1) rsync in linux
1@@@@ local @@@ @@@<1> use rsync, remote or local synchron target file. case1 @@@ Case1: source and target have the same filename, but content are differents. Then you run the rsync, What is the result? [root@station78 ~]# ls -R source_file/ target_file/ source_file/: file1 file2 target_file/: file1 file2 @@@source dir: [root@station78 ~]# cd source_file/ [root@station78 source_file]# cat file1 111 222 333 [root@station78 source_file]# cat file2 111 222 333 @@@target dir: [root@station78 ~]# cd target_file/ [root@station78 target_file]# cat file1 111 222 [root@station78 target_file]# cat file2 111111111111111111111111111111111 @@@ @@@Testing contents [root@station78 ~]# rsync -avz source_file/ target_file/ sending incremental file list ./ file1 file2 sent 162 bytes received 53 bytes 430.00 bytes/sec total size is 24 speedup is 0.11 [root@station78 ~]# cd target_file/ [root@station78 target_file]# cat file1 111 222 333 [root@station78 target_file]# cat file2 111 222 333 @@@ @@@<2> local case2 @@@ Case2: source and target have different filename, then What's the result? @@@source dir: [root@station78 ~]# cd source_file/ [root@station78 source_file]# cat file1 111 222 333 [root@station78 source_file]# cat file2 111 222 333 @@@target dir: [root@station78 target_file]# pwd /root/target_file [root@station78 target_file]# ls file3 [root@station78 target_file]# cat file3 xxxx @@@Testing [root@station78 ~]# rsync -avz source_file/ target_file/ sending incremental file list ./ file1 file2 sent 162 bytes received 53 bytes 430.00 bytes/sec total size is 24 speedup is 0.11 @@@ @@@Result: file3 do not be removed, and add file1 and file2. [root@station78 ~]# cd target_file/ [root@station78 target_file]# ls file1 file2 file3 [root@station78 target_file]# cat file1 111 222 333 [root@station78 target_file]# cat file2 111 222 333 [root@station78 target_file]# cat file3 xxxx 2@@@@ remote the same, just add user@[hostname|ip]:dir like rsync -avz root@station15:/root/sourcedir /root/targetdir rsync -avz /root/sourcedir root@station78:/root/targetdir Bear in mind: It is the files in source directory were copy to the target directory, if there are the same filename in target dir, then cover it by the file in source directory, if there are not the same filename in target dir, then do nothing. 3@@@@ When we need this tool? You backup something big. such as When I backup my Documents to my moving disk, It is very convenient and speed. You could use this in your shell script, then the shell script could be run in crontab for daily backup something. It is magic.