160 lines
6.8 KiB
HTML
160 lines
6.8 KiB
HTML
<head>
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<title>vac(1) - Plan 9 from User Space</title>
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<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
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</head>
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<body bgcolor=#ffffff>
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<table border=0 cellpadding=0 cellspacing=0 width=100%>
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<tr height=10><td>
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<tr><td width=20><td>
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<tr><td width=20><td><b>VAC(1)</b><td align=right><b>VAC(1)</b>
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<tr><td width=20><td colspan=2>
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<br>
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<p><font size=+1><b>NAME </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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vac – create a vac archive on Venti<br>
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</table>
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<p><font size=+1><b>SYNOPSIS </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>vac</font></tt> [ <tt><font size=+1>−mqsv</font></tt> ] [ <tt><font size=+1>−b</font></tt> <i>blocksize</i> ] [ <tt><font size=+1>−d</font></tt> <i>oldvacfile</i> ] [ <tt><font size=+1>−e</font></tt> <i>exclude</i>
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] [ <tt><font size=+1>−f</font></tt> <i>vacfile</i> ] [ <tt><font size=+1>−i</font></tt> <i>name</i> ] [ <tt><font size=+1>−h</font></tt> <i>host</i> ] <i>file ...<br>
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</i>
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</table>
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<p><font size=+1><b>DESCRIPTION </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<i>Vac</i> creates an archival copy of Plan 9 file trees on Venti. It
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can be used to build a simple backup system. One of the unusual
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properties of Venti is that duplicate blocks are detected and
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coalesced. When <i>vac</i> is used on a file tree that shares data with
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an existing archive, the consumption of storage will be approximately
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equal to an incremental backup. This reduction in storage consumption
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occurs transparently to the user.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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As an optimization, the <tt><font size=+1>−d</font></tt> and <tt><font size=+1>−q</font></tt> options, described below, can
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be used to explicitly create an archive relative to an existing
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archive. These options do not change the resulting archive generated
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by <i>vac</i>, but simply reduce the number of write operations to Venti.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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The output of <i>vac</i> is the hexadecimal representation of the Sha1
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fingerprint of the root of the archive, in this format:<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>vac:64daefaecc4df4b5cb48a368b361ef56012a4f46<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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</font></tt>
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</table>
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Option to <i>vac</i> are:<br>
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<tt><font size=+1>−b</font></tt> <i>blocksize<br>
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</i>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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Specifies the block size that data will be broken into. The units
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for the size can be specified by appending <tt><font size=+1>k</font></tt> to indicate kilobytes.
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The default is 8k. The size must be in the range of 512 bytes
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to 52k.<br>
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</table>
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<tt><font size=+1>−d</font></tt> <i>oldvacfile<br>
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</i>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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Reduce the number of blocks written to Venti by comparing the
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files to be stored with the contents of an existing <i>vac</i> file tree
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given by <i>oldvacfile</i>.<br>
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</table>
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<tt><font size=+1>−e</font></tt> <i>exclude<br>
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</i>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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Do not include the file or directory specified by <i>exclude</i>. This
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option may be repeated multiple times.<br>
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</table>
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<tt><font size=+1>−f</font></tt> <i>vacfile<br>
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</i>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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The results of <i>vac</i> are place in <i>vacfile</i>, or the standard output
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if no file is given.<br>
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</table>
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<tt><font size=+1>−i</font></tt> <i>name<br>
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</i>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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Include standard input as one of the input files, storing it in
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the archive with the specified <i>name</i>.<br>
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</table>
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<tt><font size=+1>−h</font></tt> <i>host<br>
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</i>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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The network address of the Venti server. The default is taken
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from the environment variable <tt><font size=+1>venti</font></tt>.<br>
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</table>
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<tt><font size=+1>−m</font></tt> Expand and merge any <i>vac</i> archives that are found while reading
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the input files. This option is useful for building an archive
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from a collection of existing archives. Each archive is inserted
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into the new archive as if it had been unpacked in the directory
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in which it was found. Multiple archives can be unpacked in
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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a single directory and the contents will be merged. To be detected,
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the archives must end in <tt><font size=+1>.vac</font></tt>. Note, an archive is inserted by
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simply copying the root fingerprint and does not require the archive
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to be unpacked.<br>
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</table>
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<tt><font size=+1>−q</font></tt> Increase the performance of the <tt><font size=+1>−d</font></tt> option by detecting unchanged
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files based on a match of the files name and other meta data,
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rather than examining the contents of the files.<br>
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<tt><font size=+1>−s</font></tt> Print out various statistics on standard error.<br>
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<tt><font size=+1>−v</font></tt> Produce more verbose output on standard error, including the
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name of the files added to the archive and the vac archives that
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are expanded and merged.<br>
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</table>
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<p><font size=+1><b>SOURCE </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>/usr/local/plan9/src/cmd/vac<br>
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</font></tt>
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</table>
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<p><font size=+1><b>SEE ALSO </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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Plan 9’s <i>vacfs</i>(4) and <i>venti</i>(8)<br>
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</table>
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<td width=20>
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<tr height=20><td>
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</table>
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<!-- TRAILER -->
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<table border=0 cellpadding=0 cellspacing=0 width=100%>
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<tr height=15><td width=10><td><td width=10>
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<tr><td><td>
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<center>
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<a href="../../"><img src="../../dist/spaceglenda100.png" alt="Space Glenda" border=1></a>
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</center>
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</table>
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<!-- TRAILER -->
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</body></html>
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