Running a script with top command in the background

Question

I have a script that basically prints that output of top -n1 to a file every second

In its simplest form:

while [ 1 ] ; do
   top -n1
   sleep 1
done

If I run my secript like:

./my_script.sh > out.log

it runs fine

If I run it in the background:

./my_script.sh > out.log &

Then it give me Stopped(SIGTTOU) error. From other Q/As I found that top is trying to read from the stdin, and when run in the background there is no stdin.

How can I achieve logging of top into a file as a background task?

@melpomene No, is that inside the script? - I am not quite sure where to put that code snippet? - thanks :) — code_fodder, Oct 03 '19 at 12:28

CoolZero · Accepted Answer · 2019-10-03T12:35:00.027

2

You need to write top to file, and that in a loop..

#!/bin/bash
while [ 1 ] ; do
   top -b -n 1 > top.txt
   sleep 1
done

or

#!/bin/bash
while :
do
  top -b -n 1 > top.txt
  sleep 1
done

edited Oct 03 '19 at 12:35

answered Oct 03 '19 at 12:28

CoolZero

109
7

1

Surely you mean `#! /bin/bash` :p – Bayou Oct 03 '19 at 12:30
`[ 1 ]` is weird way to write `true`. – melpomene Oct 03 '19 at 12:32
1

@code_fodder Then why not just use `:`? Can't get much shorter than `while :; do ...`. Also, `true` is actually shorter than `[ 1 ]` by one character. – melpomene Oct 03 '19 at 12:34
@melpomene damn... even better :)) – code_fodder Oct 03 '19 at 12:36
Or the equivalent of while true: `until false; do stuff; done` – Bayou Oct 03 '19 at 12:44

Running a script with top command in the background

1 Answers1