How to remove "dead.letter" File which left no free space in root directory
If you have removed it and the space still isn't freed, then it means a process has a file handle opened on it.
Try and find the PID of the process using, for instance:
for process in /proc/[0-9]*; do for fd in $process/fd/*; do file=$(readlink -f $fd) if [ "$file" = "/root/dead.letter" ]; then echo $process fi donedoneThen kill it/them.
You know about lsof (http://linux.die.net/man/8/lsof) ?
In this case:
sudo lsof /root/dead.letterThis prints out info's about the process having the file open. You still have to kill that process.
If the above script does not work, One can just think of the processes which might be having the handle to such files occupying space in root or home directory.
Kill such processes and the disk space will be freed
You can use (ps -ef | grep process_name) to find out the process id.