I have three main partitions on my disc /dev/sda:

/dev/sda1            2048   117186559    58592256   83  Linux
/dev/sda2       117186560   128905215     5859328   82  Linux swap / Solaris
/dev/sda3   *   128905216   324216831    97655808    7  HPFS/NTFS/exFAT
/dev/sda4       324216832  1250263039   463023104    b  W95 FAT32

/dev/sda3 is a Windows 7 partition and /dev/sda4 is a FAT32 partition where I keep my data. My problem is that yesterday I can't write on /dev/sda4 and when I tried to change the file permissions I get an error:

$ sudo chmod 777 /media/fourat/74A7-A44E/
chmod: changing permissions of ‘74A7-A44E/’: Read-only file system

mount 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=fourat)
/dev/sda4 on /media/fourat/74A7-A44E type vfat (rw,nosuid,nodev,uid=1000,gid=1000,shortname=mixed,dmask=0077,utf8=1,showexec,flush,uhelper=udisks2)

Please help. Thanks

SOLVED: thanks to mikewhatever
Remounting the partition with

sudo mount -o remount,rw /dev/sda4
  • There's nothing in your question that shows us the location of '74A7-A44E'. Please update your question with the output of mount and where the directory you cannot change permissions of actually is. – Marcin Kaminski Jan 11 '15 at 19:05
  • Are you trying to apply chmod command on a file that exists on USB? – Wolverine Jan 11 '15 at 19:15
  • 3
    If a filesystem is read only, you need to re-mount it as rw - sudo mount -o remount,rw /dev/sda4, and not hammer it with chmod. The cause of such errors is usually filesystem corruption, so you'll need to check it for errors in Windows. – mikewhatever Jan 11 '15 at 19:17
  • If I'm not mistaken, FAT partitions don't have 'permissions'. Instead of chmod, you could just give your user permission to access the files with mount/fstab. – earthmeLon Jan 12 '15 at 18:37
  • 3
    Possible duplicate of How to make read-only file system writable? – Zanna Mar 7 '17 at 7:14

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.