Shell Programming and Scripting

 
egrep ^\[6-7\].\[0\|5\].\[1-99\].\[1-99\].\[1-99\]$ filename

egrep '^[67]\.[05]\.[1-9][1-9]*\.[1-9][1-9]*\.[1-9][1-9]*$' myFile

  /usr/bin/egrep
     The /usr/bin/egrep utility accepts full regular  expressions
     as described on the regexp(5) manual page, except for \( and
     \), \( and \), \{ and \}, \< and \>, and \n,  and  with  the
     addition of:

egrep '^[67]\.[05]\.[1-9]\{1,2\}\.[1-9]\{1,2\}\.[1-9]\{1,2\}$' myFile