Shell Programming and Scripting

1_HELLO_HOW_ARE_YOU_BYE_TEST
1_HELLO_WHERE_ARE_BYE_TEST
1_HELLO_HOW_BYE_TEST

HOW_ARE_YOU
WHERE_ARE
HOW

awk -F"HELLO_" '{print $2}' filename | awk -F"_BYE" '{print $1}'

$var1 = `awk -F"HELLO_" '{print $2}' filename | awk -F"_BYE" '{print $1}'`

Use of uninitialized value $2 in concatenation (.) or string.
Use of uninitialized value $1 in concatenation (.) or string.

 
sed 's/1_HELLO_\(.*\)_BYE\(.*\)/\1/g' filename

 
bash-3.00$ sed 's/1_HELLO_\(.*\)_BYE\(.*\)/\1/g' a
HOW_ARE_YOU
WHERE_ARE
HOW

$ perl -pe 's/.+HELLO_(.+)_BYE.+/\1/' file
HOW_ARE_YOU
WHERE_ARE
HOW

open(FILE, "<file") || die;
my $var;
while(<FILE>) {
      $_ =~ m/.+HELLO_(.+)_BYE.+/g;  
      $var = $1;
      print $var;
}