Question

I am using mkdir in a php script to make file3 in directory /file/file2/file3. I use permission 777 but the file always looks like dr----x--t 2 admin admin 4096 Jul 1 19:26 file3 once it is made. I am running Centos 5 64bit. file2 is permission drwxrwxrwx 16 root root 4096 Jul 1 19:26 file2 already. Anyone have any ideas why this is?

mkdir("/file1/file2/file3",777);

Answer 1

You want to use 777 octal, not decimal:

mkdir ("/file1/file2/file3", 0777);

777 decimal turns out to be 1411 octal which will give you the bitmask 1 100 001 001 which is why you’re getting those “strange” permissions. The standard set (last three segments) gives you r----x--x and the first segment modifies the world permissions to t (the sticky bit).

Also keep in mind that mkdir is subject to your umask setting and may not give you the permissions you ask for (your umask setting gets “removed” from the permissions you ask for to give you the actual permissions). See here for details, including how to avoid the problem.

You’re better off using mkdir to create the directory then chmod (which isn’t affected by your umask setting) to change the permissions.