Shell Programming and Scripting

echo "sstring garbage adfsdf tab.col1 lkad rjfj tab2.col2 adja tab2.col4 garbage" |grep -o "[[:graph:]]*\.[[:graph:]]*"

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$ echo "sstring garbage adfsdf tab.col1 lkad rjfj tab2.col2 adja tab2.col4 garbage" | perl -ne '
  while(/[^.]* ([^. ]+)\.([^. ]+)/g){print "$1.$2 "} END {print "\n"}'
tab.col1 tab2.col2 tab2.col4 
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$ 

for i in $str; do case $i in *?.?*) echo $i; esac; done

pat="[^ \t]\{1,\}\.[^ \t]\{1,\}"
echo $str | sed "s|$pat|&\n|g" | sed -n "s|.*[ \t]\($pat\).*|\1|p"

echo $str | awk '/\./' RS=" "