Shell Programming and Scripting

tr ' ' '\n' < a | while read line
do
echo "$line" | egrep -v "hotmail|yahoo" 2>/dev/null 1>&2
if [ $? -eq 0 ]
then
echo "$line"
fi
done

abc@test.com: abc@hotmail.com,abc@yahoo.com
xyz@test.com: xyz@hotmail.com
qwer@test.com: qwer@gmail.com,qwer@aol.com,qwer@test2.com
ghjk@test.com: ghjk@test2.com
abcd@xyz.com: abcd@hjkl.com,abcd@gmail.com,bcd@mil.com

$ sed 's/\([ ,]\)[^@]\+@\(gmail\|yahoo\|hotmail\)\.com,\?/\1/g' input-file

sed -r 's/([ ,])[^@]+@(gmail|yahoo|hotmail)\.com,?/\1/g' input-file

abc@test.com: abc@yahoo.com
xyz@test.com: 
qwer@test.com: qwer@aol.com,qwer@test2.com
ghjk@test.com: ghjk@test2.com
abcd@xyz.com: abcd@hjkl.com,bcd@mil.com

perl -i.bck -pe's/(?:,\s?)?\w+@(?:(?:hot|g)mail|aol|yahoo)\.com,?//g' /path/*

awk -F":" -v OFS=": " '{print $1, gensub(/[^@]+@(gmail|yahoo|hotmail)\.com,?/, "", "g", $2)}' input-file

awk 'BEGIN{FS="[:,]"}
{
 for(i=1;i<=NF;i++) {
  if( $i !~ /yahoo|gmail|hotmail/) {
    printf $i" " 
  }  
 } 
 print ""
}' file