I am trying to Build a Incremental Backup Script using Percona Innobackupex , what my problem is i need a shell script to segregate the both First LSN and Last LSN from the Log Output of Full Backup, lets say my Output from the log File is

cat /data/test_backup/test.log | grep "Transaction log of lsn"

xtrabackup: Transaction log of lsn (38491856810) to (38491856819) was copied.

i want to segregate the data in the braces as

FirstLSN = 38491856810
LastLSN = 38491856819

into an output file and use the Last LSN to take incremental Backup or append the LSN Detail directly to my Full backup Script running Log