CODEWITHSUNDEEP
rubylinuxprocess
Anand
Anand

Reputation: 10400

How can I listen to a running Linux process?

I was running a rake task as a separate process in my server and printing on STDOUT tracking the progress of that script.

While in the SSH connection, my internet connection reset. When I reestablished the connection to the server, I found that the process was still running. I want to listen to its STDOUT ouput. I have the process id.

How can I do that?

Upvotes: 2

Views: 532

Answers (4)

Markus T
Markus T

Reputation: 1594

strace  -p $pid_of_process_you_want_to_see_stdout_of 2>&1| sed -re 's%^write\(1,[[:blank:]](.*),[[:blank:]]*[0-9]+\)[[:blank:]]*=[[:blank:]]*[0-9]+%\1%g'

Stolen from here:

https://superuser.com/questions/473240/redirect-stdout-while-a-process-is-running-what-is-that-process-sending-to-d

Upvotes: 0

John Zwinck
John Zwinck

Reputation: 249093

retty should do what you want. http://pasky.or.cz/dev/retty/

Upvotes: 1

Hugh
Hugh

Reputation: 8932

I don't have a Linux VM handy to test this on, but you might be able to connect to the process with gdb, open(2) a new file descriptor to use as standard output, then dup2(2) that to fd 1.

Upvotes: 0

Wayne Conrad
Wayne Conrad

Reputation: 107959

For the future, consider screen. This wonderful little tool can hold a large number of virtual terminals and let you easily switch from one to the next (without even using the mouse), but what's best, is if you get disconnected the virtual terminals live on until you reconnect and recover the screen session.

To start a screen session:

screen

To detach a screen session on purpose so you can disconnect and leave it running:

C-a C-d

To reattach your detached screen session

screen -dr

There's a whole lot more to it, but that's enough to get you started.

Upvotes: 1

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