Shell Programming and Scripting

 # Make backups of the files
cp /etc/passwd backuppasswd
cp /etc/group backupgroup
# Variables for the 2 input files
inputpasswd=input
inputgroup=input2
awk -F: '{print $1}' $inputgroup > groupnames
awk -F: '{print $3}' $inputgroup > groupids
groupnum=1
# Add and update groups
while read groupline; do
    echo "$groupline"
    othergroupid=`sed -n "$groupnum{p;g;}" groupids`
    groupid=`awk -F: '$1=="'"$groupline"'" {print $3}' /etc/group`
    if [ "$groupid" == "" ]; then
        echo "Need to Add Group"
        groupadd -g $otherid $groupline
    fi
    ((groupnum++));
    if [ "$groupid" != "$othergroupid" ]; then
        echo "Group ID Mismatch"
        groupmod -g $othergroupid $groupline
    fi
#    echo Changing Group File and Directory Ownership
#    find / -group $groupid | xargs chgrp $othergroupid
done < groupnames
awk -F: '{print $1}' $inputpasswd > usernames
awk -F: '{print $3}' $inputpasswd > ids
awk -F: '{print $4}' $inputpasswd > groups
awk -F: '{print $5}' $inputpasswd > descriptions
usernum=1
#Add and update users
while read userline; do
    echo "$userline"
    otherid=`sed -n "$usernum{p;g;}" ids`
    othergroup=`sed -n "$usernum{p;g;}" groups`
    id=`awk -F: '$1=="'"$userline"'" {print $3}' /etc/passwd`
    group=`awk -F: '$1=="'"$userline"'" {print $4}' /etc/passwd`
    description=`sed -n "$usernum{p;g;}" descriptions`

    echo "$description"
    if [ "$id" == "" ]; then
        echo "Need to Add User"
        useradd -g $othergroup -c $description -u $otherid $userline
    fi
    ((usernum++));

    if [ "$id" != "$otherid" ]; then
        echo "ID Mismatch"
        usermod -u $otherid $userline
    fi
#    echo "Changing User File and Directory Ownership"
#    find / -user $id | xargs chown $otherid
#    echo "Changing Group File and Directory Ownership"
#    find / -user $id | xargs chgrp $othergroup
    if [ "$group" != "$othergroup" ]; then
        echo "Change User Primary Group"
        usermod -g $othergroup $userline
    fi
    echo
done < usernames
grouplist=`awk -F: '{print $1}' $inputgroup`
#Add users to their appropriate groups
for x in ${grouplist}; do
    #Use awk to get the actual comma separated list of users for each group
    userlist=`awk -F: '$1=="'"${x}"'" {print $4}' $inputgroup`
    arrayuserlist=`echo $userlist | tr ',' ' '`
    for y in ${arrayuserlist}; do
        echo "Adding to Group"
        echo "${x} ${y}"
        usermod -a -G ${x} ${y}
    done
done
#that section needs some rework so it gets the groups from imported file
rm ./groupnames
rm ./groupids
rm ./usernames
rm ./ids
rm ./groups
rm ./descriptions

myvar="$(echo "abcde" | tr '[a-z]' '[A-Z]')"
echo $myvar      # would yield "ABCDE"

if [ $(command $myvars ; echo $?) -gt 0 ] ; then
     echo "ERROR: command had a nonzero return code"
else
     echo "Everything ok, command has returned 0
fi

IFS=':'
cat /etc/passwd | while read Name junk UID PGrp Gecos junk ; do
     echo "------------------------"
     echo "User.........: $Name"
     echo "UID..........: $UID"
     echo "primary group: $PGrp"
     echo "Gecos........: $Gecos"
done