Read/write file to LM5 connected USB

[admin]

First, reboot your LM. Since you have tried different scripts your mount table is probably messed up. Second, make sure your flash drive is formatted as FAT or FAT32 (but not exFAT). Run this script once, then go to System Config > Status > System Status. In Partitions tab you should see that /dev/sda1 or similar is mounted under /mnt. Then you can use io.writefile('/mnt/myfile.txt', 'test') to write something onto USB drive.

Code:

devs = io.ls('/sys/class/block/')
table.sort(devs)
for _, dev in ipairs(devs) do
  if dev:match('^sd%a%d$') then
    part = dev
    break
  elseif not devn and dev:match('^sd%a$') then
    devn = dev
  end
end

part = part or devn
if part then
  os.execute('umount -f /mnt 2>&-')
  res, stat = io.readproc('mount /dev/' .. part .. ' /mnt 2>&1')
  if stat == 0 then
    alert('USB mount OK')
  else
    alert('USB mount failed: ' .. tostring(res))
  end
else
  alert('No valid USB devices found')
end