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Brief

As we mentioned earlier, one-way synchronization uses rsync + inotify-tools. In some special usage scenarios, two-way synchronization may be required, which requires inotify-tools + unison.

Environmental preparation

  • Both Rocky Linux 8 and Fedora 34 require source code compilation and installation inotify-tools, which is not specifically expanded here.
  • Both machines must be password-free login authentication, here we use the SSH protocol for
  • ocaml uses v4.12.0, unison uses v2.51.4.

After the environment is ready, it can be verified:

[root@Rocky ~]# inotifywa
inotifywait inotifywatch
[root@Rocky ~]# ssh -p 22 testrsync@192.168.100.5
Last login: Thu Nov 4 13:13:42 2021 from 192.168.100.4
[testrsync@fedora ~]$

[root@fedora ~]# inotifywa
inotifywait inotifywatch
[root@fedora ~]# ssh -p 22 testrsync@192.168.100.4
Last login: Wed Nov 3 22:07:18 2021 from 192.168.100.5
[testrsync@Rocky ~]$

Attention

The configuration files of the two machines /etc/ssh/sshd_config should be opened PubkeyAuthentication yes

Rocky Linux 8 install unison

Ocaml is a programming language, and the bottom layer of unison depends on it.

[root@Rocky ~]# wget -c https://github.com/ocaml/ocaml/archive/refs/tags/4.12.0.tar.gz
[root@Rocky ~]# tar -zvxf 4.12.0.tar.gz -C /usr/local/src/
[root@Rocky ~]# cd /usr/local/src/ocaml-4.12.0
[root@Rocky /usr/local/src/ocaml-4.12.0]# ./configure --prefix=/usr/local/ocaml && make world opt && make install
...
[root@Rocky ~]# ls /usr/local/ocaml/
bin lib man
[root@Rocky ~]# echo PATH=$PATH:/usr/local/ocaml/bin >> /etc/profile
[root@Rocky ~]# . /etc/profile

[root@Rocky ~]# wget -c https://github.com/bcpierce00/unison/archive/refs/tags/v2.51.4.tar.gz
[root@Rocky ~]# tar -zvxf v2.51.4.tar.gz -C /usr/local/src/
[root@Rocky ~]# cd /usr/local/src/unison-2.51.4/
[root@Rocky /usr/local/src/unison-2.51.4]# make UISTYLE=txt
...
[root@Rocky /usr/local/src/unison-2.51.4]# ls src/unison
src/unison
[root@Rocky /usr/local/src/unison-2.51.4] cp -p src/unison /usr/local/bin

Fedora 34 install unison

The same operation.

[root@fedora ~]# wget -c https://github.com/ocaml/ocaml/archive/refs/tags/4.12.0.tar.gz
[root@feodora ~]# tar -zvxf 4.12.0.tar.gz -C /usr/local/src/
[root@fedora ~]# cd /usr/local/src/ocaml-4.12.0
[root@fedora /usr/local/src/ocaml-4.12.0]# ./configure --prefix=/usr/local/ocaml && make world opt && make install
...
[root@fedora ~]# ls /usr/local/ocaml/
bin lib man
[root@fedora ~]# echo PATH=$PATH:/usr/local/ocaml/bin >> /etc/profile
[root@fedora ~]#. /etc/profile

[root@fedora ~]# wget -c https://github.com/bcpierce00/unison/archive/refs/tags/v2.51.4.tar.gz
[root@fedora ~]# tar -zvxf v2.51.4.tar.gz -C /usr/local/src/
[root@fedora ~]# cd /usr/local/src/unison-2.51.4/
[root@fedora /usr/local/src/unison-2.51.4]# make UISTYLE=txt
...
[root@fedora /usr/local/src/unison-2.51.4]# ls src/unison
src/unison
[root@fedora /usr/local/src/unison-2.51.4]# cp -p src/unison /usr/local/bin

Demo

Our requirement is-Rocky Linux 8's /dir1/ directory is automatically synchronized to Fedora 34's /dir2/ directory; at the same time, Fedora 34's /dir2/ directory is automatically synchronized to Rocky Linux 8's /dir1/ directory

Configure Rcoky Linux 8

[root@Rocky ~]# mkdir /dir1
[root@Rocky ~]# setfacl -m u:testrsync:rwx /dir1/
[root@Rocky ~]# vim /root/unison1.sh
#!/bin/bash
a="/usr/local/inotify-tools/bin/inotifywait -mrq -e create,delete,modify,move /dir1/"
b="/usr/local/bin/unison -batch /dir1/ ssh://testrsync@192.168.100.5//dir2"
$a | while read directory event file
do
    $b &>> /tmp/unison1.log
done
[root@Rocky ~]# chmod +x /root/unison1.sh
[root@Rocky ~]# bash /root/unison1.sh &
[root@Rocky ~]# jobs -l

Configure Fedora 34

[root@fedora ~]# mkdir /dir2
[root@fedora ~]# setfacl -m u:testrsync:rwx /dir2/
[root@fedora ~]# vim /root/unison2.sh
#!/bin/bash
a="/usr/local/inotify-tools/bin/inotifywait -mrq -e create,delete,modify,move /dir2/"
b="/usr/local/bin/unison -batch /dir2/ ssh://testrsync@192.168.100.4//dir1"
$a | while read directory event file
do
    $b &>> /tmp/unison2.log
done
[root@fedora ~]# chmod +x /root/unison2.sh
[root@fedora ~]# bash /root/unison2.sh &
[root@fedora ~]# jobs -l

Attention!

For two-way synchronization, the scripts of both machines must be started, otherwise an error will be reported.

Attention!

If you want to start this script at boot [root@Rocky ~]# echo "bash /root/unison1.sh &" >> /etc/rc.local [root@Rocky ~]# chmod +x /etc/rc.local

Attention!

If you want to stop the corresponding process of this script, you can find it in the htop command and then kill

Last update: January 4, 2022

Author: tianci li

Contributors: Steven Spencer

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