Changing file permissions on an HFS+ filesystem

Question

I ran the command fdisk -l to find out what my external drive is formatted to, I found out it's uses GPT partitions and the filesystem is HFS+.

When I try and create a new folder on the external drive I receive the following message:

chmod: changing permissions of 'file_name/': Read-only file system

If I run mount this is the output:

/dev/sda1 on / type ext4 (rw,errors=remount-ro)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/cgroup type tmpfs (rw)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
none on /run/user type tmpfs (rw,noexec,nosuid,nodev,size=104857600,mode=0755)
none on /sys/fs/pstore type pstore (rw)
systemd on /sys/fs/cgroup/systemd type cgroup (rw,noexec,nosuid,nodev,none,name=systemd)
gvfsd-fuse on /run/user/1000/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,user=dev)
/dev/sdc2 on /media/dev/andre backup type hfsplus (ro,nosuid,nodev,uhelper=udisks2)
/dev/sde2 on /media/dev/andre_clients type hfsplus (ro,nosuid,nodev,uhelper=udisks2)

So now I ran umount /dev/sde2 and unplugged the device then reconnected the device and ran the command dmesg | tail and got this information back:

[429154.613747] sd 14:0:0:0: [sde] Assuming drive cache: write through
[429154.615995] sd 14:0:0:0: [sde] Test WP failed, assume Write Enabled
[429154.616993] sd 14:0:0:0: [sde] Asking for cache data failed
[429154.616997] sd 14:0:0:0: [sde] Assuming drive cache: write through
[429154.669277]  sde: sde1 sde2
[429154.671369] sd 14:0:0:0: [sde] Test WP failed, assume Write Enabled
[429154.672742] sd 14:0:0:0: [sde] Asking for cache data failed
[429154.672747] sd 14:0:0:0: [sde] Assuming drive cache: write through
[429154.672751] sd 14:0:0:0: [sde] Attached SCSI disk
[429157.047244] hfsplus: write access to a journaled filesystem is not supported, use the force option at your own risk, mounting read-only.

Answer 1

I managed to find the answer with the help of @polym

Here is my findings on fixing this error:

Note:

It seems you need to mount a hfsplus as write/read, which is a bit problematic, because of it's journal function.

However, you can mount it as write/read as seen here and here.

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The problem is that /dev/sde2 is mounted read only, according to the ro flag in the parentheses in the last line:

/dev/sde2 on /media/dev/andre_clients type hfsplus (ro,nosuid,nodev,uhelper=udisks2)

Therefore you can't change anything on this disk.

Remount it as read+write rw:

sudo mount -o remount,rw /partition/identifier /mount/point

In your case:

sudo mount -o remount,rw /dev/sde2 /media/dev/andre_clients

Before you do that, though, make sure you mount the right partition identifier by using dmesg | tail, e.g.:

[25341.272519] scsi 2:0:0:0: Direct-Access     [...]
[25341.273201] sd 2:0:0:0: Attached scsi generic sg1 type 0
[25341.284054] sd 2:0:0:0: [sde] Attached SCSI removable disk
              [...]
[25343.681773]  sde: sde2

The most recent sdX: sdXX line gives you a hint on which partition identifier (the sdXX one) your device connection is identified with.

You can also check which dev your device is connected to, by doing

ll /dev/disk/by-id/

This will give you all symbolic links of the device and it's partitions:

lrwxrwxrwx 1 root root   9 Jul 22 16:02 usb-manufacturername_*serialnumber* -> ../../sdb
lrwxrwxrwx 1 root root  10 Jul 22 16:02 usb-manufacturername_*serialnumber*-part1 -> ../../sdb1

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Answer 2

You're mixing differents things: partition table, partitions, filesystems, permissions, etc…

GPT is a type of partition table, which describes partitions on the disk. Those partitions contain a formatted filesystem. Like the error message says, it's the file system which cannot be written, either because it's mouted read-only (mount command will show the flag ro) or because it's not supported. For example by default you cannot write to a journalised HFS+ partition.

Paste the output of the mount command to allow us to know the file system and the mount options on that partition.