Rsync+crontab regular synchronization backup under centos7

[root@localhost ~]# mkdir rsyncd
[root@localhost ~]# vim /rsyncd/rsyncd.pass
[root@localhost ~]# chmod 600 /rsyncd/rsyncd.pass

rsync -arvz --progress /data [email protected]::log --password-file=/rsyncd/rsyncd.pass

#Pull the entire directory rsync -arvz --progress --password-file=/rsyncd/rsyncd.pass --port=873 [email protected]::log /var/log
#Pull a single file rsync -arvz --progress --password-file=/rsyncd/rsyncd.pass --port=873 [email protected]::log/a.log /var/log

All parameters before [module] in the file are global parameters. Of course, you can also define module parameters in the global parameter part. In this case, the value of the parameter is the default value for all modules.
port
Specifies the port number used by the background program. The default is 873.
motd file
The "motd file" parameter is used to specify a message file. The contents of this file are displayed to the client when it connects to the server. By default, there is no motd file.
log file
"log file" specifies the log file for rsync instead of sending the log to syslog. For example, it can be specified as "/var/log/rsyncd.log".
pid file
Specify the rsync pid file, usually specified as "/var/run/rsyncd.pid".
syslog facility
Specifies the message level at which rsync sends log messages to syslog. Common message levels are: uth, authpriv, cron, daemon, ftp, kern, lpr, mail, news, security, sys-log, user, uucp, local0, local1, local2, local3, local4, local5, local6, and local7. The default value is daemon.
The module parameters mainly define which directory of the server should be synchronized. The format must be "[module]". This name is the name seen on the rsync client, which is actually a bit like the share name provided by the Samba server. The data that the server actually synchronizes is specified by path. We can specify multiple modules according to our needs. The following parameters can be defined in the module:
comment
Assign a description to the module, which is displayed along with the module name to clients when they connect to get a list of modules. By default no description is defined.
path
Specifies the directory tree path for backup of this module. This parameter is required.
use chroot
If "use chroot" is specified as true, rsync will first chroot to the directory specified by the path parameter before transferring files. The reason for doing this is to achieve additional security protection, but the disadvantage is that it requires root permissions and cannot back up directory files pointed to by external symbolic links. By default the chroot value is true.
uid
This option specifies the uid that the daemon should have when the module transfers files. Used with the gid option, it can determine what file permissions can be accessed. The default value is "nobody".
gid
This option specifies the gid that the daemon should have when this module transfers files. The default value is "nobody".
max connections
Specify the maximum number of concurrent connections for this module to protect the server. Connection requests exceeding the limit will be notified and tried again later. The default value is 0, which means no limit.
list
This option specifies whether this module should be listed when a client requests a list of available modules. If you set this option to false, hidden modules can be created. The default value is true.
read only
This option determines whether clients are allowed to upload files. If true then any upload request will fail, if false and the server directory read and write permissions allow then the upload is allowed. The default value is true.
exclude
Used to specify multiple files or directories (relative paths) separated by spaces and add them to the exclude list. This is equivalent to using --exclude to specify the pattern in the client command. Only one exclude option can be specified for a module. However, one thing to note is that this option has certain security issues. Customers are likely to bypass the exclude list. If you want to ensure that specific files cannot be accessed, it is best to use it in conjunction with the uid/gid option.
exclude from
Specifies a file name containing the definition of exclude patterns. The server reads the exclude list definition from this file.
include
Used to specify that files or directories that meet the requirements are not excluded. This is equivalent to using --include in the client command to specify the pattern. Combining include and exclude can define complex exclude/include rules.
include from
Specifies a file name containing the definition of include patterns. The server reads the include list definition from this file.
auth users
This option specifies a space or comma separated list of usernames that are allowed to connect to this module. The users here have nothing to do with system users. If "auth users" is set, then the client's connection request to the module will be challenged by rsync for identity verification. The challenge/response authentication protocol used here. The user's name and password are stored in plain text in the file specified by the "secrets file" option. By default, you can connect to the module without a password (that is, anonymously).
secrets file
This option specifies a file containing defined username:password pairs. This file only has effect if "auth users" is defined. Each line of the file contains one username:passwd pair. Generally speaking, the password should not exceed 8 characters. There is no default secures file name, you need to specify one (for example: /etc/rsyncd.passwd). Note: The file permission must be 600, otherwise the client will not be able to connect to the server.
strict modes
This option specifies whether to monitor the permissions of the password file. If the option value is true, the password file can only be accessed by the user who runs the rsync server, and no other user can access the file. The default value is true.
hosts allow
This option specifies which IP clients are allowed to connect to this module. A customer schema definition can be of the following form:
A single IP address, for example: 192.167.0.1
The entire network segment, for example: 192.168.0.0/24, or 192.168.0.0/255.255.255.0
Multiple IPs or network segments need to be separated by spaces, and "*" means all. By default, all hosts are allowed to connect.
hosts deny
To specify machines that are not allowed to connect to the rsync server, you can use the hosts allow definition method to define them. By default, there is no hosts deny definition.
ignore errors
Specifies that rsyncd ignore IO errors on the server when determining whether to run the delete operation during transmission. Generally, rsync will skip the --delete operation when an IO error occurs to prevent serious problems caused by temporary resource shortages or other IO errors.
ignore nonreadable
Specifies that the rysnc server completely ignores files to which the user does not have access permissions. This makes sense in situations where there are files in the directory being backed up that should not be accessible to the backup recipient.
lock file
Specifies the lock file that supports the max connections parameter. The default value is /var/run/rsyncd.lock.
transfer logging
Causes the rsync server to log download and upload operations in their own separate log using ftp-formatted files.
log format
With this option, users can customize the fields of the log file when using transfer logging. Its format is a string containing format specifiers. The available format specifiers are as follows:
%h remote host name %a remote IP address %l file length in characters %p process id of this rsync session
%o Operation type: "send" or "recv"
%f file name %P module path %m module name %t current time %u authenticated user name (null for anonymous)
%b The actual number of bytes transferred %c When sending a file, this field records the checksum of the file. The default log format is: "%o %h [%a] %m (%u) %f %l". Generally speaking, "%t [%p] " is added to the header of each line. Also released in the source code is a perl script called rsyncstats to count log files in this format.
timeout
This option can be used to override the customer-specified IP timeout period. This option ensures that the rsync server does not wait forever for a crashed client. The timeout unit is seconds. 0 means no timeout is defined, which is also the default value. For an anonymous rsync server, a good number is 600.
refuse options
This option can be used to define a list of command parameters that clients are not allowed to use for this module. The full command name must be used here, not the abbreviation. However, if a command is rejected, the server will report an error message and exit. To prevent compression from being used, it should be: "dont compress = *".
don't compress
Used to specify files that are not compressed and transferred. The default value is *.gz *.tgz *.zip *.z *.rpm *.deb *.iso *.bz2 *.tbz

-v, --verbose Verbose output mode -q, --quiet Concise output mode -c, --checksum Turn on the checksum switch to force verification of file transfers -a, --archive Archive mode, which means transferring files recursively and keeping all file attributes, which is equal to -rlptgoD
 -r, --recursive Process subdirectories in recursive mode -R, --relative Use relative path information -b, --backup Create a backup, that is, when the same file name already exists for the destination, rename the old file to ~filename. You can use the --suffix option to specify a different backup file prefix.
 --backup-dir Store the backup file (such as ~filename) in the directory.
 -suffix=SUFFIX defines the backup file prefix -u, --update only updates, that is, skips all files that already exist in DST and whose file time is later than the files to be backed up. (Do not overwrite updated files)
 : : : : : : : : : : : : : : :
 -T --temp-dir=DIR Create temporary files in DIR --compare-dest=DIR Also compare the files in DIR to determine whether they need to be backed up -P Equivalent to --partial
 --progress Display the backup process -z, --compress Compress the backed-up files during transmission --exclude=PATTERN Specify the file pattern that does not need to be transferred --include=PATTERN Specify the file pattern that needs to be transferred but is not excluded --exclude-from=FILE Exclude files with the specified pattern in FILE --include-from=FILE Do not exclude files that match the specified pattern in FILE --version Print version information --address Bind to a specific address --config=FILE Specify other configuration files, do not use the default rsyncd.conf file --port=PORT Specify other rsync service ports --blocking-io Use blocking IO for remote shell
 -stats gives the transfer status of some files --progress shows the transfer progress during the transfer --log-format=formAT specifies the log file format --password-file=FILE gets the password from FILE --bwlimit=KBPS limits the I/O bandwidth to KBytes per second
 -h, --help Display help information

Crond is a daemon process used in Linux to periodically execute certain tasks or wait for certain events to be processed. It is similar to the scheduled tasks in Windows. When the operating system is installed, this service tool will be installed by default and the crond process will be automatically started. The crond process will periodically check every minute whether there are tasks to be executed. If there are tasks to be executed, the task will be automatically executed.
Task scheduling under Linux is divided into two categories: system task scheduling and user task scheduling.
System task scheduling: The work that the system needs to perform periodically, such as writing cache data to the hard disk, cleaning up logs, etc. There is a crontab file in the /etc directory, which is the configuration file for system task scheduling.
The /etc/crontab file contains the following lines:

[root@localhost ~]# cat /etc/crontab
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=""HOME=/

# run-parts
51 * * * * root run-parts /etc/cron.hourly
24 7 * * * root run-parts /etc/cron.daily
22 4 * * 0 root run-parts /etc/cron.weekly
42 4 1 * * root run-parts /etc/cron.monthly

 [root@localhost ~]# crontab -l
 0,15,30,45,18-06 * * * /bin/echo `date` > dev/tty

 [root@localhost ~]# crontab -l > $HOME/mycron

[root@localhost ~]# crontab -e

# DT: delete core files, at 3.30am on 1, 7, 14, 21, 26, 26 days of each month (comments)

 30 3 1,7,14,21,26 * * /bin/find -name "core' -exec rm {} \;

[root@localhost ~]# crontab -l 
 # (crondave installed on Tue May 4 13:07:43 1999)
 # DT:ech the date to the console every 30 minutes
 0,15,30,45 18-06 * * * /bin/echo `date` > /dev/tty1
 # DT: delete core files, at 3.30am on 1, 7, 14, 21, 26, 26 days of each month
 30 3 1,7,14,21,26 * * /bin/find -name "core' -exec rm {} \;

 [root@localhost ~]# crontab -r

[root@localhost ~]# crontab -e
# DT:Execute rsync-sh script every Sunday at 00: 00 (comments)
0 0 * * 7 sh /root/rsyncd/rsync-gitbak.sh

[root@localhost rsyncd]# vim rsyncd.sh
#!/bin/bash
rsync -arvz --progress /data [email protected]::log --password-file=/rsyncd/rsyncd.pass

[root@localhost ~]# crontab -e
# DT:Execute rsync-sh script every Sunday at 00: 00 (comments)
0 0 * * 7 sh /root/rsyncd/rsyncd.sh

[root@localhost ~]# crontab -l
0 0 * * 7 sh /root/rsyncd/rsyncd.sh