Shell Programming and Scripting

input: Hello world $string$
Expected output: string

echo "Hello world $string$" | awk '/\$.*\$/ { print "match found" }'
echo "Hello world $string$" | awk '/\\$.*\\$/ { print "match found" }'
echo "Hello world $string$" | awk '/\$\$/ { print "match found" }'
echo "Hello world $string$" | awk '/\\$\\$/ { print "match found" }'
echo "Hello world $string$" | awk '/\044.*\044/ { print "match found" }'

echo "Hello world "$"string"$"" | awk -F" " '{print$3}'

$string$

echo 'Hello world $string$' | awk '/\$.*\$/ { print "match found" }'

# echo 'Hello world $string$'|awk '/\$[a-z]*\$/ { print "match found" }'                         
match found

awk '{for (i=1;i<=NF;i++)  if($i ~ /^\$/ && $i ~ /\$$/)  {print substr($i,2,length($i)-2)} }' inputfile

Hello world $string$
abc
def $kk$ df

string
kk

sed -n 's/.*[$]\([^$]*\)[$].*/\1/p'

echo 'Hello world $string$' | awk -F\$ '{print $2}'
string