request a password if not already saved, save password for later, and fetch it when necessary

gistfile1.txt

...
#  Prerequisites:
#
#  Accessing Password
#  To scan system directories the script needs elevated privileges. This means the user needs to input his password.
#  To automate the running of this script, it accesses the Keychain.app for the password.
#  For this to work, an entry has to be made in the Keychain.app manually:
#      security add-generic-password -s '<identifier>' -a '<userid>' -w '<passwd>'
#  or even better:
#      security add-generic-password -s '<identifier>' -a '<userid>' -w '<passwd>' -j 'comment' -T /usr/bin/security -D 'Scriptpassword'
#      where
#        -s some identifier like device name, url, alias, whatever
#        -a username to login into the device
#        -w password for the userid to log into the device
#        -j comment
#        -T binaries that are allowed access
#        -D type that better fits the use than "Internet Password"
#      ex: security add-generic-password -s $HOSTNAME -a $LOGNAME -w 'P455w0rd' -j 'for Script: create_change_protocol_10.14.sh' -T /usr/bin/security -D 'Scriptpassword'
...



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#  --------------------------------------------------------------------------------------------------------------------
#  FUNCTIONS
#  --------------------------------------------------------------------------------------------------------------------


#  ensure elevated privileges
fncEnsureElevatedPrivileges()
{
    #  check if users password has already been saved to 'Keychain Access.app' and if not, ask for it and save it
    #  remember: first set proper $HOSTNAME, then reboot, _then_ create keychain entry
    if ! security find-generic-password -s "${HOSTNAME%%.*}" -w 2>/dev/null | sudo -Svp "" 2>/dev/null
    then
        echo; read -rsp "${colorRedInverted}please enter the password for user $LOGNAME${colorNone}  " userPasswd; echo
    	echo -e "${statusInfo} create Keychain Access.app entry for user${colorNone}"
        security add-generic-password -s "${HOSTNAME%%.*}" -a "$LOGNAME" -w "$userPasswd" -j 'for Shellscripts' -T /usr/bin/security -D 'Scriptpassword'
    	echo "$userPasswd" | sudo -Svp ""
    fi
}
...



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#  --------------------------------------------------------------------------------------------------------------------
#  MAIN
#  --------------------------------------------------------------------------------------------------------------------


fncEnsureElevatedPrivileges
...