Make a little progress every day-linux-cp

Make a little progress every day-linux-cp
1 Introduction

The cp command is used to copy files or directories. It is one of the most common commands in Linux. In general, shell sets an alias. When copying a file under the command line, if the target file already exists, it will ask whether to overwrite the file, whether or not you use the-I parameter. However, if the cp is executed in a shell script, if the-I parameter is not displayed, the system does not ask whether to overwrite it.

 

[Root @ Nagios ~] # Alias

Alias cp = 'cp-I'

2. Command Format

Cp [Option]... [-T] source objective

Or: cp [Option]... source... directory

Or: cp [Option]...-t directory source...

Three Common Parameters

-A, -- archive equals to-dR -- preserve = all

-- Backup [= CONTROL creates a backup for each existing target file

-I, -- interactive overwrite the previous query (invalidate the previous-n option)

-L, -- link file without copying

-L, -- dereference always follows the Symbolic Link

-N, -- no-clobber do not overwrite existing files (invalidate the previous-I option)

-R,-r, -- recursive Recursively copies all contents in the directory and Its subdirectories.

 

Iv. Uncommon Parameters

-A, -- archive equals to-dR -- preserve = all

-- Backup [= CONTROL creates a backup for each existing target file

-B is similar to -- backup but does not accept parameters

-- Copy-contents: In recursive processing, copying special file content

-D equals -- no-dereference -- preserve = links

-F, -- force: if the target file cannot be opened, remove it and try again (when-n Option

This option does not need to be selected if it exists)

-I, -- interactive overwrite the previous query (invalidate the previous-n option)

-H follows the command line symbolic link in the source file

-L, -- link file without copying

-L, -- dereference always follows the Symbolic Link

-N, -- no-clobber do not overwrite existing files (invalidate the previous-I option)

-P, -- no-dereference does not follow the symbolic link in the source file

-P equals to -- preserve = mode, ownership, timestamp

-- Preserve [= the attribute list retains the specified attribute (default: mode, ownership, timestamp). If

Additional attributes may be maintained: environment, Link, xattr, etc.

-C sameas -- preserve = context

-- Sno-preserve = the attribute list does not retain the specified file attribute.

-- All directories in the source file path are created in the target directory before parents is copied.

-R,-r, -- recursive Recursively copies all contents in the directory and Its subdirectories.

-- Reflink [= WHEN] controls clone/CoW copies. See the following example.

-- Remove-destination delete an existing destination before trying to open the target file

File (relative to the -- force option)

-- Sparse = WHEN controls how to create sparse files

-- Strip-trailing-slashes Delete the slashes at the end of all source files/directories in the Parameter

-S, -- symbolic-link: Only Create symbolic Links without copying files

-S, -- suffix = suffix specifies the suffix of the backup file

-T, -- target-directory = directory: All the source files/Directories specified by Parameters

Copy to target directory

-T, -- no-target-directory treats the target directory as a common file

-U, -- update copy only whenthe SOURCE file is newer

Than thedestination file or when

Destination file is missing

-V, -- verbose explain what isbeing done

-X, -- one-file-system stay on thisfile system

-Z, -- context = CONTEXT set securitycontext of copy to CONTEXT

-- Help: displays the help information and exits.

-- Version: displays the version information and exits.

Example 5: copy a single file to the directory. The object does not exist.

[Bzfys @ Nagiost1] $ tree

.

── T2

── T3

│ ?? ── T2

── T4
[Bzfys @ Nagios t1] $ cp t4./t3/

[Bzfys @ Nagiost1] $ tree

.

── T2

── T3

│ ?? ── T2

│ ?? ── T4

── T4

5.1 copy a single file to the directory. The file target exists. Add-a and no-.

[Root @ Nagiost1] # ll

Total usage 8

Drwxrwxr-x 2 bzfys 4096 June 18 09:16 t2

Drwxrwxr-x 3 bzfys 4096 June 18 09:18 t3

-Rw-r -- 1 bzfys 0 June 18 09:17 t4

[Root @ Nagiost1] # cp t4 t3/

Cp: overwrite "t3/t4 "? Y

[Root @ Nagiost1] # ll t3/

Total usage 4

Drwxrwxr-x 2 bzfys 4096 June 18 09:16 t2

-Rw-r -- 1 bzfys 0 June 18 09:22 t4

[Root @ Nagiost1] # cp-p t4 t3/

Cp: overwrite "t3/t4 "? Y

[Root @ Nagiost1] # ll t3/

Total usage 4

Drwxrwxr-x 2 bzfys 4096 June 18 09:16 t2

-Rw-r -- 1 bzfys 0 June 18 09:17 t4

It is not hard to see that the attributes such as the file timestamp copied with the-p parameter will not change.

5.2 copy directory

[Root @ Nagiost1] # cp t3 t5

Cp: skipping the directory "t3"

[Root @ Nagiost1] # cp-a t3 t5

[Root @ Nagiost1] # tree

.

── T2

── T3

│ ?? ── T2

│ ?? ── T4

── T4

── T5

── T2

── T4

 

5 directories, 3 files

It can be seen that if you want to copy a directory, you need the-a or-r parameter (the-r parameter is demonstrated later)

5.3 copy one directory to another

[Root @ Nagiost1] # cp t3 t6/

Cp: skipped directory "t3

[Root @ Nagiost1] # cp-r t3 t6

[Root @ Nagiost1] # tree

.

── T2

── T3

│ ?? ── T2

│ ?? ── T4

── T4

── T5

│ ?? ── T2

│ ?? ── T4

── T6

── T3

── T2

── T4

 

8 directories, 4 files

[Root @ Nagiost1] # cp-r t3/t6/

Cp: does it cover "t6/t3/t4 "? Y

[Root @ Nagiost1] # tree

.

── T2

── T3

│ ?? ── T2

│ ?? ── T4

── T4

── T5

│ ?? ── T2

│ ?? ── T4

── T6

── T3

── T2

── T

We can see that the final result of the addition/unaddition is the same.