Neither are actually files. They are references to directories, the current one and the parent directory, respectively. They can be used in file copy and move operations in place of explicitly printing the directory names. For instance:
mv ./* ..
would move all files from the child directory into it's parent.
No difference, really. Unix is an OS (Operating System)
what are similarities and differences between linux and unix?
Unix is an operating system, Java is a language.
The Unix file contains which kinds of fields?
Since there isn't a UNIX 95 or UNIX 98 per se, I think you are referring to Windows 95 or Windows 98..
Unix is the name of an Operating System (software) and Cisco is the name of a technology company.
unix is a multiuser operating system but widows is a single user operating system.
Unix is a specification. Mac OS X is a certified implementation of Unix. This like asking "What is the difference between a turtle and a red-eared slider."
There is no the system file. There are many files necessary to create a working Unix system.
Unix is a multi user, multi processing and multi tasking operating system
The most common between Unix systems would be NFS Network File System.
The host file in Unix is usually located in the /etc directory.