I was working on an infrastructure project one day where I needed to do some connectivity testing on select switch ports VLAN’d to a network that didn’t offer DHCP addressing to connected devices. I walked my laptop down to the switch stack and went through the process of setting my nic to a static IP along with static DNS entries and a new gateway. So, I decided it would be a lot easier to script it.

This script backs-up the original DHCP sttings; builds the static IP configs, along with DNS entries and gateway settings; re-initializes the interface to use those settings; then allows the user to restore the settings back to DHCP when done. It’s not complicated, it’s just easier than doing it all manually.

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This is an adduser script for a linux machine. I wrote it when I had to migrate a substantial number of users from several windows file servers to a newly-built linux server running samba. This new server, located at corporate headquarters, became the primary company file server, which meant it served files up to a large number of local – as well as remote – users. Many of these users did not need a home directory because their home directories lived elsewhere. But, because they had the need for access to files based on group membership, they needed accounts on the machine along with user-based access to group-managed files. This script made the job of moving them all – and assigning them group membership rights – a lot easier.

#!/bin/sh

   ##############################################
   #                                            #
   #    Adduser script for Linux Servers        #
   #                                            #
   #  Allows for variables to be added for      #
   #  customization: groups, home directories,  #
   #  comments, and more...                     #
   #                                            #
   #                                            #
   #     last modified: 01/18/09 by tburns      #
                      SCRIPT_VERSION="1.2"      #
   #                                            #
   #                                            #
   ##############################################

USERADD=/usr/sbin/useradd

USER_HOME_DEFAULT="0"   # if the home directory is /home enter a 1.
                        # Otherwise, enter "0" and a location below

if [ $USER_HOME_DEFAULT = "0" ]; then
     USER_HOME="/sambaFiles/clientFiles/users"
   else
     USER_HOME="/home"
fi

#Enter user data as prompted:
#First, prompt for userid
echo -e "Enter the userid: \c"
read USER_ID
echo ""

#Second, prompt for user's full name
echo -e "Enter the user's full name to be created: \c"
read USER_FULL_NAME
echo ""

#Third, prompt for primary group
echo -e "Enter the user's primary group name: \c"
read PRIMARY_GROUP
echo ""

#Fourth, find out if they need a home directory or not:
echo -e "Should this user have a home directory on this machine? y/n \c"
read CREATE_HOME_DIR
echo ""

#The following routine is for the fat-fingered:

if [ $CREATE_HOME_DIR = "Y" ] || [ $CREATE_HOME_DIR = "y" ]; then
   echo " Ok... The Home directory will be created here: $USER_HOME "
 elif [ $CREATE_HOME_DIR = "N" ] || [ $CREATE_HOME_DIR = "n" ]; then
   echo " This user will not have a Home directory locally "
 else
   echo "You entered $CREATE_HOME_DIR when prompted for a Y/y or an N/n. Try it again"
   echo ""
   echo -e "Should this user have a home directory on this machine? y/n \c"
     read CREATE_HOME_DIR

#But, if the fat-fingered can't get it right... we offer a bailout option:

    if [ $CREATE_HOME_DIR != "Y" ] || [ $CREATE_HOME_DIR != "y" ] ||[ $CREATE_HOME_DIR != "N" ] || [ $CREATE_HOME_DIR$
       echo ""
       echo "That's enough... check your facts! Here's what you entered:  "
       echo " USERADD = $USERADD "
       echo " USER_ID = $USER_ID "
       echo " USER_FULL_NAME = $USER_FULL_NAME "
       echo " PRIMARY_GROUP = $PRIMARY_GROUP "
       echo " CREATE_HOME_DIR = $CREATE_HOME_DIR "
       echo " Now, go back and try again "
    fi
exit 1
fi
echo ""

# Now, make all that stuff work together
echo "Here's what you've got so far: "
       echo " USERADD = $USERADD "
       echo " USER_ID = $USER_ID "
       echo " USER_FULL_NAME = $USER_FULL_NAME "
       echo " PRIMARY_GROUP = $PRIMARY_GROUP "
       echo " CREATE_HOME_DIR = $CREATE_HOME_DIR "
       echo " USER_HOME = $USER_HOME "

#Assuming we are still moving along... and that we may
#actually get to the end of this thing:
echo -e "Do you want to continue? y/n \c"
read CONTINUE
if [ $CONTINUE = "Y" ] || [ $CONTINUE = "y" ]; then
   if [ $CREATE_HOME_DIR = "Y" ] || [ $CREATE_HOME_DIR = "y" ]; then
        if [ $USER_HOME_DEFAULT = "0" ]; then
           echo " mkdir $USER_HOME/$USER_ID "
#          mkdir $USER_HOME/$USER_ID
           USER_HOME_DIR="$USER_HOME/$USER_ID"
           echo " $USERADD -G $PRIMARY_GROUP -c \"$USER_FULL_NAME\" -d $USER_HOME_DIR $USER_ID"
           `$USERADD -G $PRIMARY_GROUP -c "$USER_FULL_NAME" -d $USER_HOME_DIR $USER_ID`
           echo " chown $USER_ID $USER_HOME_DIR"
           chown $USER_ID:$USER_ID $USER_HOME_DIR
        else
           echo " $USERADD -G $PRIMARY_GROUP -c \"$USER_FULL_NAME\" $USER_ID"
           `$USERADD -G $PRIMARY_GROUP -c "$USER_FULL_NAME" $USER_ID`
        fi
   else
      echo " $USERADD -M -G $PRIMARY_GROUP -c \"$USER_FULL_NAME\" $USER_ID"
      `$USERADD -M -G $PRIMARY_GROUP -c "$USER_FULL_NAME" $USER_ID`
   fi
  else
    echo "Ok... we'll stop here..."
    echo ""
exit 1
fi

exit 0