China DOS Union

Recently, I have read a lot of discussions about "abnormal directories" and have gained a lot. I have come up with several questions:

1. For the format paths of 8.3 format and long filenames, which one will the system search preferentially? (For example, there are both C:\Program Files and C:\progra~1 directories in the computer)

2. According to the principle of permutation and combination, the short filename can represent at most 9 filenames/directory names with the same first 8 characters. Then, actually test it. Create 20 directories, namely:

aaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaa (1)
aaaaaaaaaaaaaaaaaaaaa (2)
aaaaaaaaaaaaaaaaaaaaa (3)
.....
aaaaaaaaaaaaaaaaaaaaa (20)

dir /x shows:

AAAAAA~1
AAAAAA~2
AAB2DC~1
AAB2EC~1
AAB2FC~1
AAB20D~1
AAB21D~1
AAB22D~1
AAB23D~1
AAB24D~1
AAB25D~1
AAB26D~1
AAAAAA~3
AAC2D4~1
AAC2E4~1
AAC2F4~1
AAC205~1
AAC215~1
AAC225~1
AAC235~1
AAC245~1
AAC255~1
AAC265~1
AAAAAA~4
AAC2DC~1
AAC2EC~1
AA4064~1
AA406C~1
AA5064~1
AA506C~1
AA6064~1

What is the pattern here?

3. Create a D:\...\ directory, and it will display D:\e2e2~1. How to explain this?

In fact, this is an extremely non-standard short filename generation method under NT CMD, and it can even be regarded as a bug. However, there is no such problem under pure DOS and Win9x.

Regarding E2E2~1, it should actually be interpreted as 2E 2E, which are the hexadecimal codes of the two characters "..". And because it is different from its corresponding long filename, the number suffix ~1 is added.

This situation can also occur when the file name contains spaces and is particularly short.