Basic Linux knowledge

Tips for Linux: press the tab key when you enter the su password. When you change the su password to the root user, the system will prompt you to enter the password, if the password is forgotten, you can use $: sudo passwd to set the password. 2. The file directory in llinux "/": root: stores the relevant files of the root user. home: bin: directory for storing Common commands sbin: permission-based command mnt: default directory for mounting optical drives and software drives boot: directory for storing boot-related files etc: configuration-related files (configuration in various environments) var: store frequently-changing data usr: the default folder for installing software (similar to program under win) dev: interface device file directory, for example, had indicates hard disk proc: Current System Core and program execution Information 3. linux running level 0: Shutdown (if set to this, the system cannot be entered) 1: single user 2: multi-user status without network service 3: multi-user status with network service (usually set to this) 4: The system uses 5: graphic interface reserved for the user (the graphic interface is displayed when the machine is started) 6. The common levels for system restart are 3 and 5. to modify the default running level, you can change the id of the file/etc/inittab to 5: initdefault: Data in this line. 4, common command -- help can view related operation man command can view the relevant documentation pwd: display the current directory cd: Switch directory ls: list Files And Directories (the following are the parameters used for this command) (for more information, see ls -- help) ls-a show hidden file ls-l show long list file (you can see the size and date) dir: it is also a list file (but the font has no color) mkdir: create directory rmdir: delete the empty directory touch: Create an empty file cp: Copy command (for example, cp hello hello2 is to copy the file hello to the folder hello2) cp-r dir1 dir2mv: move the file and change the file name (mv hello hello2 moves the hello file to the hello2 directory) rm: delete the file box directory rm-rf delete all content more: show the file content, with paging less: show the file content grep: query the content in the text (grep "find_name" wenjian) (grep "find_name" wenjian> the data retrieved by test is written to the file "test, here> overwrite> append write) l: Pipeline command (submit the result of the previous command to the command after pipeline l for processing) find search file and directory (find hello file) find/-name hello (meaning search for a hello file under the same directory) User Management (must switch to root) add User useradd name set password passwd name