Basic use of cp command in Linux system

1. Check the local system version

[root@node ~]# cat /etc/os-release 
NAME="CentOS Linux"
VERSION="7 (Core)"
ID_LIKE="rhel fedora"
PRETTY_NAME="CentOS Linux 7 (Core)"


2. cp command help

[root@node ~]# cp --help
Usage: cp [OPTION]... [-T] SOURCE DEST
  or:  cp [OPTION]... -t DIRECTORY SOURCE...
Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY.

Mandatory arguments to long options are mandatory for short options too.
  -a, --archive                same as -dR --preserve=all
      --attributes-only        don't copy the file data, just the attributes
      --backup[=CONTROL]       make a backup of each existing destination file
  -b                           like --backup but does not accept an argument
      --copy-contents          copy contents of special files when recursive
  -d                           same as --no-dereference --preserve=links
  -f, --force                  if an existing destination file cannot be
                                 opened, remove it and try again (this option
                                 is ignored when the -n option is also used)
  -i, --interactive            prompt before overwrite (overrides a previous -n
  -H                           follow command-line symbolic links in SOURCE
  -l, --link                   hard link files instead of copying
  -L, --dereference            always follow symbolic links in SOURCE
  -n, --no-clobber             do not overwrite an existing file (overrides
                                 a previous -i option)
  -P, --no-dereference         never follow symbolic links in SOURCE
  -p                           same as --preserve=mode,ownership,timestamps
      --preserve[=ATTR_LIST]   preserve the specified attributes (default:
                                 mode,ownership,timestamps), if possible
                                 additional attributes: context, links, xattr,
  -c                           deprecated, same as --preserve=context
      --no-preserve=ATTR_LIST  don't preserve the specified attributes
      --parents                use full source file name under DIRECTORY
  -R, -r, --recursive          copy directories recursively
      --reflink[=WHEN]         control clone/CoW copies. See below
      --remove-destination     remove each existing destination file before
                                 attempting to open it (contrast with --force)
      --sparse=WHEN            control creation of sparse files. See below
      --strip-trailing-slashes  remove any trailing slashes from each SOURCE
  -s, --symbolic-link          make symbolic links instead of copying
  -S, --suffix=SUFFIX          override the usual backup suffix
  -t, --target-directory=DIRECTORY  copy all SOURCE arguments into DIRECTORY
  -T, --no-target-directory    treat DEST as a normal file
  -u, --update                 copy only when the SOURCE file is newer
                                 than the destination file or when the
                                 destination file is missing
  -v, --verbose                explain what is being done
  -x, --one-file-system        stay on this file system
  -Z                           set SELinux security context of destination
                                 file to default type
      --context[=CTX]          like -Z, or if CTX is specified then set the
                                 SELinux or SMACK security context to CTX
      --help     display this help and exit
      --version  output version information and exit

By default, sparse SOURCE files are detected by a crude heuristic and the
corresponding DEST file is made sparse as well.  That is the behavior
selected by --sparse=auto.  Specify --sparse=always to create a sparse DEST
file whenever the SOURCE file contains a long enough sequence of zero bytes.
Use --sparse=never to inhibit creation of sparse files.

When --reflink[=always] is specified, perform a lightweight copy, where the
data blocks are copied only when modified.  If this is not possible the copy
fails, or if --reflink=auto is specified, fall back to a standard copy.

The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX.
The version control method may be selected via the --backup option or through
the VERSION_CONTROL environment variable.  Here are the values:

  none, off       never make backups (even if --backup is given)
  numbered, t     make numbered backups
  existing, nil   numbered if numbered backups exist, simple otherwise
  simple, never   always make simple backups

As a special case, cp makes a backup of SOURCE when the force and backup
options are given and SOURCE and DEST are the same name for an existing,
regular file.

GNU coreutils online help: <>
For complete documentation, run: info coreutils 'cp invocation'

3. the basic parameters of the cp command

Parameter description.

-a: This option is usually used when copying directories; it preserves links, file attributes, and copies everything in the directory. Its effect is equal to the dpR parameter combination.
-d: Keeps the link when copying. The link described here is equivalent to a shortcut in Windows.
-f: Overwrites an already existing target file without prompting.
-i: In contrast to the -f option, the user is prompted to confirm whether to overwrite the target file before it is overwritten, and the target file is overwritten when y is answered.
-p: In addition to copying the contents of the file, the modification time and access rights are also copied to the new file.
-r: If the given source file is a directory file, all subdirectories and files under that directory will be copied.
-l: Does not copy the file, just generates the link file.

4.the daily use of the cp command

1. Copy a folder to another folder

[root@node ~]# cp -r /etc/ /test/
[root@node ~]# ll /test/
total 12
drwxrwxrwx.   2 root root    6 Oct 27 13:10 dir01
drwxrwx---.   2 root root    6 Oct 27 13:10 dir02
d------rwx.   2 root root    6 Oct 27 13:10 dir03
drwxr-xr-x  146 root root 8192 Nov 12 22:56 etc

2. Copy the contents of one folder to another folder

[root@node ~]# mkdir /home/{test01,test02}
[root@node ~]# touch /home/test01/file1
[root@node ~]# cp -r /home/test01/* /home/test02/
[root@node ~]# ll /home/test02/
total 0
-rw-r--r-- 1 root root 0 Nov 12 23:02 file1
[root@node ~]#

5. Precautions for the cp command

1. Copy a folder to another folder

The following 4 methods are to transfer the test01/ directory and its recursive subdirectories and files to another folder

cp -r /home/test01 /home/test02
cp -r /home/test01  /home/test02/
cp -r /home/test01/ /home/test02
cp -r /hometest01/ /home/test02/

2. Copy the contents of one folder to another folder

The following two methods are all about copying the contents of one folder to another folder

cp -r /hometest01/* /home/test02/
cp -r /hometest01/* /home/test02

6. Common operations when backing up files

Recursive copying, the copied data will retain the time stamp and other information of the original data (specifically: time stamp + ownership + copy link file attributes instead of the file itself)

[root@node ~]# cp -a /etc/ /backup/
[root@node ~]# ll /backup/
total 12
drwxr-xr-x. 146 root root 8192 Nov 12 14:03 etc
[root@node ~]# ls /backup/etc/
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