how to move background process to foreground

[batola]

Hi,

is it possible in bash to run one command in background and after it's done show output with less? While background process is running I should be able enter another commands.

What I have is this (sleep is only for simulation):

{({ ( tree / > tree.txt && sleep 2)  & } && wait && less tree.txt) &} && wait && fg &

Problem is that I don't know and I can't find how to move it to the foreground after completion.

What I want is:

1) redirect output from `tree` to tree.txt in background
2) wait while `tree` is running
3) show tree.txt with `less`

All those steps should be run in background and after 1st step is done 3rd step should be brought to foreground.

Thanks.

[karthi_27]

Use the command 'fg' to bring the background process to foreground.

[Cabhan]

As far as I know, you cannot.

By backgrounding a process, you are intentionally disassociating it from a terminal. Therefore, that process cannot possibly print anything to a terminal.

You could write a program to wait for the first to finish, but this program would need a terminal, so it could not be backgrounded, which would mean that you could not enter other commands.


On second thought, I suppose you could write a program that spawns a child that runs the command you want and then less. The initial program could exit immediately, freeing the terminal for input, but the child would still output to the terminal, so "less" could run. However, the terminal would behave very strangely once "less" was invoked (I don't believe that "less" would receive any input), and the program is awfully complicated for what you want.

So as far as I know, this can't really be done.

[drl]

Hi, batola.

Welcome to the forums.

Your code and outline seem to be your apparent solution to a problem.

Often, other solutions may be revealed by stepping back and stating the problem that you are trying to solve ... cheers, drl