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-   -   bash script prob: how can i tell the script that a 'dd' has finished? (https://www.linuxquestions.org/questions/linux-general-1/bash-script-prob-how-can-i-tell-the-script-that-a-dd-has-finished-52992/)

Frustin 04-02-2003 02:51 AM
bash script prob: how can i tell the script that a 'dd' has finished?
 
I want to set up a script that runs my progress bar until my dd (256Meg image) has completed.

i tried something like

# copy the image to /dev/hdc1
dd if=./myimage.img of=/dev/hdc1 &

# this is supposed to run until most recently invoked process i.e.
# the image i am dd'ing has finished (returned false).

until %% #this is line 5 see error message below
do
/root/my/progress/script
done

when i run the script it clearly starts up the coping (its in the process list) of the image but doesnt enter the loop, anyway this gives me a error message like so:

./testscript: line 5: fg: no job control

Mik 04-02-2003 04:39 AM
The %% can only be passed to commands which accept a job id. You should probably read the bash man page or the advanced bash scripting guide. They both explain a little more about this.

Here is a simple script which I just wrote which waits for a command to complete and shows it's progress by displaying a period every second. It uses $! which contains the pid of the last process started in the background. And uses the ps command to see if this process is still running.

Code:
#!/bin/bash

sleep 10 &

echo -n waiting
while [ -n "`ps --no-headers $!`" ]
do
  echo -n .
  sleep 1
done

echo
echo done

Frustin 04-02-2003 05:34 AM
thanks very much for that. I had a look at the man page regarding that --no-headers option.

sorry i made a typo in my code. works fine thanks a lot.


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