Skip to content

Instantly share code, notes, and snippets.

@zaius
Created January 16, 2011 23:29
Show Gist options
  • Save zaius/782263 to your computer and use it in GitHub Desktop.
Save zaius/782263 to your computer and use it in GitHub Desktop.
How to redirect a running process output to a file and log out
ctrl-z
bg
touch /tmp/stdout
touch /tmp/stderr
gdb -p $!
# In GDB
p dup2(open("/tmp/stdout", 1), 1)
p dup2(open("/tmp/stderr", 1), 2)
detach
quit
# Back in shell
disown
logout
@thomasluce
Copy link

I've not seen it done quite like this before. I like it!

It might be a bit cleaner with something like nohup $you_command_and_arguments_here 2>/tmp/stderr 1>/tmp/stdout to avoid the overhead of all the ptrace's that go on in gdb. Also, disown's implementation is defined to be shell-specific (in other words, do what works for your shell), whereas nohup uses system-level commands to abandon it's parent, so you are less likely to have strange side-effects if you try it on a non-bash shell.

@zaius
Copy link
Author

zaius commented Jan 17, 2011

Yeah it's definitely cleaner to do it that way, if you're organized :) I would make it even a simpler and just run it in screen or tmux. Though I know I regularly start long-running tasks before realizing how long they are going to take, so this is a quick hack to get around it.

@ogier
Copy link

ogier commented Jan 17, 2011

Thomas, I think you missed the point of the gist. This makes sense if you have a process already running and later realize you need to disown it without losing its output. I for one run into this problem often and I really like this solution.

@nnutter
Copy link

nnutter commented Jan 17, 2011

This was linked on Hacker News and in the comments there julian37 pointed out that someone created a bash script to do this called "Dupx".
http://www.isi.edu/~yuri/dupx/

Edit: And of course, thank you to bringing this tool to my attention. Very useful.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment