with
182 All other lines should be of the form
188 When considering whether to include a directory or file
190 the earliest matching pattern in the file
192 The patterns are the same syntax accepted by the
195 This option may be repeated multiple times.
198 lists or extracts files stored in the vac archive
200 which can be either a vac archive string in the format
201 given above or the name of a file containing one.
204 arguments are given, only those files or directories
209 Set the modification time on extracted files
210 to the time listed in the archive.
213 Write extracted files to standard output instead of creating a file.
216 Reduce the number of blocks read from Venti by
217 comparing the files to be stored with their counterparts
219 This option cannot be used with
223 Print a list of the files to standard output rather than extracting them.
226 If extracting files, print the name of each file and directory
228 If listing files, print metadata in addition to the names.