chmod sticky bit

 Let me explain how to work chmod +t. 

You know about permissions a lot of! Chmod 777 and you cannot delete files in directory? Why? Please check for output ls -l? Do you see -t permission? 

t permission is sticky bit. When we set sticky bit, only owner has use permission write on file. Noboady can write files in this dicectory only owner. 

write  to file = vi (edit), touch, rm, rm -rf 

write to file (with sticky bit) = vi (edit), touch, rm, rm -rf only owner even though chmod 777 to directory

1) How to check? (you see t)

[root@station ~]# ll /mnt/

total 0

drwxr-xr-t 2 root root  6 Feb  5 11:29 test

2) How to set? 

[root@station ~]# chmod +t /mnt/test/

[root@station ~]# chmod 1777 /mnt/test/

3) How to works? 

a) audrey create file

[audrey@kosice ~]$ touch /mnt/test/1.txt

[audrey@kosice ~]$ ll /mnt/test/1.txt

-rw-rw-r-- 1 audrey audrey 0 Feb  5 11:31 /mnt/test/1.txt

b) michael create file

[michael@kosice ~]$ touch /mnt/test/2.txt

[michael@kosice ~]$ ll /mnt/test/

total 0

-rw-rw-r-- 1 audrey  audrey  0 Feb  5 11:31 1.txt

-rw-rw-r-- 1 michael michael 0 Feb  5 11:31 2.txt

c) michael wanted remove the file

[michael@kosice ~]$ rm -rf /mnt/test/1.txt

rm: cannot remove '/mnt/test/1.txt': Operation not permitted

d) michael wanted to edit the file

[michael@kosice ~]$ echo I am hacker >>  /mnt/test/1.txt

-bash: /mnt/test/1.txt: Permission denied

e) michael creted new file

[michael@kosice ~]$ echo I am very bad hacker! God Dammit > /mnt/test/3.txt

[michael@kosice ~]$ cat /mnt/test/3.txt

I am very bad hacker! God Dammit

[michael@kosice ~]$