cannot delete file, Read-Only filesystem
 

i have a file a.txt i created on a external hdd. I wanted to delete it, but it complained that it is the "Read-Only filesystem",

So I tried "chomod 755 a.txt", it still complained the same thing.
I don't understand that i created the file, but cannot monify it?

is it has to do something with the external hhd has a ext_3 filesystem?

Maybe you mounted the filesystem read only. Try remounting it read-write.

works
 

got it. it is because i forgot to include the filesystem
tried $mount -t ext3, then everything just works. :)