vac.1 (5412B)
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 -a 10 .I vacfile 11 ] [ 12 .B -b 13 .I blocksize 14 ] [ 15 .B -d 16 .I oldvacfile 17 ] [ 18 .B -e 19 .I exclude 20 ] [ 21 .B -f 22 .I vacfile 23 ] [ 24 .B -i 25 .I name 26 ] [ 27 .B -h 28 .I host 29 ] [ 30 .B -x 31 .I excludefile 32 ] 33 .I file ... 34 .PP 35 .B unvac 36 [ 37 .B -Tcdtv 38 ] [ 39 .B -h 40 .I host 41 ] 42 .I vacfile 43 [ 44 .I file ... 45 ] 46 .SH DESCRIPTION 47 .I Vac 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 51 .I vac 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. 55 .PP 56 As an optimization, the 57 .B -d 58 and 59 .B -q 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 62 .IR vac , 63 but simply reduce the number of write operations to Venti. 64 .PP 65 The output of 66 .I vac 67 is the hexadecimal representation of the SHA1 fingerprint of the root of the archive, in this format: 68 .IP 69 .EX 70 vac:64daefaecc4df4b5cb48a368b361ef56012a4f46 71 .EE 72 .PP 73 The options are: 74 .TP 75 .BI -a " vacfile 76 Specifies that vac should create or update a backup archive, inserting 77 the files under an extra two levels of directory hierarchy named 78 .I yyyy/mmdd 79 (year, month, day) 80 in the style of the dump file system 81 (see Plan 9's 82 .IR fs (4)). 83 If 84 .I vacfile 85 already exists, an additional backup day is added to the 86 existing hierarchy, behaving as though the 87 .B -d 88 flag was specified giving the most recent backup tree in the archive. 89 Typically, this option 90 is used as part of a nightly backup script. 91 This option cannot be used with 92 .B -d 93 or 94 .BR -f . 95 .TP 96 .BI -b " blocksize 97 Specifies the block size that data will be broken into. 98 The units for the size can be specified by appending 99 .L k 100 to indicate kilobytes. 101 The default is 8k. 102 The size must be in the range 103 of 512 bytes to 52k. 104 .TP 105 .BI -d " oldvacfile 106 Reduce the number of blocks written to Venti by comparing the files to be stored with 107 the contents of an existing 108 .I vac 109 file tree whose score is stored in 110 .IR oldvacfile . 111 .TP 112 .BI -e " exclude 113 Do not include the file or directory specified by 114 .IR exclude . 115 This option may be repeated multiple times. 116 .I Exclude 117 can be a shell pattern as accepted by 118 .MR rc (1) , 119 with one extension: 120 .B \&... 121 matches any sequence of characters including slashes. 122 .TP 123 .BI -f " vacfile 124 The results of 125 .I vac 126 are placed in 127 .IR vacfile , 128 or the standard output if no file is given. 129 .TP 130 .BI -i " name 131 Include standard input as one of the input files, storing it in the archive 132 with the specified 133 .IR name . 134 .TP 135 .BI -h " host 136 The network address of the Venti server. 137 The default is taken from the environment variable 138 .BR venti . 139 .\" If this variable does not exist, then the default is the 140 .\" metaname 141 .\" .BR $venti , 142 .\" which can be configured via 143 .\" .IR ndb (6). 144 .TP 145 .B -m 146 Expand and merge any 147 .I vac 148 archives that are found while reading the input files. This option is 149 useful for building an archive from a collection of existing archives. Each archive is inserted 150 into the new archive as if it had been unpacked in the directory in which it was found. Multiple 151 archives can be unpacked in a single directory and the contents will be merged. To be detected, the 152 archives must end in 153 .LR .vac . 154 Note, an archive is inserted by simply copying the root fingerprint and does not require 155 the archive to be unpacked. 156 .TP 157 .B -q 158 Increase the performance of the 159 .B -a 160 or 161 .B -d 162 options by detecting unchanged files based on a match of the files name and other meta data, 163 rather than examining the contents of the files. 164 .TP 165 .B -s 166 Print out various statistics on standard error. 167 .TP 168 .B -v 169 Produce more verbose output on standard error, including the name of the files added to the archive 170 and the vac archives that are expanded and merged. 171 .TP 172 .BI -x " excfile 173 Read exclude patterns from the file 174 .IR excfile . 175 Blank lines and lines beginning with 176 .B # 177 are ignored. 178 All other lines should be of the form 179 .B include 180 .I pattern 181 or 182 .B exclude 183 .I pattern . 184 When considering whether to include a directory or file 185 in the vac archive, 186 the earliest matching pattern in the file 187 applies. 188 The patterns are the same syntax accepted by the 189 .B -e 190 option. 191 This option may be repeated multiple times. 192 .PP 193 .I Unvac 194 lists or extracts files stored in the vac archive 195 .IR vacfile , 196 which can be either a vac archive string in the format 197 given above or the name of a file containing one. 198 If 199 .I file 200 arguments are given, only those files or directories 201 will be extracted. 202 The options are: 203 .TP 204 .B -T 205 Set the modification time on extracted files 206 to the time listed in the archive. 207 .TP 208 .B -c 209 Write extracted files to standard output instead of creating a file. 210 .TP 211 .B -d 212 Reduce the number of blocks read from Venti by 213 comparing the files to be stored with their counterparts 214 in the file system. 215 This option cannot be used with 216 .BR -c . 217 .TP 218 .B -t 219 Print a list of the files to standard output rather than extracting them. 220 .TP 221 .B -v 222 If extracting files, print the name of each file and directory 223 to standard error. 224 If listing files, print metadata in addition to the names. 225 .SH SOURCE 226 .B \*9/src/cmd/vac 227 .SH "SEE ALSO" 228 .MR vacfs (4) , 229 .MR venti (8)