Migrate Linux UIDs and GIDS to new box excluded system IDs

migration.sh

#!/bin/bash
#This shell script is moving uids and gids to new server without grabbing the system accounts
#The one caveat with this script is confirming the UID start limit and upper limit for your distro
#This can be confirmed by checking the /etc/libuser.conf it is denoted there in RHEL distros
#This script is to be ran from the /tmp directory as denoted in BASE
#This script is valid for 6.5 RHEL and down as is. Change UGIDLIMIT to 1000 for v7.0
#Create directory for migration files
BASE=/tmp
 
if [ -d ${BASE}/move ]
then
echo “The move directory exists.”
else
echo “Creating the move directory.”
mkdir ${BASE}/move
fi
 
#Setup UID filter limit to setup UID start limit for normal user account.
#RHEL/CentOS/Fedora Core : Default is 500 and upper limit is 65534 /etc/libuser.conf
#This should filter out the system accounts
 
export UGIDLIMIT=500
 
#Now copy /etc/passwd accounts to /tmp/move/passwd.mig using awk to filter out system account i.e. only copy user accounts
awk -v LIMIT=$UGIDLIMIT -F: '($3>=LIMIT) && ($3!=65534)' ${BASE}/passwd > ${BASE}/move/passwd.mig
 
#Copy /etc/group file
awk -v LIMIT=$UGIDLIMIT -F: '($3>=LIMIT) && ($3!=65534)' ${BASE}/group > ${BASE}/move/group.mig
 
#Copy Shadow File
awk -v LIMIT=$UGIDLIMIT -F: '($3>=LIMIT) && ($3!=65534) {print $1}' ${BASE}/passwd | tee - |egrep -f - ${BASE}/shadow > ${BASE}/move/shadow.mig
 
#Append the files in etc from the filtering above on new server
#cat ${BASE}/move/passwd.mig >> /etc/passwd
#cat ${BASE}/move/group.mig >> /etc/group
#cat ${BASE}/move/shadow.mig >> /etc/shadow