| 1 | .TH REMSYNC 1
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| 2 | .SH NAME
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| 3 | remsync - remotely synchronize file trees
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| 4 | .SH SYNOPSIS
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| 5 | .B remsync
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| 6 | .B \-sxv
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| 7 | .I tree
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| 8 | .RI [ state-file ]
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| 9 | .br
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| 10 | .B remsync
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| 11 | .B \-duxvD
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| 12 | .I tree
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| 13 | .RI [ state-file
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| 14 | .RI [ diff-file ]]
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| 15 | .br
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| 16 | .B remsync
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| 17 | .RB [ \-xv ]
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| 18 | .I tree
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| 19 | .RI [ diff-file ]
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| 20 | .SH DESCRIPTION
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| 21 | .de SP
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| 22 | .if t .sp 0.4
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| 23 | .if n .sp
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| 24 | ..
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| 25 | .B Remsync
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| 26 | synchronizes file trees of distant machines, i.e. machines that do not have
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| 27 | a fast network between them. It accomplishes this in three steps:
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| 28 | .PP
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| 29 | .RS
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| 30 | Create a state file containing a description of the machine to be updated.
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| 31 | .RE
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| 32 | .PP
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| 33 | .RS
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| 34 | Compute a file of differences on the source machine using the state file to
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| 35 | compare the two file trees.
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| 36 | .RE
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| 37 | .PP
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| 38 | .RS
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| 39 | Update the target machine using the data in the differences file.
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| 40 | .RE
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| 41 | .PP
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| 42 | This process requires that you move two files, a state file from the target
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| 43 | machine to the source machine, and a differences file from the source
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| 44 | machine to the target machine. The state file is an ASCII file that may be
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| 45 | edited, usually to make
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| 46 | .B remsync
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| 47 | ignore some files or file trees.
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| 48 | .PP
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| 49 | The argument
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| 50 | .I tree
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| 51 | may be a single file or a directory. A directory is traversed recursively.
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| 52 | The
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| 53 | .I state-file
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| 54 | and
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| 55 | .I diff-file
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| 56 | arguments may be of any file type. The differences file contains an end
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| 57 | marker, so it may be followed by trailing junk. Standard input or
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| 58 | output is used if these arguments are omitted or replaced by a minus
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| 59 | sign.
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| 60 | .SS "State file format"
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| 61 | A state file has a line for each file in a tree. A line looks like this
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| 62 | formally for a simple file:
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| 63 | .PP
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| 64 | .RS
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| 65 | .I "name mode owner group length date"
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| 66 | .RI [ link-number
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| 67 | .RB [ last ]]
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| 68 | .RE
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| 69 | .PP
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| 70 | The best way to show how each type of file is represented is by example:
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| 71 | .PP
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| 72 | .RS
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| 73 | .nf
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| 74 | .ta +10 +8 +4 +4 +6 +12 +4
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| 75 | / d755 0 0
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| 76 | bin d755 2 0
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| 77 | .in +2
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| 78 | [ 644 2 0 233 759160857 1
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| 79 | cat 755 2 0 3772 768742021
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| 80 | test 755 2 0 233 759160857 1 last
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| 81 | .in -2
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| 82 | dev d755 0 0
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| 83 | .in +2
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| 84 | fd0 b666 0 0 200
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| 85 | console c600 10 0 400
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| 86 | sd2 b600 0 0 a02
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| 87 | fifo p700 2 0
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| 88 | .in -2
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| 89 | opt -> usr/opt
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| 90 | usr ignore (Cross-device link)
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| 91 | .fi
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| 92 | .RE
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| 93 | .PP
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| 94 | The root of the tree is always represented by a /, no matter what type of
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| 95 | file it may be. Directory entries of the root follow at the same level.
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| 96 | Files in subdirectories are indented by two spaces. (Eight spaces are
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| 97 | replaced by a TAB.) Normal files have their length and modified time in the
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| 98 | state file, devices have their device number in hex, etc. If files are hard
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| 99 | linked to each other then they all get an extra "link number" to bind them
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| 100 | together. The last link is marked with the word
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| 101 | .BR last .
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| 102 | .PP
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| 103 | One usually only modifies a state file to ignore differences between two
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| 104 | files. One does this by replacing the file attributes with the word
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| 105 | .BR ignore .
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| 106 | .RB ( Remsync
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| 107 | generates this keyword too, with the reason why added in parentheses.)
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| 108 | .SH OPTIONS
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| 109 | .TP
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| 110 | .B \-s
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| 111 | Generate a state file.
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| 112 | .TP
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| 113 | .B \-d
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| 114 | Generate a differences file. (The default is to apply a differences file.)
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| 115 | .TP
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| 116 | .B \-u
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| 117 | Only add new files or update files with newer versions.
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| 118 | .TP
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| 119 | .B \-x
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| 120 | Do not cross device boundaries. This allows one to operate on the root file
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| 121 | system for instance ignoring the
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| 122 | .B /usr
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| 123 | file system.
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| 124 | .TP
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| 125 | .B \-D
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| 126 | Debug differences file generation. With this flag no file contents are
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| 127 | added to the differences file. The result is then human readable.
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| 128 | .TP
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| 129 | .B \-v
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| 130 | Lists the commands added to the differences file, or the actions done
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| 131 | applying a differences file. The output looks like \s-2UNIX\s+2 commands
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| 132 | except for the words "add", "restore" and "update" indicating addition of a
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| 133 | new file, replacing a file with an older version, or replacement by a newer
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| 134 | version.
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| 135 | .SH EXAMPLES
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| 136 | Actions taken by the author to update his notebook "finiah" from his main
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| 137 | machine "darask":
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| 138 | .PP
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| 139 | .RS
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| 140 | .nf
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| 141 | finiah# remsync -s /usr /tmp/finiah.state
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| 142 | .SP
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| 143 | Edit the state file to ignore .Xauthority files and /usr/var.
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| 144 | .SP
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| 145 | finiah# tar cvf /dev/fd0 /tmp/finiah.state
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| 146 | .SP
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| 147 | darask# tar xvf /dev/fd0
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| 148 | .br
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| 149 | darask# remsync -dv /usr /tmp/finiah.state | vol 1440 /dev/fd0
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| 150 | .SP
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| 151 | finiah# vol 1440 /dev/fd0 | remsync -v /usr
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| 152 | .fi
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| 153 | .RE
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| 154 | .PP
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| 155 | One could add a file compression/decompression program between
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| 156 | .B remsync
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| 157 | and
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| 158 | .BR vol ,
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| 159 | to reduce the number of floppies to move about, but that actually slows
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| 160 | things down! (Note that one only needs to shuffle two floppies about if the
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| 161 | two machines are adjacent. To update a remote machine it does make sense to
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| 162 | use compression to reduce the number of floppies to carry.)
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| 163 | .SH "SEE ALSO"
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| 164 | .BR synctree (1),
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| 165 | .BR vol (1),
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| 166 | .BR tar (1).
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| 167 | .SH NOTES
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| 168 | Nothing stops you from using
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| 169 | .B remsync
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| 170 | over a fast network of course.
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| 171 | .B Synctree
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| 172 | can be a bit tedious if you only want to ignore a few files. Editing a
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| 173 | state file is then easier.
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| 174 | .SH BUGS
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| 175 | Files are overwritten, not removed, when they are updated. This means
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| 176 | that links outside the tree are also updated. The less desirable
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| 177 | alternative to this is to break the link before the update.
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| 178 | .PP
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| 179 | The verbose option may say that a link is to be created when making a
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| 180 | differences file. The link is often already there when the update takes
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| 181 | place, so no action is taken, and thus no talk about it. So you may miss a
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| 182 | few mutterings about links if you compare the messages.
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| 183 | .SH AUTHOR
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| 184 | Kees J. Bot (kjb@cs.vu.nl)
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