Problem

Trying to delete files from a USB drive results in:

rm: cannot remove '<file>': Read-only file system

Root Cause

This is NOT a file permission issue.

The filesystem (USB) was mounted as read-only (ro) due to:

  • Filesystem corruption
  • Unsafe removal
  • I/O errors

Step 1 — Confirm Read-Only Mount

mount | grep KINGSTON

If you see:

(ro, ...)

→ The filesystem is read-only.

Step 2 — Exit the Mounted Directory

cd /

Step 3 — Check Processes Using the Mount

lsof | grep KINGSTON

If needed:

fuser -km /media/enkiel/KINGSTON

Step 4 — Unmount the USB

sudo umount /dev/sdb1

If it fails:

sudo umount -l /dev/sdb1

Step 5 — Repair Filesystem

sudo fsck.vfat -a /dev/sdb1

If needed:

sudo fsck.vfat -r /dev/sdb1

Step 6 — Remount

udisksctl mount -b /dev/sdb1

Verify:

mount | grep KINGSTON

Expected:

(rw, ...)

Step 7 — Delete Files

Single file:

rm /media/enkiel/KINGSTON/DCIM/Camera/<filename>

find /media/enkiel/KINGSTON/DCIM/Camera -mindepth 1 -delete

Alternative:

rm -rf /media/enkiel/KINGSTON/DCIM/Camera/*

Step 8 — Verify Disk Usage

df -h /media/enkiel/KINGSTON

Optional — Check Logs

sudo dmesg | tail -50

Final Advice

If this repeats:

  • Backup immediately
  • Reformat: 
    sudo mkfs.vfat /dev/sdb1
  • Replace the USB if errors persist