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Antitribu
Asked: 2009-10-15 03:31:55 +0800 CST

What happens to a deleted file still subject to redirection on linux?

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If a log file such as nohup.out is deleted in Linux while it is still the subject of a running job (and further input) what happens to the data?

eg

script.sh

#!/bin/bash
while [ 1 ]
do
  fortune
done

then...

# nohup ./script.sh &

This outputs the log to nohup.out by default.

Or even

# ./script.sh > nohup.out &

The question is; if nohup.out is deleted what happens? Is the file really gone assuming the job continues? What happens if script.sh generates enough data to fill a disk? Does this create a de-facto state of redirection to /dev/null?

By way of background I have found a process started previously in this method that can not be restarted for an extended duration but prior to that maintenance window it is my estimation the disk will fill. The situation will be avoided in the future, I am just curious as to what happens to an unlinked file still subject to redirection.

linux

1 Answers

  1. Best Answer

    If a program still has a file handle open, what I believe will happen is that the file continues to exist. It disappears from your directory listings and looks gone but until the last file handle is closed the file continues to grow.

    This is why people will have huge files on the filesystem and get errors, find an errant file that is huge, delete it, and still have huge disk space listings but cannot find the file anymore. It's there. Just not quite visible. Use lsof to find the application holding the file handle and kill/close the application then the space is reclaimed.

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