cp拷贝
1 cp 拷贝、复制
NAME
cp - copy files and directories
SYNOPSIS
cp [OPTION]... [-T] SOURCE DEST -- cp 源位置 目标位置
cp [OPTION]... SOURCE... DIRECTORY
cp [OPTION]... -t DIRECTORY SOURCE...
DESCRIPTION
Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY. 拷贝一个文件（或多个文件）到目标目录
Mandatory arguments to long options are mandatory for short options too.
-a, --archive
same as -dR --preserve=all
--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 强制复制
if an existing destination file cannot be opened, remove it and try again (redundant if the -n option is used)
如果如已有的目标文件不能打开，删之，在尝试一次拷贝
-i, --interactive 交互式拷贝
prompt before overwrite (overrides a previous -n option) 如果目标文件已经存在，在覆盖时或询问是否覆盖
-H follow command-line symbolic links in SOURCE
-n, --no-clobber
do not overwrite an existing file (overrides a previous -i option)
-P, --no-dereference 非解除参考（如果源是一个软链接文件，则只拷贝该连接，不拷贝文件本身）
never follow symbolic links in SOURCE
测试：
|
[hadoop3@hadoop3 ~]$ ln -s file01.dat file01-slink.dat ##创建软连接文件file01-slink.dat [hadoop3@hadoop3 ~]$ ll total 4 -rw-rw-r--. 1 hadoop3 hadoop3 171 Jul 12 10:51 file01.dat lrwxrwxrwx. 1 hadoop3 hadoop3 10 Jul 12 10:53 file01-slink.dat -> file01.dat
[hadoop3@hadoop3 ~]$ ln file01.dat file01-hlink.dat ##创建硬连接文件file01-hlink.dat [hadoop3@hadoop3 ~]$ ll total 8 -rw-rw-r--. 2 hadoop3 hadoop3 171 Jul 12 10:51 file01.dat -rw-rw-r--. 2 hadoop3 hadoop3 171 Jul 12 10:51 file01-hlink.dat lrwxrwxrwx. 1 hadoop3 hadoop3 10 Jul 12 10:53 file01-slink.dat -> file01.dat
[hadoop3@hadoop3 ~]$ cp -P file01-slink.dat backup/ ##非解除参考拷贝 [hadoop3@hadoop3 ~]$ ls -al backup/ total 8 drwxrwxr-x. 2 hadoop3 hadoop3 4096 Jul 12 10:56 . drwx------. 3 hadoop3 hadoop3 4096 Jul 12 10:55 .. lrwxrwxrwx. 1 hadoop3 hadoop3 10 Jul 12 10:56 file01-slink.dat -> file01.dat ##因为backup目录中没有file01.dat文件，所以下面的cat报错
[hadoop3@hadoop3 backup]$ cat file01-slink.dat cat: file01-slink.dat: No such file or directory
[hadoop3@hadoop3 ~]$ cp file01.dat backup/ ##手动把符号链接引用的源文件拷贝到backup目录，cat就可以查看符号连接文件的内容了 [hadoop3@hadoop3 ~]$ cd backup/ [hadoop3@hadoop3 backup]$ ls -ln total 4 -rw-rw-r--. 1 500 500 171 Jul 12 11:05 file01.dat lrwxrwxrwx. 1 500 500 10 Jul 12 10:56 file01-slink.dat -> file01.dat [hadoop3@hadoop3 backup]$ cat file01.dat file01 -l, --link link files instead of copying
sdfdsf
dgddsgd gdfgdfhhgfhhfghfghfgjfjhgjhg 1111111111111111111111111111111111111111111111111 |
-L, --dereference
always follow symbolic links in SOURCE
|
[hadoop3@hadoop3 ~]$ cp -L file01-slink.dat backup/ ##软连接文件file01-slink.dat拷贝到backup目录中，得到的目的文件的大小为171个字节 [hadoop3@hadoop3 ~]$ ls -ln backup/ ##cp -L 拷贝软连接时，会把连接引用的源文件的内容一起拷贝过来，得到的是一个普通的文件 -- 即解引用 total 4 -rw-rw-r--. 1 500 500 171 Jul 12 11:08 file01-slink.dat
[hadoop3@hadoop3 ~]$ cat backup/file01-slink.dat file01 -l, --link link files instead of copying
sdfdsf
dgddsgd gdfgdfhhgfhhfghfghfgjfjhgjhg 1111111111111111111111111111111111111111111111111 |
-p same as --preserve=mode,ownership,timestamps
--preserve[=ATTR_LIST] 连同文件的属性一起复制过去（而不是使用默认的属性 --- 备份常用）
preserve the specified attributes (default: mode,ownership,timestamps), if possible additional attributes: context, links, xattr, all
保存特定的属性（如，文件的模式、所有者、时间戳） 如果可能附加的属性也会保留
-c 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 递归地拷贝目录
--reflink[=WHEN]
control clone/CoW copies. See below.
--remove-destination
remove each existing destination file before attempting to open it (contrast with --force) 移除每个现存的目标文件（在试图打开之前）
--sparse=WHEN
control creation of sparse files. See below. 控制稀疏文件的创建
--strip-trailing-slashes
remove any trailing slashes from each SOURCE argument 移除每个源参数中的末尾斜杠
-l, --link 硬连接
link files instead of copying
-s, --symbolic-link 软连接
make symbolic links instead of copying 做符号连接（当然是软连接）而不是拷贝
-S, --suffix=SUFFIX
override the usual backup suffix 指定通用的备份前缀
-t, --target-directory=DIRECTORY 目标dest是一个目录
copy all SOURCE arguments into DIRECTORY 拷贝所有源参到目录
-T, --no-target-directory 目标dest是一个文件
treat DEST as a normal file 把DEST参数看作为一个普通的文件
-u, --update
copy only when the SOURCE file is newer than the destination file or when the destination file is missing
更新式拷贝 --- 仅当源文件比目标文件新或目标文件丢失时，才进行拷贝
-v, --verbose
explain what is being done
-x, --one-file-system
stay on this file system
-Z, --context=CONTEXT
set security context of copy to CONTEXT
--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.
默认，执行的是一个轻量的拷贝，仅拷贝哪些修改了的数据块
If this is not possible the copy fails, or if --reflink=auto is specified, fall back to a standard copy. 指定--reflink=auto回到标准拷贝模式
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) 如果version_control环境变量值为none，则拷贝时不做备份（即使指定了--backup选项）
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.
cp使用：
1 同时拷贝多个文件
格式： cp 文件1 文件2 目的目录
|
[hadoop3@hadoop3 ~]$ ls -ln total 16 -rw-rw-r--. 1 500 500 176 Jul 12 11:15 a_1.txt -rw-rw-r--. 1 500 500 137 Jul 12 11:16 a_2.txt -rw-rw-r--. 1 500 500 106 Jul 12 11:16 a_3.txt drwxrwxr-x. 2 500 500 4096 Jul 12 11:16 files [hadoop3@hadoop3 ~]$ cp a_1.txt a_2.txt files/ [hadoop3@hadoop3 ~]$ ls -ln files/ total 8 -rw-rw-r--. 1 500 500 176 Jul 12 11:17 a_1.txt -rw-rw-r--. 1 500 500 137 Jul 12 11:17 a_2.txt |
2 拷贝一个目录
|
[hadoop3@hadoop3 ~]$ cp -r files files_backup [hadoop3@hadoop3 ~]$ tree . ├── a_1.txt ├── a_2.txt ├── a_3.txt ├── files │ ├── a_1.txt │ └── a_2.txt └── files_backup ├── a_1.txt └── a_2.txt |
3硬连接拷贝，而不仅仅是拷贝一个文件（拷贝出来的文件与源文件会同步更新的）
|
[hadoop3@hadoop3 ~]$ mkdir links [hadoop3@hadoop3 ~]$ cp -l a_2.txt links [hadoop3@hadoop3 ~]$ ls -ln links total 4 -rw-rw-r--. 2 500 500 137 Jul 12 11:16 a_2.txt
[hadoop3@hadoop3 ~]$ echo ' adddd' >> a_2.txt ##向源文件追加字符 [hadoop3@hadoop3 ~]$ cat a_2.txt 22222222222222222222222 2222222222222222222222222222222 222222222222222222222222222222222222 2222222222222222222222222222222222222222222 adddd [hadoop3@hadoop3 ~]$ cat links/a_2.txt ##硬连接文件的内容同步更新了 22222222222222222222222 2222222222222222222222222222222 222222222222222222222222222222222222 2222222222222222222222222222222222222222222 adddd |
4 软连接拷贝 -- 符号链接
|
[hadoop3@hadoop3 ~]$ cp -s a_3.txt links/ cp: `links/a_3.txt': can make relative symbolic links only in current directory ##跨目录不能创建相对符号连接
[hadoop3@hadoop3 ~]$ cp -s /home/hadoop3/a_3.txt links [hadoop3@hadoop3 ~]$ ls -ln links total 4 -rw-rw-r--. 2 500 500 145 Jul 12 11:28 a_2.txt lrwxrwxrwx. 1 500 500 21 Jul 12 11:34 a_3.txt -> /home/hadoop3/a_3.txt |
