#!/bin/bash
log=running_setup.txt
sudo_stat=sudo_status.txt

echo "========= running script $$ ========"
echo $$ >> $sudo_stat
trap 'rm -f $sudo_stat >/dev/null 2>&1' 0
trap "exit 2" 1 2 3 15

sudo_me() {
 while [ -f $sudo_stat ]; do
  echo "checking $$ ...$(date)"
  sudo -v
  sleep 5
 done &
}


echo "=setting up sudo heartbeat="
sudo -v
sudo_me

echo "=running setup=" | tee $log
while [ -f $log ]
do
 echo "running setup $$ ...$(date) ===" | tee -a $log
 sleep 2
done

# finish sudo loop
rm $sudo_stat

$ ./do_it.sh
========= running script 6776 ========
=setting up sudo heartbeat=
[sudo] password for user:
=running setup=
checking 6776 ...Wed May  4 16:31:47 PDT 2011
running setup 6776 ...Wed May  4 16:31:48 PDT 2011 ===
running setup 6776 ...Wed May  4 16:31:50 PDT 2011 ===
running setup 6776 ...Wed May  4 16:31:52 PDT 2011 ===
checking 6776 ...Wed May  4 16:31:53 PDT 2011
running setup 6776 ...Wed May  4 16:31:54 PDT 2011 ===
<ctrl-c>  (cleans up files, then exits)

$ ./sudoping.sh
Starting background sudo ping...
Password:
ok
Sudo ping!
Sudo pinging in PID = 47531
Sudo ping!
Sudo ping!
Sudo ping!
Sudo ping!
Goodbye!
Stopping sudo ping in PID = 47531

$ ./sudoping.sh
Starting background sudo ping...
ok
Sudo ping!
Sudo pinging in PID = 47599
Sudo ping!
^CStopping sudo ping in PID = 47599

-v          If given the -v (validate) option, sudo will update the user's time stamp,
               prompting for the user's password if necessary.  This extends the sudo timeout for
               another 15 minutes (or whatever the timeout is set to in sudoers) but does not run
               a command.