最後更新: 2021-02-19

目錄

readlink

Print resolved symbolic links(找出指向的 file) or canonical file names

i.e.

ln -s test.txt link.txt

readlink link.txt

test.txt

Hard Link

Work with hardlink

mkdir tmp; cd tmp

echo test > a.txt

ln a.txt b.txt                # b.txt --hard link--> a.txt

ls -i1                           # -i --inode, hard link file 係有相同 inode

712963 a.txt
712963 b.txt

亦可以用 stat

stat a.txt

  File: a.txt
  Size: 5               Blocks: 8          IO Block: 4096   regular file
Device: fd00h/64768d    Inode: 712963      Links: 2
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2022-01-03 13:20:38.053478553 +0800
Modify: 2022-01-03 13:20:38.053478553 +0800
Change: 2022-01-03 13:20:41.541419430 +0800
 Birth: -

find . -inum              # 找出 hardlink 出什麼 file

./a.txt
./b.txt

# -xdev   #       limit to one filesystem

# ! -type d        reject directories. the . and .. entries mean they're always linked.

find tmp/ -xdev \! -type d -links +1  # 找出有 hardlink 的 file

Hard link with rsync

# 沒有 Hard Link 時

rsync -a tmp 192.168.88.31:/root

# On Host 192.168.88.31

ls -i1 tmp/

17537802 a.txt
17537805 b.txt

# Hard Link 時

rsync -aH tmp 192.168.88.31:/root

ls -i1 tmp/

17537802 a.txt
17537802 b.txt

no-dereference

# treat LINK_NAME as a normal file if it is a symbolic link to a directory

-n, --no-dereference

應用

ln -sfn /usr/local/bin/python3.7 /usr/bin/python3.7