How to launch a job in a shell which will persist even if the shell which launches it terminates

Question

How do I lauch a job in a Linux shell, so that even if the shell which launches it terminates, this job will still persist?

More specifically, I am trying to run strace on a process. It runs perfectly if I do it in a terminal. However, I want to do it in a remote shell which will stop as soon as all the commands have been executed. "strace -p pid &" doesn't have any effect because when the shell stops, the background job also gets killed.

How should I do it?

nohup seems to be thing I am looking for. However, ssh user@remote_machine script_name doesn't seem to have any effect neither. In the script I have "nohup strace -p pid"

Thanks a lot!

Answer 1

Nohup and Screen can be used to run a command even if the session is disconnected or the user logs out. I use them both, but “Screen” is better.

nohup ./<script_name> &

How to use screen?

creat a task:

$ screen -S task

Execute a command in the task window，if your task not finished, use

$ Ctrl+a+d
to save the task. It will show the following info:
[detached]

if your task has been finished, use “exit” to exit screen:

    $ exit

[screen is terminating]

You can use screen -ls to find any screen info:

$ screen -ls
There is a screen on:
10000.task (Detached)

Use “screen -r” to recover the task:

$ screen -r 10000

Answer 2

you could use "screen"! Usage:

screen [Enter]
enter your command
[Ctrl] + [A] + [D(Detach)]

Your task continues running. If you want to go back to it just type in:

screen -r

or

screen -r -d (to detach old sessions)

Answer 3

In addition of other answers, you may want to use the batch(1) command (perhaps remotely thru ssh), like e.g.

  batch << ENDBATCH
    strace -p 1234 -o /tmp/trace.file
  ENDBATCH