Suppose i have 2 config files such as:file 1:smtpd_sasl_auth_enable = yesbroken_sasl_auth_clients = yessmtpd_sasl_authenticated_header = yesvirtual_gid_maps = static:5000File 2:virtual_gid_maps = static:5000broken_sasl_auth_clients = yessmtpd_sasl_authenticated_header = yesif you see carefully, you'll see together have a line begin with virtua_gid_* but file 1 have it in end of file but file 2 have it head of file.Suppose i have 2 files with same lines with difference positions , but positions not important for me, to be or not to be is important.HOW CAN I COMPARE MY FILES? 
how to compare total file
scripting;diff
If the positions are not important, you can sort the files and then, perform a diff.  You will have to save the sorted files in temporary area.sort file1 > /tmp/file1sort file2 > /tmp/file2diff /tmp/file1 /tmp/file2You may also want to try vimdiff instead of diff.