Issue
When using nohup the output of a script is buffered and only gets dumped to the log file (nohup.out) after the script has finished executing. It would be really useful to see the script output in something close to real-time, to know how it is progressing.
Is there a way to make nohup write the output whenever it is produced by the script? Or, since such frequent file access operations are slow, to dump the output periodically during execution?
Solution
There's a special program for this: unbuffer! See http://linux.die.net/man/1/unbuffer
The idea is that your program's output routines recognize that stdout is not a terminal (isatty(stdout) == false), so they buffer output up to some maximum size. Using the unbuffer program as a wrapper for your program will "trick" it into writing the output one line at a time, as it would do if you ran the program in an interactive terminal directly.
Answered By - John Zwinck