Windows 10: Case sensitive file and folder names
By default, Windows processes treat the file system as case insensitive. They do not differentiate between files or folders based on case. For example, they view FILE.txt and file.txt as the same file. Even where their content and all other information is different.
In normal operation this does not cause an issue. However, problems may occur where files or folders came from a file system that supports case sensitivity. For example, Linux or UNIX. Or where the computer is using the Windows Subsystem for Linux. A compatibility layer for natively running Linux binary executables on Windows.
To make it easier to deal with case sensitivity when handling this type of file or folder. The Windows 10 April 2018 Update (version 1803) introduced a new flag, configurable on a per-directory basis. When enabled, all Windows processes will respect the case sensitivity of the folder and its files. So they view FILE.txt and file.txt as different files. This setting only applies to the selected folders and associated files. Not the entire file system. Additionally, the settings is not inherited by any sub-folders created in a case sensitive directory.
This can affect user entered file and folder location in some native Windows processes, including Managed Antivirus Exclusions. If the location does not precisely match the case file and folder case. The Windows process will be unable to query these locations.
Managed Antivirus Exclusion Example
The following example uses the eicar anti-malware test file.
Case Sensitive File Location
Managed Antivirus Exclusion
Test file ignored (excluded)
Test file quarantined
Check Folder Case Sensitivity
To check whether a folder is case sensitive, run the following from a command prompt:
fsutil.exe file queryCaseSensitiveInfo <path>
C:\ >fsutil.exe file queryCaseSensitiveInfo C:\case_sensitivity
Case sensitive attribute on directory C:\case_sensitivity is disabled.
What do you want to do?
- Read about Exclusion management and notes
- Review the Exceptions Common System Variables
- Investigate the Microsoft Developer Blog on Per-directory case sensitivity and WSL
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