Text | Binary | Directory | |
Read | cat <file> | cp /bin/ls | ls |
Write | cat > <file> | cc a.c | rm <directory> |
eXecute | ./<file> | ls | cd <directory> |
Only 2 users can change the permissions of a file
- the Owner
- super user or root
ls -l
Owner-Group-Others HardLinks username groupName bytes date filename
drwxrwxr-x 2 trainee trainee 4096 Jun 14 15:03 as
-rw-rw-r-- 1 trainee trainee 0 Jun 14 14:27 f2
-rw-rw-r-- 1 trainee trainee 148 Jun 14 14:28 f3
-rw-rw-r-- 1 trainee trainee 148 Jun 14 14:28 f4
-rw-rw-r-- 1 trainee trainee 888 Jun 14 14:29 f5
-rw-rw-r-- 1 trainee trainee 0 Jun 14 15:10 fruits
-rw-rw-r-- 1 trainee trainee 0 Jun 14 15:10 g1
-rw-rw-r-- 1 trainee trainee 0 Jun 14 15:10 g2
Change permissions on a file
- Numerical: use chmod 777 filename all permissions to a file.
- Symbolic: use chmod a+x,g-w <filename> [User Group] [+/-] [r/w/x]
UMASK:
- specifies what has to be denied
- its only for newly created files
you can find out umask by typing umask
[trainee@localhost purna]$ umask
0002 the last three specify what permission to deny to the owner group and others
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