Test whether shell script will have permission to write to a folder?

Scripting Forums AppleScript | Mac OS X
#1

I have a script that runs a command-line utility that creates a file. This fails if the folder where the file is to be created is outside the user’s own folder structure (e.g. in a folder with a name like /Files/Notes). Is there a simple way that a script can test whether it will be able to write to that folder, and warn the user in advance?

Thanks for any help with this.

#2

I suppose the simple answer to my own question is:

do shell script "echo hello > /possibly/forbidden/folder/hello.txt"

and test for an error message. If there is no error, then clean up with:

do shell script "rm /possibly/forbidden/folder/hello.txt"

If there’s anything more direct than this, I’ll be glad to hear about it.

#3

This should do it. According to the docs, it determines “whether the current process (as determined by the EUID) can write to the resource”:

use AppleScript version "2.4" -- Yosemite (10.10) or later
use framework "Foundation"

set thePath to "/System" -- whatever
set theURL to current application's |NSURL|'s fileURLWithPath:thePath
set {theResult, canWrite} to theURL's getResourceValue:(reference) forKey:(current application's NSURLIsWritableKey) |error|:(missing value)
canWrite as boolean
#4

Shane,

Thank you. That does the job perfectly.

For the sake of long-term beginners like me, the next lines of the script should be something like:

if not canWrite then
		display dialog "Apple won't let me work with the folder that contains your file." 
		error number -128
end if

Thanks again!

#5

You could also make your shell script more complete :slight_smile:

set shellScript to "if [[ -w /Library ]]
then
	#execute command line utility
	
	exit 0
else
	#we don't have write permission
	echo \"Cannot write to folder\"
	exit 1
fi"


try
	do shell script shellScript
on error ErrMsg number ErrNr
	if ErrNr = 1 then
		display dialog "Apple won't let me work with the folder that contains your file."
		error number -128
	end if
end try
#6

Very nice indeed!