Shell Programming and Scripting

awk '{for(i=1;i++<=NF;)if($i~/^apple|^orange/) print $i}' file

tr ' ' '\n' < file | grep -E "^apple|^orange"

tr ' ' '\n' < file |egrep "^apple|^orange"

# time awk '{for(i=1;i<=NF;i++)if($i~/^apple|^orange/) print $i}' file > newfile1

real    0m0.715s
user    0m0.550s
sys     0m0.128s
# time tr ' ' '\n' < file | grep -E "^apple|^orange" > newfile2

real    0m0.864s
user    0m0.550s
sys     0m0.238s
# diff newfile1 newfile2
#

grep -oE '\b(apple|orange)\S*'

perl -nle'print join"\n",/\b((?:apple|orange)\S*)/g'

undef $/;
open FH,"<filename";
$str=<FH>;
$str=~s/\n/ /g;
close FH;
print "$_\n" foreach(grep {m/apple|orange/;} (split(" ",$str)));