utility to convert between permission list and octal chmod format?

$ ls -l foo

-rw------- 1 me staff 0 <date> <time> foo

$ stat -f %Lp foo

600

Have you considered Batchmod?

http://www.lagentesoft.com/batchmod/

I understand your question. I don't know of a prepackaged way to convert between mode strings and octal modes. My point was that you don't necessarily have to. If you want to set an octal mode, just set it -- you don't have to convert it first.

Here: http://permissions-calculator.org

Open the AppleScript Editor in the /Applications/Utilities/ folder and run:

set the_string to "4775"

set new_string to "-"

if (count the_string) is 4 then

set the_list to items 2 thru 4 of the_string

repeat with this_char in the_list

if (this_char as number) is in {4, 5, 6, 7} then

set new_string to new_string & "r"

else

set new_string to new_string & "-"

end if

if (this_char as number) is in {2, 3, 6, 7} then

set new_string to new_string & "w"

else

set new_string to new_string & "-"

end if

if (this_char as number) is in {1, 3, 5, 7} then

set new_string to new_string & "x"

else

set new_string to new_string & "-"

end if

end repeat

set new_string to items of new_string

if (item 1 of the_string as number) is in {4, 5, 6, 7} and item 4 of new_string is "x" then set item 4 of new_string to "s"

if (item 1 of the_string as number) is in {4, 5, 6, 7} and item 4 of new_string is "-" then set item 4 of new_string to "S"

if (item 1 of the_string as number) is in {2, 3, 6, 7} and item 7 of new_string is "x" then set item 7 of new_string to "s"

if (item 1 of the_string as number) is in {2, 3, 6, 7} and item 7 of new_string is "-" then set item 7 of new_string to "S"

if (item 1 of the_string as number) is in {1, 3, 5, 7} and item 10 of new_string is "x" then set item 7 of new_string to "t"

if (item 1 of the_string as number) is in {1, 3, 5, 7} and item 10 of new_string is "-" then set item 7 of new_string to "T"

return new_string as string

end if

if (count the_string) is 10 then

set new_number to 0

considering case

if item 2 of the_string is "r" then set new_number to new_number + 400

if item 3 of the_string is "w" then set new_number to new_number + 200

if item 4 of the_string is "x" then set new_number to new_number + 100

if item 4 of the_string is "s" then set new_number to new_number + 4100

if item 4 of the_string is "S" then set new_number to new_number + 4000

if item 5 of the_string is "r" then set new_number to new_number + 40

if item 6 of the_string is "w" then set new_number to new_number + 20

if item 7 of the_string is "x" then set new_number to new_number + 10

if item 7 of the_string is "s" then set new_number to new_number + 2010

if item 7 of the_string is "S" then set new_number to new_number + 2000

if item 8 of the_string is "r" then set new_number to new_number + 4

if item 9 of the_string is "w" then set new_number to new_number + 2

if item 10 of the_string is "x" then set new_number to new_number + 1

if item 10 of the_string is "t" then set new_number to new_number + 1001

if item 10 of the_string is "T" then set new_number to new_number + 1000

end considering

return new_number

end if

(83221)

In searching around I just found this widget, which might be useful as well, and more convenient in that it will run in the dashboard: http://www.apple.com/downloads/dashboard/networking_security/unixpermissioncalcu latorwidget.html

Is there a reason you care?

chmod accepts rxw letters, no octal needed. For example the following sets the user permissons rwx, and the group and other permissions to rx (aka 755, but I did not need 755 to do this).

chmod u=rwx,go=rx file

You can also use + or - instead of = to add/remove permission bits, all using letters and no octal.

See "man chmod"

I suppose I'm contiually surprised at how retrograde and computer-geekish documentation is in persisting to use octal permission codes in configuration instructions. Mind you, I'm not uncomfortable with octal:

Would you prefer decimal? 🙂

indeed, the second computer I ever programmed took all its instructions in octal (punched onto a paper tape).

PDP-8?

As I recall the first Unix was implemented on a PDP-7, and the PDP-11 where it became popular often used octal (most likely a carry over from the PDP-8 days). And since 3 permisson bits fix an octal character and that early Unix utilities had to fit in 56K of memory and data with an 8K stack, the first chmod did not have a symbolic input form, so octal made a lot of sense.

And changing the command API has a tendency to break other programs and scripts, so once established, they tend not to change over the years, just add non-conflicting options/features.

This machine was quite a step down from the first computer I ever programmed, a Univac I (in assembler or numeric code, don't recall which).

As a former UNIVAC employee, I thank you for your support 🙂