Uid-related content of linux Users

The uid-related content of linux users is in linux. Users have user names and uid. Uid is a number used to uniquely identify a user. In linux, the File Permission is actually bound to the uid, rather than the seemingly user name. Specify the uid method when creating a user:
Shell code useradd [usernamen]-u [uid] www.2cto.com uid must be a number, must not be occupied, must be greater than or equal to 500, (uid less than 500 is managed by the System) modify the uid of a user:
Shell code usermod-u [username] [uid] Replace the File Permission uid in the file system;
Shell code find/path/xxx/-user [uid_1]-exec chown [uid_1] {}\;: recursively traverse the files in the/path/xxx/path, uid is the owner information of the uid_1 file, which is changed to uid_2;