Shell Programming and Scripting

awk -F\| 'BEGIN{split("JAN FEB MAR APR MAI JUN JUL AUG SEP OCT NOV DEC",A," "); while (++i in A)M[A[i]]=i; D[3]; D[6]}
         {for(i in D)$i=sprintf("%02d\\%s\\%s",M[substr($i,3,3)],substr($i,1,2),substr($i,6))}1' OFS=\|

## justdoit ##
ls -1 desiredfiles | 
while read -r infile ; do
 # backup
 cp $infile $infile_bck
 # process
 x="JAN=01 FEB=02 MAR=03 APR=04 MAY=05 JUN=06 JUL=07 AUG=08 SEP=09 OCT=10 NOV=11 DEC=12"
 for i in $(echo "$x" | sed 's/=[0-9]*//g') ; do
  y=$(sed "s/.*\($i\).*/\1/" $infile); y1=$(echo "$x"| sed "s/.*$i=\([0-9]*\).*/\1/")
  sed -i "s/\(.*\)|\(.*\)$y\(.*\)|\(.*\)/\1|$y1\\\\\2\\\\\3\4|/g" $infile 2>/dev/null
 done ;  more $infile
done