Linux permissions are most important task when it comes to application installation and security hardening of your Linux servers.
Linux permissions are – READ [4], WRITE [2], EXECUTE [1]
These permissions are presented with numbers as 4, 2, 1.
Any File or Directory has a OWNER, GROUP AND OTHERS
OWNER – Owner is the one who created the file or DIR or has the ownership to the file/directory
GROUP – Group is referred to more then one user to have access to the files or directories.
OTHERs – any user who is not a part of owner or group is termed as others.
Below snip showing different set of permissions –
1. Owner has READ ONLY access and group and others have no permissions i.e 400
2. Owner has READ, WRITE ONLY access and group and others have no permissions i.e 600
3. Owner has READ, WRITE and EXECUTE access and group and others have no permissions i.e. 700
4. Owner has all permissions and Group has READ ONLY access and others have no permissions i.e 0740
5. Owner has all permissions and Group has READ and WRITE ONLY access and others have no permissions i.e 0760
6. Owner has all permissions and Group has All permissions i.e. READ, WRITE and EXECUTE access and others have NO permissions i.e 0770
7. Owner, GROUP has all permissions and Others have only READ access i.e 0774
8. Owner, GROUP has all permissions and Others have only READ and WRITE access i.e 0776
9. Owner, GROUP has all permissions and Others Also have all access that is READ, WRITE and EXECUTE privilleges i.e 0777 [777 is Not Recommended on any of servers as it is open to world privilleges and very insecure, do not use it, not even on your non-prod servers]
