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Rev	Author	Line No.	Line
2	-	1	`.TH VAC 1`
		2	`.SH NAME`
		3	`vac, unvac \- create, extract a vac archive on Venti`
		4	`.SH SYNOPSIS`
		5	`.B vac`
		6	`[`
		7	`.B -mqsv`
		8	`] [`
		9	`.B -b`
		10	`.I blocksize`
		11	`] [`
		12	`.B -d`
		13	`.I oldvacfile`
		14	`] [`
		15	`.B -e`
		16	`.I exclude`
		17	`] [`
		18	`.B -f`
		19	`.I vacfile`
		20	`] [`
		21	`.B -i`
		22	`.I name`
		23	`] [`
		24	`.B -h`
		25	`.I host`
		26	`]`
		27	`.I file ...`
		28	`.PP`
		29	`.B unvac`
		30	`[`
		31	`.B -Tctv`
		32	`] [`
		33	`.B -h`
		34	`.I host`
		35	`]`
		36	`.I vacfile`
		37	`[`
		38	`.I file ...`
		39	`]`
		40	`.SH DESCRIPTION`
		41	`.I Vac`
		42	`creates an archival copy of Plan 9 file trees on Venti. It can be used`
		43	`to build a simple backup system. One of the unusual properties of Venti is`
		44	`that duplicate blocks are detected and coalesced. When`
		45	`.I vac`
		46	`is used on a file tree that shares data with an existing archive, the consumption of`
		47	`storage will be approximately equal to an incremental backup.`
		48	`This reduction in storage consumption occurs transparently to the user.`
		49	`.PP`
		50	`As an optimization, the`
		51	`.B -d`
		52	`and`
		53	`.B -q`
		54	`options, described below, can be used to explicitly create an archive relative to an existing archive.`
		55	`These options do not change the resulting archive generated by`
		56	`.IR vac ,`
		57	`but simply reduce the number of write operations to Venti.`
		58	`.PP`
		59	`The output of`
		60	`.I vac`
		61	`is the hexadecimal representation of the SHA1 fingerprint of the root of the archive, in this format:`
		62	`.IP`
		63	`.EX`
		64	`vac:64daefaecc4df4b5cb48a368b361ef56012a4f46`
		65	`.EE`
		66	`.PP`
		67	`The options to`
		68	`.I vac`
		69	`are:`
		70	`.TF "-d\fI oldvacfile"`
		71	`.PD`
		72	`.TP`
		73	`.BI -b " blocksize`
		74	`Specifies the block size that data will be broken into.`
		75	`The units for the size can be specified by appending`
		76	`.L k`
		77	`to indicate kilobytes.`
		78	`The default is 8k.`
		79	`The size must be in the range`
		80	`of 512 bytes to 52k.`
		81	`.TP`
		82	`.BI -d " oldvacfile`
		83	`Reduce the number of blocks written to Venti by comparing the files to be stored with`
		84	`the contents of an existing`
		85	`.I vac`
		86	`file tree whose score is stored in`
		87	`.IR oldvacfile .`
		88	`.TP`
		89	`.BI -e " exclude`
		90	`Do not include the file or directory specified by`
		91	`.IR exclude .`
		92	`This option may be repeated multiple times.`
		93	`.TP`
		94	`.BI -f " vacfile`
		95	`The results of`
		96	`.I vac`
		97	`are placed in`
		98	`.IR vacfile ,`
		99	`or the standard output if no file is given.`
		100	`.TP`
		101	`.BI -i " name`
		102	`Include standard input as one of the input files, storing it in the archive`
		103	`with the specified`
		104	`.IR name .`
		105	`.TP`
		106	`.BI -h " host`
		107	`The network address of the Venti server.`
		108	`The default is taken from the environment variable`
		109	`.BR venti .`
		110	`If this variable does not exist, then the default is the`
		111	`metaname`
		112	`.BR $venti ,`
		113	`which can be configured via`
		114	`.IR ndb (6).`
		115	`.TP`
		116	`.B -m`
		117	`Expand and merge any`
		118	`.I vac`
		119	`archives that are found while reading the input files. This option is`
		120	`useful for building an archive from a collection of existing archives. Each archive is inserted`
		121	`into the new archive as if it had been unpacked in the directory in which it was found. Multiple`
		122	`archives can be unpacked in a single directory and the contents will be merged. To be detected, the`
		123	`archives must end in`
		124	`.LR .vac .`
		125	`Note, an archive is inserted by simply copying the root fingerprint and does not require`
		126	`the archive to be unpacked.`
		127	`.TP`
		128	`.B -q`
		129	`Increase the performance of the`
		130	`.B -d`
		131	`option by detecting unchanged files based on a match of the files name and other meta data,`
		132	`rather than examining the contents of the files.`
		133	`.TP`
		134	`.B -s`
		135	`Print out various statistics on standard error.`
		136	`.TP`
		137	`.B -v`
		138	`Produce more verbose output on standard error, including the name of the files added to the archive`
		139	`and the vac archives that are expanded and merged.`
		140	`.PP`
		141	`.I Unvac`
		142	`lists or extracts files stored in the vac archive`
		143	`.IR vacfile ,`
		144	`which can be either a vac archive string in the format`
		145	`given above or the name of a file containing one.`
		146	`If`
		147	`.I file`
		148	`arguments are given, only those files or directories`
		149	`will be extracted.`
		150	`The options are:`
		151	`.TP`
		152	`.B -T`
		153	`Set the modification time on extracted files`
		154	`to the time listed in the archive.`
		155	`.TP`
		156	`.B -c`
		157	`Write extracted files to standard output instead of creating a file.`
		158	`.TP`
		159	`.B -h`
		160	`as per`
		161	`.IR vac .`
		162	`.TP`
		163	`.B -t`
		164	`Print a list of the files to standard output rather than extracting them.`
		165	`.TP`
		166	`.B -v`
		167	`If extracting files, print the name of each file and directory`
		168	`to standard error.`
		169	`If listing files, print metadata in addition to the names.`
		170	`.SH SOURCE`
		171	`.B /sys/src/cmd/vac`
		172	`.SH "SEE ALSO"`
		173	`.IR vacfs (4),`
		174	`.IR venti (8)`

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