CODEWITHSUNDEEP
windowsfilebatch-filecmdntfs
unclemeat
unclemeat

Reputation: 5197

Strange stdout redirect behavior

I noticed some strange behavior in redirecting stdout to files with special characters in 'the name'.

The ones I've found:

echo.>f,test produces a file called f, containing the text ,test. Same with ., ; and <space> (obviously the comma changes to whatever character).

echo.>f.:test produces a file of zero bytes called F~000%HK. The first character in the output file name corresponds to the redirect 'file name' between the redirect character and .: capitalized (I believe the . is ignored/removed for the same reason trying to create a file called f.... just creates a file called f). I have no idea what the rest means, as changing the text after the 'file name' changes nothing. i.e. echo.>f.:nope still produces the empty file F~000%HK.

Another example of the same thing; echo.>test.:test produces a file of zero bytes called TEST~4N5.

In Batch the latter example produces the same result of empty files with the strange names, but the former example instead produces a file called f containing an empty line.

Any explanation / 'anomalies' to add?

Upvotes: 2

Views: 95

Answers (1)

npocmaka
npocmaka

Reputation: 57252

, ; = <space> <tab> are standard delimiters so echo.>f,test is the same as echo. ,test>f . You can see what really happens in this case from a batch batch file with turned on echo.(just set echo on before the redirection). The redirection syntax could be tricky as it takes for a file only the first argument and is with higher prio than the commands. You can change the result with echo. >"f,test"

As for the echo.>test.:test - you are redirecting to Alternate data streams (are you with FAT32 or NTFS . FAT32 does not support ADS and results there may produce something different)? with dir /r (r switch is available from vista and above) or streams.exe from sysinternals you can check the state of ADS.To see the ADS content you can use more command:

more<test.:test

Here are the commands that I know that can read ADS: FOR /F , FIND , FINDSTR ,MORE , CERTUTIL ,CLIP ,EXPAND , SORT , MOFCOMP , FTP -S , CSCRIPT , WSCRIPT

Notepad and Wordpad will delete the ADS if they open a file that have one.

Upvotes: 3

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