You can use 'cut' to extract the last field of a line if you know how many fields there are, eg:
field=`cut -d: -f8 file`
But if you don't know the maximum number of fields or the number of fields per line are not consistent, awk can come to the rescue. awk has the inbuilt variable NF for the number of fields. By using this variable we can use it to extract the last field by using:
field=`awk -F: '{print $NF}'`
or you can use calculations to retrieve any field relative to the last field. For example to retrieve the second last field, use:
field=`awk -F: '{print $(NF-1)}'`
