Most of my career to this point has revolved around Windows, with just enough
Linux/Unix experience to get around a system and REALLY goof things up. So, I
wanted to post something I put together from multiple sources to better explain
how the whole permissions thing works on files in Unix.
Unix Permissions
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# rwx explaination
read (r) 4
write (w) 2
execute (x) 1
# numeric calculation of permissions
7 = 4+2+1 (r-w-x)
6 = 4+2 (r-w)
5 = 4+1 (r-x)
4 = 4 (r)
3 = 2+1 (w-x)
2 = 2 (w)
1 = 1 (x)
# EXAMPLE - change permissions on a file
chmod 755 somefile.txt
# EXAMPLE - take/give ownership of a file
chown somefile.txt
There are some nuances in syntax from one Unix flavor to another, but these should give an
idea of what it all means.
NOTE 1: Root has full permission and access to ALL files.
NOTE 2: The creator of a file has full permission and access to THAT file.