Shell Programming and Scripting

ID|name|contact_date
101|Kay|2013-12-26
102|let|2013-12-26

while IFS="|" read a c b
do
[[ p=$(date -d "$b" +"%m/%d/%Y %r") ]] && print $a"|"$c"|"$p || print $a"|"$c"|"$b
done<file

sed -r 's/(([^\|]*\|){2})([0-9]{4}(-[0-9]{2}){2})/date -d "\3" +"\1%m\/%d\/%Y %r"/e' file

$ cat file
ID|name|contact_date
101|Kay|2013-12-26
102|let|2013-12-26

awk '

function cmd(cmde,result){ 
                              while ((cmde | getline line) > 0)
                                  {
                                      result = result (result=="" ? "" : "\n")line
                                  }
                              close(cmde)
                              return result
                         }

                     NR>1{
                          $3 = cmd("date" " " "-d""\""$3"\"" " " "+%m/%d/%Y\\ %r")
                         }1
    ' FS="|" OFS="|"  file

ID|name|contact_date
101|Kay|12/26/2013 12:00:00 AM IST
102|let|12/26/2013 12:00:00 AM IST

awk 'NR==1 {print;next} {split ($3, T, "-"); $3=sprintf("%s/%s/%s 00:00:00:00", T[2], T[3], T[1])}1' FS="|" OFS="|" file
ID|name|contact_date
101|Kay|12/26/2013 00:00:00:00
102|let|12/26/2013 00:00:00:00

awk -F\| 'NR>1{split($3,T,"-");$3=T[2]"/"T[3]"/"T[1]" 00:00:00"}1' OFS=\| infile