ln软硬连接使用说明

[root@localhost /]# ln --help
Usage: ln [OPTION]... [-T] TARGET LINK_NAME   (1st form)
  or:  ln [OPTION]... TARGET                  (2nd form)
  or:  ln [OPTION]... TARGET... DIRECTORY     (3rd form)
  or:  ln [OPTION]... -t DIRECTORY TARGET...  (4th form)
In the 1st form, create a link to TARGET with the name LINK_NAME.
In the 2nd form, create a link to TARGET in the current directory.
In the 3rd and 4th forms, create links to each TARGET in DIRECTORY.
Create hard links by default, symbolic links with --symbolic.
When creating hard links, each TARGET must exist.  Symbolic links
can hold arbitrary text; if later resolved, a relative link is
interpreted in relation to its parent directory.

Mandatory arguments to long options are mandatory for short options too.
      --backup[=CONTROL]      make a backup of each existing destination file
  -b                          like --backup but does not accept an argument
  -d, -F, --directory         allow the superuser to attempt to hard link
                                directories (note: will probably fail due to
                                system restrictions, even for the superuser)
  -f, --force                 remove existing destination files
  -i, --interactive           prompt whether to remove destinations
  -L, --logical               make hard links to symbolic link references
  -n, --no-dereference        treat destination that is a symlink to a
                                directory as if it were a normal file
  -P, --physical              make hard links directly to symbolic links
  -s, --symbolic              make symbolic links instead of hard links
  -S, --suffix=SUFFIX         override the usual backup suffix
  -t, --target-directory=DIRECTORY  specify the DIRECTORY in which to create
                                the links
  -T, --no-target-directory   treat LINK_NAME as a normal file
  -v, --verbose               print name of each linked file
      --help     display this help and exit
      --version  output version information and exit

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:

Using -s ignores -L and -P.  Otherwise, the last option specified controls
behavior when the source is a symbolic link, defaulting to -P.

  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

Report ln bugs to
GNU coreutils home page: <>
General help using GNU software: <>
For complete documentation, run: info coreutils 'ln invocation'

1，创建软连接
ln -s 源文件 软连接文件
示例：
[root@localhost test]# ln -s srcfile softlink
[root@localhost test]# ll
total 0
lrwxrwxrwx. 1 root root 7 Feb  1 03:53 softlink -> srcfile
-rw-r--r--. 1 root root 0 Feb  1 03:47 srcfile
2，修改软连接
ln -s 软连接名 新源文件
示例：
[root@localhost test]# touch srcfile2
[root@localhost test]# ln -sf srcfile2 softlink
[root@localhost test]# ll
total 0
lrwxrwxrwx. 1 root root 8 Feb  1 04:03 softlink -> srcfile2
-rw-r--r--. 1 root root 0 Feb  1 04:01 srcfile
-rw-r--r--. 1 root root 0 Feb  1 04:03 srcfile2
3，修改软连接
示例：
[root@localhost test]# rm softlink
rm: remove symbolic link `softlink'? y
[root@localhost test]# ll
total 0
-rw-r--r--. 1 root root 0 Feb  1 04:01 srcfile
-rw-r--r--. 1 root root 0 Feb  1 04:03 srcfile2

4，硬链接不加参数-s就可以了
[root@localhost test]# ll
total 0
-rw-r--r--. 1 root root 0 Feb  1 04:01 srcfile
[root@localhost test]# ln srcfile hardlink
[root@localhost test]# ll
total 0
-rw-r--r--. 2 root root 0 Feb  1 04:01 hardlink
-rw-r--r--. 2 root root 0 Feb  1 04:01 srcfile
[root@localhost test]# touch srcfile2
[root@localhost test]# ll
total 0
-rw-r--r--. 2 root root 0 Feb  1 04:01 hardlink
-rw-r--r--. 2 root root 0 Feb  1 04:01 srcfile
-rw-r--r--. 1 root root 0 Feb  1 04:08 srcfile2
[root@localhost test]# cat srcfile srcfile
[root@localhost test]# echo srcfile >srcfile
[root@localhost test]# echo srcfile2 >srcfile2
[root@localhost test]# cat srcfile
srcfile
[root@localhost test]# cat srcfile2
srcfile2
[root@localhost test]# cat hardlink
srcfile
[root@localhost test]# ln -f srcfile2 hardlink
[root@localhost test]# cat hardlink
srcfile2
[root@localhost test]# ll
total 12
-rw-r--r--. 2 root root 9 Feb  1 04:09 hardlink
-rw-r--r--. 1 root root 8 Feb  1 04:09 srcfile
-rw-r--r--. 2 root root 9 Feb  1 04:09 srcfile2
[root@localhost test]# rm hardlink
rm: remove regular file `hardlink'? y
[root@localhost test]# ll
total 8
-rw-r--r--. 1 root root 8 Feb  1 04:09 srcfile
-rw-r--r--. 1 root root 9 Feb  1 04:09 srcfile2
[root@localhost test]#


5，大家看看root前面那个数字是啥意思，剩下的参数不太常用，没有仔细分析了，大家有兴趣欢迎一起讨论！