Possible Problems Exchanging Data Between HP-UX and PCs

ASCII End-of-Line Problems

Whenever you exchange data between Microsoft operating systems, Apple Macintosh operating systems, and HP-UX systems, you might run into problems related to the different ways each of these systems determines the end-of-line (EOL) condition in ASCII text files.

The following table shows which characters each of the operating systems use to determine the end of lines in an ASCII text file:

Many file transfer utilities automatically translate the end-of-line characters for you, but it is possible that you will see one or more of the following problems:

If you see any of the above symptoms, the solution is to edit the offending file using an editor or word processor and change the end-of-line characters in your ASCII file to what your operating system is expecting (see Table 2-10 “Operating System End-of-Line Characters”).

The Endian Difference Problem

Though you are less likely to encounter this problem than the end-of-line character problem, and though many utilities and programs are written to automatically account for differences in the endian types of varying machines, you might encounter files that appear to be corrupt on one architecture yet appear to be fine on another. This will most likely occur when sharing a file system between computers of differing endian architectures (such as when using NFS mounts, or Network Operating Systems such as Novell’
s NetWare).

What is Endian?

The term “endian” refers to the order in which bytes in a computer word are numbered. When certain applications write data to a file, they record the bytes of the word in numerical order. Although nearly all computers view a word of memory as having the most significant bit in the left-most position, and the least significant bit in the right-most position, computer architectures vary on whether they number the bytes of a word from left to right, or from right to left.

Big Endian Architectures

Architectures that number the bytes of a word from left to right (byte 0 represents the left-most eight bits of the word) are called “big endian” architectures. Apple Macintosh computers, and many Hewlett-Packard PA-RISC computers are examples of big endian machines.

	NOTE: Newer PA-RISC computers can be either big endian or little endian machines, however the HP-UX operating system is a big endian operating system.

Figure 2-6 A 32-bit example of “Big Endian” architecture

Little Endian Architectures

Architectures that number the bytes of a word from right to left (byte 0 represents the right-most eight bits of the word) are called “little endian” architectures. The Intel x86 and Pentium based computers are examples of little endian machines.

Figure 2-7 A 32-bit example of “Little Endian” architecture