File Permissions
Linux permissions: SUID, SGID, and sticky bit | Enable Sysadmin
When an file is created there is an default permission that is applied to them. This default permission can be viewed and changed using the umask command
chmod ug+rw <filename> # Add permissions
chmod ug=rw <filename> # Set Exact
chmod 764 <filename>Flags
4: Read, 2: Write, 1: Execute
u: User, g: Group, o: Others, a: All
-R: Recursively change permissions
Permissions for Directory
r: List Directory contents
w: Rename, Create or Remove files
x: Search (Enter the Directory)
Special Permissions
Special Bits
Set UID/GID Bit (Run file as owner with owner permissions)
In Permissions represented by 4000 (SUID), 2000 (SGID) & 6000 (Both)
The “x” bit is replaced with “s” if this is set
SUID : Run file with permissions of file owner
SGID : Run file with permissions of the group owner
Sticky Bit
Sticky Bit (Only file owner can rename and delete file in the folder)
This permission works at the directory level
It is represented by “t” in place of the execute “x” bit in others section (rw-rw-rwt)
In permission represented by 1000
Identifying File types in Linux - Linux Tutorials - Learn Linux Configuration
Ownership Commands
# Change Owner
chown <username> <filename>
chown <username>:<group-name> <filename>
# Change Group
chgrp <group-name> <filename>
groups <username> # Returns groups that contain the user