What is umask?#
The umask command sets the default permissions for newly created files and directories.
It acts as a “mask” that subtracts specified permissions from the maximum permissions, ensuring new files and directories are created with secure defaults.
It’s also a process-based tool, which sets the default permission as long as it’s running in the background.
Essential Commands#
| Commands | Description |
|---|
umask | Check the current umask value |
umask 022 | Set the new umask value |
umask u=rwx, g=rx, o=r | Sets permission using symbolic notation (equivalent to 022) |
Subcommands#
| Commands | Description |
|---|
umask -S | Print mask in symbolic form |
umask -p | Print mask as command for reuse |
| |
Example#
- Change
umask to 027 and create a new file:
iamyaash@pi5:~/umask $ umask
0022
iamyaash@pi5:~/umask $ touch testFile.txt
iamyaash@pi5:~/umask $ ll
total 0
-rw-r--r-- 1 iamyaash iamyaash 0 Jun 25 11:43 testFile.txt
iamyaash@pi5:~/umask $ umask 027 && umask
0027
iamyaash@pi5:~/umask $ touch testFile_027.txt
iamyaash@pi5:~/umask $ ll
total 0
-rw-r----- 1 iamyaash iamyaash 0 Jun 25 11:43 testFile_027.txt
-rw-r--r-- 1 iamyaash iamyaash 0 Jun 25 11:43 testFile.txt
- Change
umask to 077 and create a directory:
iamyaash@pi5:~/umask $ ll
total 0
iamyaash@pi5:~/umask $ umask
0022
iamyaash@pi5:~/umask $ mkdir testDir022 && ll
total 4.0K
drwxr-xr-x 2 iamyaash iamyaash 4.0K Jun 25 11:48 testDir022
iamyaash@pi5:~/umask $ umask 077 && umask && mkdir testDir077 && ll
0077
total 8.0K
drwxr-xr-x 2 iamyaash iamyaash 4.0K Jun 25 11:48 testDir022
drwx------ 2 iamyaash iamyaash 4.0K Jun 25 11:48 testDir077
What is chgrp?#
The chgrp is a Linux command that changes the group ownership of the files and directories.
Essential Commands#
| Commands | Description |
|---|
chgrp groupName directoryName | Change the group ownership of a file |
chgrp -R groupName directoryName | Change the group ownership of both the directory and the contents inside it |
Subcommands#
| Commands | Description |
|---|
chgrp -R | Recursive Operations |
chgrp -v | Verbose output details |
chgrp --reference=referenceFile/Dir targetFile | To change the group ownership like the referenced file/directory |
Example#
- List your groups
- Change the group of a file/directory
chgrp groupName fileName.txt #file
chgrp groupName dirName/ #directory only, not the contents inside it
chgrp groupName -R dirName/ #directory and it's content