一、介绍

rsync命令是一个远程数据同步工具，可以通过LAN/WAN快速同步多台主机间的文件。rsync使用所谓的“rsync算法”来使本地和远程两个主机之间的文件达到同步，这个算法只传送两个文件的不同部分，而不是每次都整份传送，因此速度相当快。

• rsync功能
  • 作为命令，实现本地-远程文件同步
  • 作为服务，实现本地-远程文件同步
• rsync特点
  • 可以镜像保存整个目录树和文件系统
  • 可以保留原有文件的权限（permission,mode）、owner、group、时间（创建时间，modify time）、软硬链接、文件acl、文件属性（attributes）信息等；
  • 传输效率高，使用同步算法，之比较变化文件；
  • 支持匿名传输，方便网站镜像；也可以做验证，加强安全；
• rsync同类服务
  • sync同步：刷新文件系统缓存，强制将修改过的数据块写入磁盘，并且更新超级块；
  • async异步：将数据先放到缓冲区，再周期性（一般是30S）的去同步磁盘；
  • rsync远程同步：remote synchronous；

rsync工具官网：http://rsync.samba.org/

比较好的博客：https://blog.csdn.net/jiangyu1013/article/details/79754060

在CentOS7系统上运行下面命令即可安装rsync命令支持。

sudo yum install rsync

在Linux系统上运行如下命令可查看rsync命令的详细文档：

man 1 rsync

在Linux系统上运行如下命令可查看rsyncd.conf配置文件的详细文档：

man 5 rsyncd.conf

二、rsync命令格式

Local:  rsync [OPTION...] SRC... [DEST]

Access via remote shell:
 Pull: rsync [OPTION...] [USER@]HOST:SRC... [DEST]
 Push: rsync [OPTION...] SRC... [USER@]HOST:DEST

Access via rsync daemon:
 Pull: rsync [OPTION...] [USER@]HOST::SRC... [DEST]
       rsync [OPTION...] rsync://[USER@]HOST[:PORT]/SRC... [DEST]
 Push: rsync [OPTION...] SRC... [USER@]HOST::DEST
       rsync [OPTION...] SRC... rsync://[USER@]HOST[:PORT]/DEST

Usages with just one SRC arg and no DEST arg will list the source files instead of copying.

三、rsync常用选项

 -v, --verbose               increase verbosity
     --info=FLAGS            fine-grained informational verbosity
     --debug=FLAGS           fine-grained debug verbosity
     --msgs2stderr           special output handling for debugging
 -q, --quiet                 suppress non-error messages
     --no-motd               suppress daemon-mode MOTD (see manpage caveat)
 -c, --checksum              skip based on checksum, not mod-time & size
 -a, --archive               archive mode; equals -rlptgoD (no -H,-A,-X)
     --no-OPTION             turn off an implied OPTION (e.g. --no-D)
 -r, --recursive             recurse into directories
 -R, --relative              use relative path names
     --no-implied-dirs       don't send implied dirs with --relative
 -b, --backup                make backups (see --suffix & --backup-dir)
     --backup-dir=DIR        make backups into hierarchy based in DIR
     --suffix=SUFFIX         set backup suffix (default ~ w/o --backup-dir)
 -u, --update                skip files that are newer on the receiver
     --inplace               update destination files in-place (SEE MAN PAGE)
     --append                append data onto shorter files
     --append-verify         like --append, but with old data in file checksum
 -d, --dirs                  transfer directories without recursing
 -l, --links                 copy symlinks as symlinks
 -L, --copy-links            transform symlink into referent file/dir
     --copy-unsafe-links     only "unsafe" symlinks are transformed
     --safe-links            ignore symlinks that point outside the source tree
     --munge-links           munge symlinks to make them safer (but unusable)
 -k, --copy-dirlinks         transform symlink to a dir into referent dir
 -K, --keep-dirlinks         treat symlinked dir on receiver as dir
 -H, --hard-links            preserve hard links
 -p, --perms                 preserve permissions
 -E, --executability         preserve the file's executability
     --chmod=CHMOD           affect file and/or directory permissions
 -A, --acls                  preserve ACLs (implies --perms)
 -X, --xattrs                preserve extended attributes
 -o, --owner                 preserve owner (super-user only)
 -g, --group                 preserve group
     --devices               preserve device files (super-user only)
     --copy-devices          copy device contents as regular file
     --specials              preserve special files
 -D                          same as --devices --specials
 -t, --times                 preserve modification times
 -O, --omit-dir-times        omit directories from --times
 -J, --omit-link-times       omit symlinks from --times
     --super                 receiver attempts super-user activities
     --fake-super            store/recover privileged attrs using xattrs
 -S, --sparse                handle sparse files efficiently
     --preallocate           allocate dest files before writing them
 -n, --dry-run               perform a trial run with no changes made
 -W, --whole-file            copy files whole (without delta-xfer algorithm)
 -x, --one-file-system       don't cross filesystem boundaries
 -B, --block-size=SIZE       force a fixed checksum block-size
 -e, --rsh=COMMAND           specify the remote shell to use
     --rsync-path=PROGRAM    specify the rsync to run on the remote machine
     --existing              skip creating new files on receiver
     --ignore-existing       skip updating files that already exist on receiver
     --remove-source-files   sender removes synchronized files (non-dirs)
     --del                   an alias for --delete-during
     --delete                delete extraneous files from destination dirs
     --delete-before         receiver deletes before transfer, not during
     --delete-during         receiver deletes during the transfer
     --delete-delay          find deletions during, delete after
     --delete-after          receiver deletes after transfer, not during
     --delete-excluded       also delete excluded files from destination dirs
     --ignore-missing-args   ignore missing source args without error
     --delete-missing-args   delete missing source args from destination
     --ignore-errors         delete even if there are I/O errors
     --force                 force deletion of directories even if not empty
     --max-delete=NUM        don't delete more than NUM files
     --max-size=SIZE         don't transfer any file larger than SIZE
     --min-size=SIZE         don't transfer any file smaller than SIZE
     --partial               keep partially transferred files
     --partial-dir=DIR       put a partially transferred file into DIR
     --delay-updates         put all updated files into place at transfer's end
 -m, --prune-empty-dirs      prune empty directory chains from the file-list
     --numeric-ids           don't map uid/gid values by user/group name
     --usermap=STRING        custom username mapping
     --groupmap=STRING       custom groupname mapping
     --chown=USER:GROUP      simple username/groupname mapping
     --timeout=SECONDS       set I/O timeout in seconds
     --contimeout=SECONDS    set daemon connection timeout in seconds
 -I, --ignore-times          don't skip files that match in size and mod-time
 -M, --remote-option=OPTION  send OPTION to the remote side only
     --size-only             skip files that match in size
     --modify-window=NUM     compare mod-times with reduced accuracy
 -T, --temp-dir=DIR          create temporary files in directory DIR
 -y, --fuzzy                 find similar file for basis if no dest file
     --compare-dest=DIR      also compare destination files relative to DIR
     --copy-dest=DIR         ... and include copies of unchanged files
     --link-dest=DIR         hardlink to files in DIR when unchanged
 -z, --compress              compress file data during the transfer
     --compress-level=NUM    explicitly set compression level
     --skip-compress=LIST    skip compressing files with a suffix in LIST
 -C, --cvs-exclude           auto-ignore files the same way CVS does
 -f, --filter=RULE           add a file-filtering RULE
 -F                          same as --filter='dir-merge /.rsync-filter'
                             repeated: --filter='- .rsync-filter'
     --exclude=PATTERN       exclude files matching PATTERN
     --exclude-from=FILE     read exclude patterns from FILE
     --include=PATTERN       don't exclude files matching PATTERN
     --include-from=FILE     read include patterns from FILE
     --files-from=FILE       read list of source-file names from FILE
 -0, --from0                 all *-from/filter files are delimited by 0s
 -s, --protect-args          no space-splitting; only wildcard special-chars
     --address=ADDRESS       bind address for outgoing socket to daemon
     --port=PORT             specify double-colon alternate port number
     --sockopts=OPTIONS      specify custom TCP options
     --blocking-io           use blocking I/O for the remote shell
     --stats                 give some file-transfer stats
 -8, --8-bit-output          leave high-bit chars unescaped in output
 -h, --human-readable        output numbers in a human-readable format
     --progress              show progress during transfer
 -P                          same as --partial --progress
 -i, --itemize-changes       output a change-summary for all updates
     --out-format=FORMAT     output updates using the specified FORMAT
     --log-file=FILE         log what we're doing to the specified FILE
     --log-file-format=FMT   log updates using the specified FMT
     --password-file=FILE    read daemon-access password from FILE
     --list-only             list the files instead of copying them
     --bwlimit=RATE          limit socket I/O bandwidth
     --outbuf=N|L|B          set output buffering to None, Line, or Block
     --write-batch=FILE      write a batched update to FILE
     --only-write-batch=FILE like --write-batch but w/o updating destination
     --read-batch=FILE       read a batched update from FILE
     --protocol=NUM          force an older protocol version to be used
     --iconv=CONVERT_SPEC    request charset conversion of filenames
     --checksum-seed=NUM     set block/file checksum seed (advanced)
 -4, --ipv4                  prefer IPv4
 -6, --ipv6                  prefer IPv6
     --version               print version number
(-h) --help                  show this help (-h is --help only if used alone)

四、rsyncd.conf配置文件详解

• port：指定在哪个端口启动rsyncd服务，默认是873端口。
• log file：指定日志文件。
• pid file：指定pid文件，这个文件的作用涉及服务的启动、停止等进程管理操作。
• address：指定启动rsyncd服务的IP。假如你的机器有多个IP，就可以指定由其中一个启动rsyncd服务，如果不指定该参数，默认是在全部IP上启动。
• []：指定模块名，里面内容自定义。
• path：指定数据存放的路径。
• use chroot true|false：表示在传输文件前首先chroot到path参数所指定的目录下。这样做的原因是实现额外的安全防护，但缺点是需要以roots权限，并且不能备份指向外部的符号连接所指向的目录文件。默认情况下chroot值为true，如果你的数据当中有软连接文件，阿铭建议你设置成false。
• max connections：指定最大的连接数，默认是0，即没有限制。
• read only ture|false：如果为true，则不能上传到该模块指定的路径下。
• list：表示当用户查询该服务器上的可用模块时，该模块是否被列出，设定为true则列出，false则隐藏。
• uid/gid：指定传输文件时以哪个用户/组的身份传输。
• auth users：指定传输时要使用的用户名。
• secrets file：指定密码文件，该参数连同上面的参数如果不指定，则不使用密码验证。注意该密码文件的权限一定要是600。格式：用户名:密码
• hosts allow：表示被允许连接该模块的主机，可以是IP或者网段，如果是多个，中间用空格隔开。
• 当设置了auth users和secrets file后，客户端连服务端也需要用用户名密码了，若想在命令行中带上密码，可以设定一个密码文件
• rsync -avL test@192.168.36.130::test/test1/ /tmp/test8/ --password-file=/etc/pass
• 其中/etc/pass内容就是一个密码，权限要改为600

示例配置：

port=873
log file=/var/log/rsync.log
pid file=/var/run/rsyncd.pid
address=192.168.36.130
[test]
path=/tmp/rsync
use chroot=true
max connections=4
read only=no
list=true
uid=root
gid=root
auth users=test
secrets file=/etc/rsyncd.passwd
hosts allow=192.168.36.131 （多个ip以空格隔开，也可以写ip段：192.168.36.0/24）