What is the output format of the hexdump command?

echo -n abcd > my_test_file
hexdump my_test_file
# 0000000 6261 6463                              
# 0000004
hexdump -C my_test_file
# 00000000  61 62 63 64                                       |abcd|
# 00000004

Is the file stored on harddisk like the first output and the "hexdump开发者_如何转开发 -C"-output is reordered for readability?

The second hexdump represents the storage on disk. The first variant exists more for historic reasons (16 bit big-endian architecture on PDP-11).