How can I use the root password provided by the user in my bash installation script - bash

Question

I'm trying to install a cronjob to run a bash shell script on a relative's machine. They will run the install and I can't access it remotely yet (that's what my script is for - but that's not the issue here). I use kdialog to request their root password and then want to use that to sudo various commands. My code below is failing by a) revealing the root p/w on the terminal and b) failing to pipe it to the various sudos. Help?
#!/bin/bash
kdialog --password "Please enter your root password to install theCronScript.sh and set up cron"
# Sanity checks =========================================╕
if test -z "$BASH" ; then
printf "$SCRIPT:$LINENO: please run this script with the BASH shell\n">&2
exit 192
fi
#========================================================╛
# Global variables=======================================╕
PW="$?"
THISDIR="$(pwd)"
GETIPFILE='theCronScript.sh'
CRONPERIOD='/15 * * * * '
TARGETCRONDIR='/etc/cron.hourly'
#========================================================╛
echo "hi"
# txt file exists check =================================╕
echo "Checking:"
if [ ! -f "$THISDIR/$GETIPFILE" ]; then #there's no file to install
kdialog --msgbox "I cannot find $GETIPFILE to upload\nPlease check attachments in recent e-mails from Greg and download $GETIPFILE to $THISDIR"
exit
else
if [ -f "$TARGETCRONDIR/$GETIPFILE" ]; then #the target already exists
kdialog --title "Replace or Keep" --warningyesno "A similar file already exists.\n Do you want to replace it (recommended)?\n(The original file will be saved with a different name _OLD)"
if [ $? = 0 ]; then # rename, then replace the existing file
#echo $PW is probably unneccessary beyond the first use but just in case...
RNGETIPFILE=$GETIPFILE'_OLD'
echo $PW | sudo -S mv $TARGETCRONDIR/$GETIPFILE $TARGETCRONDIR/$RNGETIPFILE #rename original file
echo $PW | sudo -S cp $THISDIR/$GETIPFILE $TARGETCRONDIR/$GETIPFILE #copy new version in
echo $PW | sudo -S chmod +x $TARGETCRONDIR/$GETIPFILE #
echo $PW | sudo -S crontab -l > mycron #write out current crontab
echo $PW | sudo -S echo $CRONPERIOD $TARGETCRONDIR >> mycron #echo new cron into cron file
echo $PW | sudo -S crontab mycron #install new cron file
rm mycron
$PW="" #clear password variable once it's no longer required
else # Don't replace, exit
exit
fi
else # Nothing to replace. Just copy it in
echo $PW | sudo -S "cp $THISDIR/$GETIPFILE $TARGETCRONDIR/$GETIPFILE" #copy new version in
echo $PW | sudo -S chmod +x $TARGETCRONDIR/$GETIPFILE # make sure it's executable
echo $PW | sudo -S crontab -l > mycron #write out current crontab
echo $PW | sudo -S echo $CRONPERIOD $TARGETCRONDIR >> mycron #echo new cron into cron file
echo $PW | sudo -S crontab mycron #install new cron file
rm mycron
$PW="" #clear password variable once it's no longer required
fi
fi
exit 0
#========================================================╛

Answer 1

One option is to ask for the password directly in the sudo command via an external GUI. From the sudo manpage:
-A, --askpass
Normally, if sudo requires a password, it will read it from the user's terminal. If the -A (askpass) option is specified, a (possibly graphical)
helper program is executed to read the user's password and output the password to the standard output. If the SUDO_ASKPASS environment variable is
set, it specifies the path to the helper program. Otherwise, if sudo.conf(5) contains a line specifying the askpass program, that value will be
used. For example:
# Path to askpass helper program
Path askpass /usr/X11R6/bin/ssh-askpass
If no askpass program is available, sudo will exit with an error.
if sudo is caching credentials, it will only ask for this password once. One way I use to get this cached would be, having no side effects other than caching the password:
export SUDO_ASKPASS=/usr/bin/ssh-askpass
sudo --askpass true
Depending on what distro you're running, ssh-askpass may be somewhere else. There is an example on StackExchange on how you might use kdialog to get the password for the sudo askpass. For reference, here is the script:
$ cat myaskpass.sh
#!/bin/bash
kdialog --password "Please enter your password: "
exit 0
And how you would use it:
export SUDO_ASKPASS=/path/to/myaskpass.sh
sudo --askpass true