migrade user credentials

migrate-credentials.sh

#!/bin/bash
#############################
# Migrate User Credentials
#
# @author Matthew Pietz

Mode=0
BackupPath="/tmp/user-mig.$$"
StorageFile="user-migrate.tar.gz"
StartID=1000

declare -i StartID

function Startup() {
	if [ $(id -u) -ne 0 ]; then
		echo "must be root." >&2
		exit 1
	fi

	mkdir -p "$BackupPath"
}

function Cleanup() {
	rm -rf "$BackupPath"
}

function CreateArchive() {
	awk -v LIMIT=$StartID -F: '($3>=LIMIT) && ($3!=65534)' /etc/passwd > "$BackupPath/passwd.mig"

	awk -v LIMIT=$StartID -F: '($3>=LIMIT) && ($3!=65534)' /etc/group > "$BackupPath/group.mig"

	awk -v LIMIT=$StartID -F: '{print $1}' "$BackupPath/passwd.mig" | egrep -f - /etc/shadow > "$BackupPath/shadow.mig"

	cp /etc/gshadow "$BackupPath/gshadow.mig"

	# use ls so that we don't get `./` in the archive
	ls "$BackupPath" | tar -C "$BackupPath/" -czpf "$(pwd)/$StorageFile" -T -

	if [ $? -ne 0 ]; then
		echo "errors while creating file..."
		rm "$(pwd)/$StorageFile"
		Cleanup
		exit 2
	else
		echo "created file: $StorageFile"
		Cleanup
	fi
}

function ApplyArchive() {
	echo "TODO: Apply archive on new computer" >&2
	exit 1
}

function Usage() {
	sed -e 's/^	//' <<EndUsage
	Usage: ${0##*/} [-i LIMIT] -s [FILE]
	   or: ${0##*/} -a [FILE]
	
	    -i LIMIT              Set the start index for UID and GID
	                              Default: 1000
	    -s                    Store credentials in [FILE]
	    -a                    Read and apply credentials from [FILE]
EndUsage
}

function CheckMode() {
	if [ $Mode -gt 0 ]; then
		echo "Only one of -s or -a can be specified" >&2
		exit 1
	fi
	Mode=$1
}

#################################################

Startup

while getopts ":i:sa" Opt; do case $Opt in
	i)	StartID=$OPTARG;;
	s)	CheckMode 1;;
	a)	CheckMode 2;;
	\?)
		echo "Invalid option -$OPTARG" >&2
		exit 1
		;;
	:)
		echo "Option -$OPTARG requires an argument" >&2
		exit 1
		;;
esac; done
shift $((OPTIND-1))

# Set the storage file to use
if [ "$1" ]; then StorageFile="$1"; fi

case $Mode in
	1) CreateArchive;;
	2) ApplyArchive;;
	*) Usage;;
esac

Cleanup