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4 <TITLE>rsync FAQ</TITLE>
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8 <H2 align="center">Frequently Asked Questions</H2>
10 <table><tr valign=top><td><ul>
11 <li><a href="#1">the transfer fails to finish</a><br>
12 <li><a href="#2">copies every file</a><br>
13 <li><a href="#3">is your shell clean</a><br>
14 <li><a href="#4">memory usage</a><br>
15 <li><a href="#5">out of memory</a><br>
16 <li><a href="#6">rsync through a firewall</a><br>
17 </ul></td><td> </td><td><ul>
18 <li><a href="#7">rsync and cron</a><br>
19 <li><a href="#8">rsync: Command not found</a><br>
20 <li><a href="#9">spaces in filenames</a><br>
21 <li><a href="#10">ignore "vanished files" warning</a><br>
22 <li><a href="#11">read-only file system</a><br>
23 </ul></td></tr></table>
26 <h3><a name=1>the transfer fails to finish</a></h3>
28 <p>If you get an error like one of these:
30 <pre>rsync: error writing 4 unbuffered bytes - exiting: Broken pipe
31 rsync error: error in rsync protocol data stream (code 12) at io.c(463)
36 <pre>rsync: connection unexpectedly closed (24 bytes read so far)
37 rsync error: error in rsync protocol data stream (code 12) at io.c(342)
40 <p>please read the <a href="issues.html">issues and debugging page</a>
41 for details on how you can try to figure out what is going wrong.
44 <h3><a name=2>copies every file</a></h3>
46 <p>Some people occasionally report that rsync copies every file when they
47 expect it to copy only a small subset. In most cases the explanation is
48 that you forgot to include the --times (-t) option in the original copy,
49 so rsync is forced to (efficiently) transfer every file to see if it has
50 changed (because the modified time and size do not match).
52 <p>Another common cause involves sending files to an Microsoft filesystem:
53 if the file's modified time is an odd value but the receiving filesystem
54 can only even values, then rsync will re-transfer too many files. You can
55 avoid this by specifying the --modify-window=1 option.
57 <p>If you think that rsync is erroneously copying every file then look at
58 the stats produced with -v and see if rsync is really sending all the data.
59 See also the --checksum (-c) option for one way to avoid the extra copying
60 without synchronizing the modified times.
63 <h3><a name=3>is your shell clean</a></h3>
65 <p>The "is your shell clean" message and the "protocol mismatch" message
66 are usually caused by having some sort of program in your .cshrc, .profile,
67 .bashrc or equivalent file that writes a message every time you connect
68 using a remote-shell program (such as ssh or rsh). Data written in this
69 way corrupts the rsync data stream. rsync detects this at startup and
70 produces those error messages. However, if you are using rsync-daemon
71 syntax (host::path or rsync://) without using a remote-shell program (no
72 --rsh or -e option), there is not remote-shell program involved, and the
73 problem is probably caused by an error on the daemon side (so check the
76 <p>A good way to test if your remote-shell connection is clean is to try
77 something like this (use ssh or rsh, as appropriate):
79 <blockquote><pre>ssh remotesystem /bin/true > test.dat</pre></blockquote>
81 <p>That should create a file called test.dat with nothing in it. If
82 test.dat is not of zero length then your shell is not clean. Look at the
83 contents of test.dat to see what was sent. Look at all the startup files on
84 remotesystem to try and find the problem.
87 <h3><a name=4>memory usage</a></h3>
89 <p>Yes, rsync uses a lot of memory. The majority of the memory is used to
90 hold the list of files being transferred. This takes about 100 bytes per
91 file, so if you are transferring 800,000 files then rsync will consume
92 about 80M of memory. It will be higher if you use -H or --delete.
94 <p>To fix this requires a major rewrite of rsync, which my or may not
98 <h3><a name=5>out of memory</a></h3>
100 <p>The usual reason for "out of memory" when running rsync is that you are
101 transferring a _very_ large number of files. The size of the files doesn't
102 matter, only the total number of files.
104 <p>As a rule of thumb you should expect rsync to consume about 100 bytes
105 per file in the file list. This happens because rsync builds a internal
106 file list structure containing all the vital details of each file. rsync
107 needs to hold structure in memory because it is being constantly traversed.
109 <p>A future version of rsync could be built with an improved protocol that
110 transfers files in a more incremental fashion, which would require a lot
111 less memory. Unfortunately, such an rsync does not yet exist.
114 <h3><a name=6>rsync through a firewall</a></h3>
116 <p>If you have a setup where there is no way to directly connect two
117 systems for an rsync transfer, there are several ways to get a firewall
118 system to act as an intermediary in the transfer. You'll find full details
119 on the <a href="firewall.html">firewall methods</a> page.
122 <h3><a name=7>rsync and cron</a></h3>
124 <p>On some systems (notably SunOS4) cron supplies what looks like a socket
125 to rsync, so rsync thinks that stdin is a socket. This means that if you
126 start rsync with the --daemon switch from a cron job you end up rsync
127 thinking it has been started from inetd. The fix is simple—just
128 redirect stdin from /dev/null in your cron job.
131 <h3><a name=8>rsync: Command not found</a></h3>
133 <p>This error is produced when the remote shell is unable to locate the rsync
134 binary in your path. There are 3 possible solutions:
138 <li>install rsync in a "standard" location that is in your remote path.
140 <li>modify your .cshrc, .bashrc etc on the remote system to include the path
143 <li>use the --rsync-path option to explicitly specify the path on the
144 remote system where rsync is installed
148 <p>You may echo find the command:
150 <blockquote><pre>ssh host 'echo $PATH'</pre></blockquote>
152 <p>for determining what your remote path is.
155 <h3><a name=9>spaces in filenames</a></h3>
157 <p>Can rsync copy files with spaces in them?
159 <p>Short answer: Yes, rsync can handle filenames with spaces.
163 <p>Rsync handles spaces just like any other unix command line application.
164 Within the code spaces are treated just like any other character so a
165 filename with a space is no different from a filename with any other
168 <p>The problem of spaces is in the argv processing done to interpret the
169 command line. As with any other unix application you have to escape spaces
170 in some way on the command line or they will be used to separate arguments.
172 <p>It is slightly trickier in rsync (and other remote-copy programs like
173 scp) because rsync sends a command line to the remote system to launch the
174 peer copy of rsync (this assumes that we're not talking about daemon mode,
175 which is not affected by this problem because no remote shell is involved
176 in the reception of the filenames). The command line is interpreted by the
177 remote shell and thus the spaces need to arrive on the remote system
178 escaped so that the shell doesn't split such filenames into multiple
183 <blockquote><pre>rsync -av host:'a long filename' /tmp/</pre></blockquote>
185 <p>This is usually a request for rsync to copy 3 files from the remote
186 system, "a", "long", and "filename" (the only exception to this is for a
187 system running a shell that does not word-split arguments in its commands,
188 and that is exceedingly rare). If you wanted to request a single file with
189 spaces, you need to get some kind of space-quoting characters to the remote
190 shell that is running the remote rsync command. The following commands
193 <blockquote><pre>rsync -av host:'"a long filename"' /tmp/
194 rsync -av host:'a\ long\ filename' /tmp/
195 rsync -av host:a\\\ long\\\ filename /tmp/</pre></blockquote>
197 <p>You might also like to use a '?' in place of a space as long as there
198 are no other matching filenames than the one with spaces (since '?' matches
201 <blockquote><pre>rsync -av host:a?long?filename /tmp/</pre></blockquote>
203 <p>As long as you know that the remote filenames on the command line
204 are interpreted by the remote shell then it all works fine.
207 <h3><a name=10>ignore "vanished files" warning</a></h3>
209 <p>Some folks would like to ignore the "vanished files" warning, which
210 manifests as an exit-code 24. The easiest way to do this is to create
211 a shell script wrapper. For instance, name this something like
214 <blockquote><pre>#!/bin/sh
217 if test $e = 24; then
220 exit $e</pre></blockquote>
223 <h3><a name=11>read-only file system</a></h3>
225 <p>If you get "Read-only file system" as an error when sending to a rsync
226 daemon then you probably forgot to set "read only = no" for that module.
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