unix file permissions...
the host that i have been using and learning perl on automatically chmods all files to 755, but now im starting to write scripts that will work universally but i dont fully understand these permissions.
does read/write mean the file can be read/written to, or the file can read/write to other files?
what is the difference between owner and group permissions?
If i have a count file that just stores a counter number, does that file need write permissions, or does the script writing to it need write permissions? owner, group or public?
I have looked and i cannot find a unix permissions tuit that makes much sense. If you know of one please post it.
Thanks!
Orpheus posted this at 08:12 — 23rd June 2000.
They have: 568 posts
Joined: Nov 1999
I dont pay any attention to user, group, other.
I just use numbers, like on my linux pc
755 exec
(just a little humour, no offense intended)
777 write
666 worship sata... errr read.
anti posted this at 10:15 — 23rd June 2000.
They have: 453 posts
Joined: Jan 1999
Each "normal" file has 9 flags.
3 for the owner of the file
3 for users in the same group as the owner
3 for others
the flags are:
r - for reading the file/directory
w - for writing to the file/directory
x - for executing the file/cding through the dir
usually you encode the flags in an octal triplet.
ABC
A = owner-perm
B = group-perm
C = other-perm
r = 4
w = 2
x = 1
So if you want rwx for the user and r-x for all others (including groups) you get:
A = 4(r)+2(w)+1(x) = 7
B = C = 4(r)+1(x) = 5
-> 755
Actually you don't you use a permission triplet, but don't bother with the fourth number, that's really complicated ...
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