File operation command

One 、 File operations

1. View the current working directory

Every shell And system processes have a current working directory CWD：current work directory

Show the current shell CWD The absolute path of

pwd command : printing working directory

•   -P Show real physical path
•   -L Show link path （ Default ）

2. Absolute and relative paths

• Absolute path                

         With a forward slash / The root directory starts

         Full file location path

         Can be used whenever you want to specify a filename

• Relative paths

         Don't start with a slash

         In general , The path relative to the current working directory , In a special situation , It's a location relative to a directory

         You can specify a filename as a short form

Base name ：basename, Just take the file name instead of the path

Directory name ：dirname, Path only , Don't use the file name

3. Change directory

command cd ： change directory Change the directory

Options ：-P Switch to physical path , Instead of the softlink Directory

You can use absolute or relative paths

• Switch to the parent directory ： cd ..
• Switch to the current user's home directory ： cd
• Switch to the previous working directory ： cd -

4. List the contents of the catalog

ls The command can list the contents of the current directory or specify a directory

usage ：

ls [options] [files_or_dirs]

Common options ：

• -a Contains hidden files
• -l Show additional information
• -R Directory recursion
• -ld Catalog and symlink information
• -1 The document line shows
• -S Sort from big to small
• -t Press mtime Sort
• -u coordination -t Options , Show and press atime Sort from new to old
• -U Display... In the order in which the contents are stored
• -X Sort by file suffix
• -F Attach different symbols when displaying different types of files ：*/=>@|
• -C Documents are long , Display files in multiple columns , The default is a column （ standard output ）

explain ：

        ls The color when viewing files with different suffixes is determined by /etc/DIR_COLORS and @LS_COLORS Variable definitions

        ls -l See the size of the file , It's not necessarily the size of the space actually occupied by the actual file

5. View file status stat

Document related information ：metadata, data

Each file has three timestamps ：

• access time Access time ,atime, Read file contents
• modify time Modification time ,mtime, Change file content （ data ）
• change time Change time ,ctime, Metadata changed

6. Determine the contents of the document

Files can contain multiple types of data , Use file Command to check the type of file , Then determine the appropriate open command or application to use

Format

file [options] <filename>...

Common options :

• -b When listing file identification results , Do not show file name
• -f filelist Lists the files filelist The file type of the file name in
• -F Replace the output file name with the specified separator ”:” Separator
• -L View the file type of the corresponding soft link
• --help Display command online help

7. File wildcard pattern wildcard pattern

File wildcards can be used to match multiple files that meet the criteria , It is convenient to manage files in batches

The wildcard has a specific symbol , Express a specific meaning , This special symbol is called yuan meta character

Common wildcards are as follows ：

*  Matches zero or more characters , But don't match  "."  Opening file , That is, hidden files 
?  Match any single character , A Chinese character is also a character 
~  Current user home directory 
~mage  user mage Home directory 
.  and  ~+  Current working directory 
~-    Previous working directory 
[0-9]  Match number range 
[a-z]  A letter 
[A-Z]  A letter 
[wang]  Match any character in the list 
[^wang]  Match all characters in the list except for 
[^a-z]  Match all characters in the list except for 

[:digit:]： Arbitrary number , amount to 0-9
[:lower:]： Any lowercase letter , Express  a-z
[:upper:]:  Any capital letter , Express  A-Z 
[:alpha:]:  Any upper and lower case letters 
[:alnum:]： Any number or letter 
[:blank:]： Horizontal white space characters 
[:space:]： Horizontal or vertical white space characters 
[:punct:]： Punctuation 
[:print:]： Printable characters 
[:cntrl:]： control （ unprintable ） character 
[:graph:]： Graphic characters 
[:xdigit:]： Hexadecimal characters 

8. Create empty files and refresh time

touch Command can be used to create an empty file or refresh the file time

Format ：

touch [OPTION]... FILE...

Option description ：

• -a Just change atime and ctime
• -m Just change mtime and ctime
• -t [[CC]YY]MMDDhhmm[.ss] Appoint atime and mtime The timestamp
• -c If the file doesn't exist , Do not create

9. Copy files and directories

utilize cp（copy） Commands can be used to copy files or directories

Format

cp [OPTION]... [-T] SOURCE DEST
cp [OPTION]... SOURCE... DIRECTORY
cp [OPTION]... -t DIRECTORY SOURCE...

Common options

• -i If the goal already exists , Prompt whether to cover before covering
• -n No coverage , Pay attention to the order of the two
• -r, -R Recursively copies directories and everything inside
• -a file , amount to -dR --preserv=all, Commonly used for backup functions
• -d --no-dereference --preserv=links Do not copy the original file , Copy only the link name
• --preserv[=ATTR_LIST]

                mode: jurisdiction

                ownership: Belong to the main genus group

                timestamp:

                links

                xattr

                context

                all

• -p equivalent --preserv=mode,ownership,timestamp
• -v --verbose
• -f --force
• -u --update Copy only files that the source updates or the destination does not exist
• -b Goals exist , Backup before overwriting , The default form is filename~ , Keep only the most recent backup

10. Move and rename files

        mv Commands can be used to move and rename files or directories

         Move data in the same partition , fast : There's no change in the location of the data

         Different partitions move data , It's relatively slow : The location of the data has changed

         Format ：

mv [OPTION]... [-T] SOURCE DEST
mv [OPTION]... SOURCE... DIRECTORY
mv [OPTION]... -t DIRECTORY SOURCE...

Common options ：

• -i Interactive
• -f mandatory
• -b Goals exist , Backup before overwriting

utilize rename You can batch modify the file name

Format ：

rename [options] <expression> <replacement> <file>...

11. Delete file

Use rm The command can delete files

Be careful ： This command is very dangerous , Careful use , It is recommended to use mv Instead of rm

Format ：

rm [OPTION]... FILE...

Common options ：

• -i Interactive
• -f Mandatory deletion
• -r recursive
• --no-preserve-root Delete /

rm Although the file was deleted , But deleted files can still be recovered , In scenarios with high security requirements , have access to shred Safely delete files

shred Format

shred [OPTION]... FILE...

Common options ：

• -z   Last overlay add 0, To hide the override operation
• -v Able to display operation progress
• -u Truncate and delete files after overwriting
• -n # Specify the number of times to overwrite the contents of the file （ The default value is 3 Time ）

Two 、 Directory operation

1. Show tree tree

Common options ：

• -d: Show only directories
• -L level： Specify the number of levels to display
• -P pattern: Only display specified by wild-card pattern Match the path to

2. Create directory mkdir

Common options ：

• -p: There is no error reporting , And can automatically create the required directories
• -v: Show details
• -m MODE: When creating a directory, you can directly specify permissions

3. Delete empty directory rmdir

Common options ：

• -p Recursively delete the parent empty directory
• -v Show details

Be careful ：rmdir Only empty directories can be deleted , If you want to delete a non empty directory , have access to rm -r command , Delete tree recursively