It's different accounts.
How would you expect safety from your account, if everyone had the permission to delete your home directory?
You do not have the w
permission to delete someone other's home directory by default, except if they chmod +w
it.
Here are the different permissions, and an example (-rwxr-x---
/rwxrx
):
+-+-+-+-+
|+|u|g|o|
+-+-+-+-+
|r|1|1|1|
+-+-+-+-+
|w|2|2|2|
+-+-+-+-+
|x|4|4|4|
+-+-+-+-+
|*|7|5|0|
+-+-+-+-+
It goes like this:
1 + 2 + 4 = 7
,
1 + 4 = 5
,
0 = 0
, so
750
, i.e. an ideal permission system. The owner (
u
in this case) can read, write and execute the file, the owner's group (
g
in this case) can read and execute, and anyone other (
o
in this case) cannot do anything. This is the legendary:
u: current user (User)
g: current user's groups (Groups)
o: not current user's groups (Others)
r: read permission (Read)
w: write permission (Write)
x: execute permission (X-ecute)
.