Quick Look At Linux File Permissions

Examples

_rw-rw----

• Owner can read/access the file.

• Owner can write/change/delete the file.

• Owner can not execute file

• Group can read/access the file

• Group write/change/delete the file.

• Group can not execute file

• All Users has no permissions

drw-rw-rw

• Owner can read/access the directory

• Owner can write/change/delete the directory

• Group can access the directory

• Group write/change/delete the director

• All Users can access the directory

• All Users can write/change/delete the directory

lkrw-rw-rw

• Owner can read/access the file/directory the symbolic link points to

• Owner can write/change/delete the file/directory the symbolic link points to

• Group can access the file/directory the symbolic link points to

• Group write/change/delete the file/directory the symbolic link points to

• All Users can access the file/directory the symbolic link points to

• All Users can write/change/delete the file/directory the symbolic link points to

I created a symbolic link to helloWorld to demonstrate this.

By entering ls -l helloWORLD at the command prompt the following information was displayed.

As you can see the first flag is the small letter L. Also note the -> points to the path of the actual file hellowWorld the symbolic link file named Link to helloWORLD is linked to.

Other Special Permissions

s - setuid and setgid (short for "set user ID upon execution" and "set group ID upon execution", respectively) The s does not display in the Special Permissions Flag section but instead display in the r of the owner or group section.

t - sticky bit permission. The t does not display in the Special Permissions Flag section but instead display in the x of the owner or group section.

For more in depth study on the Linux/Unix file permissions see:

• • Understanding Linux File Permissions on Linux.com

  • Setuid on Wikipedia

  • Traditional Unix Permissions on Wikipedia