open (INPUT, "<", $ARGV[0]) || die "\nError: File Read \"$ARGV[0]\"\nError: $!\n\n"; 

while ( $line = <INPUT> ) {
  if ( $line =~ /^(b|f)/) {
    print $line;
  }
}
close INPUT; 

##</code><code>##

b=23 y=0x11 arg=0x70 def=0x1 val=0x234
checking system

b=71 y=0x35 arg=0x87 def=0x3 val=0x76d
h=reg.k2.io.chk 0x2001

b=54 y=0x23 arg=0x78 def=0x2 val=0x65b
f chk.fin.reg.m_cwr 0x213

b=54 y=0x23 arg=0x78 def=0x2 val=0x65b
checking system

b=40 y=0x90 arg=0x34 def=0x5 val=0x2197
f ref.grf.pin.clk_trg 0x0021

##</code><code>##

b=54 y=0x23 arg=0x78 def=0x2 val=0x65b
f chk.fin.reg.m_cwr 0x213
b=40 y=0x90 arg=0x34 def=0x5 val=0x2197
f ref.grf.pin.clk_trg 0x0021

The b must be from f 
From the b and f I want to get the from b (y, arg and def) 
and f (\w+ - chk.fin.reg.m_cwr /ref.grf.pin.clk_trg )