Write denied on exfat usb hdd mounted locallly

[Aragorn]

@andrewysk

i want
file permission: owner (rwx), group (r-x), other (—)
folder permission: owner (rwx), group (r-x), other (—)
How to calc ?

fmask and dmask are the bisected versions of the umask for files and directories respectively in the mount options for non-POSIX filesystems.

As for how to calculate the values, see the following two sections from my tutorial on POSIX permissions…

@Aragorn

For those of you who aren’t good with numbers, here’s a little table with the possible permissions values within a single triad. Note that some of these permissions below are nonsensical from the practical standpoint, but they are shown just for the sake of being able to understand how a permissions mask translates into an octal value.

PERMISSIONS           BINARY VALUE    OCTAL VALUE

    ---                  000              0
    --x                  001              1
    -w-                  010              2
    -wx                  011              3
    r--                  100              4
    r-x                  101              5
    rw-                  110              6
    rwx                  111              7

When it comes to file permissions, the most common way you’ll see these octal numbers being used is in reference to all three of the triads, i.e. user, group and others. A typical example for a system directory would be 755, which translates into drwxr-xr-x permissions. For non-executable files, a typical example would be 644, which translates to -rw-r--r--.

@Aragorn

UMASK

In UNIX systems, the command umask is used in combination with a three-digit octal number ─ one for each permissions triad ─ to determine the permissions that a new file or new directory must be created with, but in an inverse way, i.e. the octal number does not represent the permissions that the file or directory will be created with, but what octal value must be subtracted from 777 for directories and 666 for files. So a umask of 022 means that new directories will be created with a 755 (drwxr-xr-x) permissions mask, and new files with a 644 (-rw-r--r--) permissions mask.

Normally, the root account’s umask should always be 022 ─ notwithstanding the fact that the permissions on the root user’s home directory /root should always be set to 700 or 750 ─ and this is usually also the case for unprivileged user accounts, but personally, I prefer a umask of 077 for unprivileged user accounts, for reasons of privacy on systems with multiple unprivileged accounts.

The umask is commonly set in the shell’s configuration files ─ systemwide, this will be in /etc/login.defs, and individual users can set it in ~/.bashrc or ~/.zshrc, depending on what shell they use.