adding date to a filename

 Spliting filename & extension :-

Option, 1
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[rajesh@rhel6 ~]$ FILE=somefile.txt
[rajesh@rhel6 ~]$ echo $FILE
somefile.txt
[rajesh@rhel6 ~]$ NAME=${FILE%.*}
[rajesh@rhel6 ~]$ echo $NAME
somefile
[rajesh@rhel6 ~]$ EXT=${FILE#*.}
[rajesh@rhel6 ~]$ echo $EXT
txt
[rajesh@rhel6 ~]$ DATE=`date +%d-%m-%y`
[rajesh@rhel6 ~]$ echo $DATE
18-06-13
[rajesh@rhel6 ~]$ NEWFILE=${NAME}_${DATE}.${EXT}
[rajesh@rhel6 ~]$ echo $NEWFILE
somefile_18-06-13.txt
[rajesh@rhel6 ~]$

Option,2 :However, this won't work with multiple "." in the file name.
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[rajesh@rhel6 ~]$ echo $FILE
somefile.txt
[rajesh@rhel6 ~]$
[rajesh@rhel6 ~]$ NAME=`echo $FILE | cut -d. -f1 `
[rajesh@rhel6 ~]$ echo $NAME
somefile
[rajesh@rhel6 ~]$ EXT=`echo $FILE | cut -d. -f2`
[rajesh@rhel6 ~]$ echo $EXT
txt