python centos doraemon entry of the (a) CRUD command
# ### 2.3 shortcut Crtl + the I clear the screen, corresponding to Clear Ctrl + S lock screen Crtl + Q unlocking Ctrl + C termination command Ctrl + A to move corresponding to the first command line Home Ctrl + E to move to the end of the line, corresponds end Ctrl + XX between the command cursor and the cursor moves back and forth head Ctrl + K remove the cursor to the end character position Ctrl + U delete the cursor to the beginning character alt + r to delete the entire line to be noted, alt would conflict with other shortcuts # ### 2.4 help - internal command - help the command - man bash - external command - COMMAMD - Help - the Command - H - man quit the Command q - search xx.docs official document Baidu `` `Python Usage: DATE [OPTION] ... [ + the FORMAT] or : DATE [-u | --utc | - [. SS] Universal] [MMDDhhmm [[CC] YY]] [] represents optionally ... represents a list [ -u | --utc | - Universal] optionally one -lh representatives -l - H DATE 0 52,805,271,980 set time ntpdate time.windows.com automatic time synchronization with the time server `` ` man - the arrows to control the output - carriage return to output the next line - the space switch to a screen - section: 1User commands 2 system calls 3 Call c library 4 . Device special file or files 5 . Profile 6 game 7 Miscellaneous 8 . Management command . 9 . Linux kernel the API # ## 3. directory structure - a directory tree structure is an inverted - from directory " / " start - Catalog strictly distinguish between sensitive - hidden file begins. - Road King delimiter is / file naming convention - file name length is 255 characters - including the path including up to 4095 characters - in addition to / and unexpected NULL, the other characters are to take effect - names are case-sensitive color representation: - blue for directory - green indicates a file can be executed - red archive - blue-green link files - ordinary white documents - Gray Other files file system structure - / boot file boot storage system, the kernel files, boot loader on the directory - / bin All users can use Some basic commands - / command sbin administrators can use management command - / lib some of the basic library files (windows are .dll linux is .so) - / lib64 specifically for 64-bit operating system, some auxiliary libraries - / etc directory configuration file - / home / the Username ordinary user's home directory - / root super administrator's home directory - / Media portable mobile device mount point - / opt to install a third-party program - / allowed on the srv service system use of data - / tmp directory to store temporary files - / usr installation route - / var to store data changes frequently, such as log - / proc virtual file used to store the kernel and processes related - / dev used to store equipment - / mnt mount temporary files - / generated files after system start or run the service - / SYS is stored in the associated hardware device virtualization file program components: - binary - / bin - / sbin - / usr / bin - / usr / sbin - / usr / local / bin - / usr / local / sbin - libraries - / lib - / lib64 - / usr / lib - / usr / lin64 - / the User / local / lib - / usr / local / lib64 - profiles - /etc - / etc / Directory - / usr / local / etc - help files - / usr / report this content share / man - / usr / report this content share / DOC - / usr / local / report this content share / man - / usr / local / report this content share / DOC # # ## 3.1 relative and absolute paths absolute paths: `` `shell from the root path to complete ` `` relative path: `` `shell relative to a file or directory is not / start .. on behalf of parent directory . represents the current path `` ` CD ` `` the shell [the root @ localhost etc] # CD [the root @ localhost ~] # [the root @ localhost ~] #cd - can quickly return to the last directory / etc / sysconfig / Network- scripts [root @ localhost Network -scripts] # cd - / root `` ` pwd prints the current directory ` `` shell [root @ localhost etc] # pwd / etc [root @ localhost etc] # cd sysconfig / Network-scripts / [root @ localhost Network-scripts] # pwd / etc / sysconfig / Network- scripts `` ` LS listed pointed out that the file or directory folder syntax: iS [OPTION] ... [fILE] ... `` `shell LS - a tired all the files (including hidden files) LS the -l = LL Changge use to display the files associated information LS -R (recursive) ls - D show the directory itself ls -1 (number 1) vertically display the file ls - S ordered according to the size of the file ls - LSR ascending order ls -d * / display list in the current directory, the directory can not be specified ls - H is displayed in a human readable way `` ` # ### 3.2 Touch to create an empty file modification files and more time stamp ` `` shell Touch is used to create the file modification time, and if the file exists, then the repair time to buy if you do not exist, create a file ` expanded command: ` `` the shell a { 1..10 } command to expand a { 1..10..2 } specified step length SEQ . 1 10 SEQ . 1 2 10 2 is the step size ' `` command quote: `` `shell date` ` $ (DATE) `` ` file wildcard - * represent zero or more characters characters - ? Represent any one character - ~ representative-directory - [0-9 ] represents a number - [az] letter, and comprises from az A- the Y - [AZ] letter, and comprises from AZ B- Z - [abcdef] represents wherein any of a - `a [^ abcdef]` inversion - [: Lower:] lowercase characters - [: Upper:] uppercase character - [; digit for:] digital - a-ZA- the Z all letters - [: Alpha:] any character or numeric - [: alnum:] represent all the letters and numbers statc viewing file status: `` `shell file: 'AA' Size: 0 Blocks: 0 Block IO: 4096 Regular empty file Device: fd00h / 64768d Inode: 19,864,315 Links:. 1 Access: ( 0644 / R & lt -rw-- r--) Uid: (0 / the root) Gid: (0 / the root) the Context: unconfined_u: object_r: admin_home_t: S0 Access : 2019-07-30 11: 57: 02.279384871 +0800 the Modify: 2019-07-30 11: 57: 02.279384871 +0800 Change: 2019-07-30 11: 57: 02.279384871 +0800 Birth: - access time: access to read atime file contents modified: modify to change the contents of the file mtime change time: change the file's contents ctime change `` ` # ### 3.3 copy files and folders ` `` shell Usage: cp [OPTION] ... [ - T ] sOURCE (source files) DEST (destination file) or: Cp [OPTION] ... the SOURCE ... DIRECTORY or : cp [OPTION] ... - t DIRECTORY the SOURCE ... `` ` - If the source is a file, then - if the target does not exist, create a new target, and the data is written to the target file inside - if the target file exists - if the target file is a directory, create a file with the same name as the source files directly below the target, the target file and writes data to a file - a file if the destination file directly on the cover, for safety reasons, we recommend cp with the - i use - if the source file is a multiple files - the target file if a file, then direct error - if the target file is a directory, then copied directly into the directory - If the source file is a directory, then - if the target does not exist, the specified directory is created, must - r option - if the directory exists - if the directory is a file, then direct error - if the target is a directory, then the directory create a new directory of the same name, and copy the files in the past commonly used parameters: the shell `` ` - prompt before i cover - not cover the tips before the n - R & lt recursive cover, copy all files in the directory and directory - F force - replication v show CP --backup = 2 Numbered 1.cfg .cfg file cover backup files to add digital - the p-retain the original properties, such as permissions `` ` # ### 3.4 move or rename ` `` shell Usage: mv [OPTION] ... [ - T] the SOURCE DEST or : mv [ the OPTION] ... ... the SOURCE DIRECTORY or : Music Videos [the OPTION] ... - T DIRECTORY the SOURCE ... - I interactive - F force - for backup before the cover b - V displays the progress ` # ### 3.5 delete `` shell ` RM [OPTION] ... FILE ... - i Interactive is a reminder before delete - f force delete - r recursive delete RM -rf / * caution RM -rf / * caution RM -rf / * caution cd / RM -rf * Be careful `` `