start and monitoring a process inside shell script for completion - bash

Question

I have a simple shell script whose also is below:
#!/usr/bin/sh
echo "starting the process which is a c++ process which does some database action for around 30 minutes"
#this below process should be run in the background
<binary name> <arg1> <arg2>
exit
Now what I want is to monitor and display the status information of the process.
I don't want to go deep into its functionality. Since I know that the process will complete in 30 minutes, I want to show to the user that 3.3% is completed for every 1 min and also check whether the process is running in the background and finally if the process is completed I want to display that it is completed.
could anybody please help me?

Answer 1

The best thing you could do is to put some kind of instrumentation in your application,
and let it report the actual progress in terms of work items processed / total amount of work.
Failing that, you can indeed refer to the time that the thing has been running.
Here's a sample of what I've used in the past. Works in ksh93 and bash.
#! /bin/ksh
set -u
prog_under_test="sleep"
args_for_prog=30
max=30 interval=1 n=0
main() {
($prog_under_test $args_for_prog) & pid=$! t0=$SECONDS
while is_running $pid; do
sleep $interval
(( delta_t = SECONDS-t0 ))
(( percent=100*delta_t/max ))
report_progress $percent
done
echo
}
is_running() { (kill -0 ${1:?is_running: missing process ID}) 2>& -; }
function report_progress { typeset percent=$1
printf "\r%5.1f %% complete (est.) " $(( percent ))
}
main

Answer 2

If your process involves a pipe than http://www.ivarch.com/programs/quickref/pv.shtml would be an excellent solution or an alternative is http://clpbar.sourceforge.net/ . But these are essentially like "cat" with a progress bar and need something to pipe through them. There is a small program that you could compile and then execute as a background process then kill when things finish up, http://www.dreamincode.net/code/snippet3062.htm that would probablly work if you just want to dispaly something for 30 minutes and then print out almost done in the console if your process runs long and it exits, but you would have to modify it. Might be better just to create another shell script that displays a character every few seconds in a loop and checks if the pid of the previous process is still running, I believe you can get the parent pid by looking at the $$ variable then check if it is still running in /proc/pid .

Answer 3

You really should let the command output statistics, but for simplicity's sake you can do something like this to simply increment a counter while your process runs:
#!/bin/sh
cmd & # execute a command
pid=$! # Record the pid of the command
i=0
while sleep 60; do
: $(( i += 1 ))
e=$( echo $i 3.3 \* p | dc ) # compute percent completed
printf "$e percent complete\r" # report completion
done & # reporter is running in the background
pid2=$! # record reporter's pid
# Wait for the original command to finish
if wait $pid; then
echo cmd completed successfully
else
echo cmd failed
fi
kill $pid2 # Kill the status reporter