Windows的long name 和 short name

An 8.3 filename[1] (also called a short filename or SFN) is a filename convention used by old versions of DOS , versions of Microsoft Windows prior to Windows 95 , and Windows NT 3.51 . It is also used in modern Microsoft operating systems as an alternate filename to the long filename for compatibility with legacy programs. The filename convention is limited by the FAT file system .

How to convert a long filename to a short filename

Sometimes it may be desirable to convert a long filename to a short filename, for example when working with the command prompt. A few simple rules can be followed to attain the correct 8.3 filename.


1. A SFN filename can have at most 8 characters before the dot. If it has more than that, you should write the first 6, then put a tilde ~ as the seventh character and a number (usually 1) as the eight. The number distinguishes it from other files with both the same first six letters and the same extension.

2. Dots are important and must be used even for folder names (if there is a dot in the folder name). If there are multiple dots in the long file/directory name, only the last one is used. The preceding dots should be ignored. If there are more characters than three after the final dot, only the first three are used.

3. Generally:

  • Any spaces in the filenames should be ignored when converting to SFN.
  • Ignore all dots except the last one. Leave out the other dots, just like the spaces.
  • Commas and square brackets are changed to underscores.
  • Case is not important, upper case and lower case characters are treated equally.

To find out for sure the SFN or 8.3 names of the files in a directory

use: "dir /x" shows the short names if there is one, and the long names.

or : "dir /-n" shows only the short names, in the original DIR listing format.