Special Characters In File Folder Names

Special characters are problematic for transferring files and folders between different computer systems.  Thus is a best practice, in web based platforms such as HydroShare, to avoid the use of special characters in file and folder names.  HydroShare uses the following two character sets.

Preferred characters

Characters from the following set are preferred in HydroShare and the system will strive to support all functionality for files and folders made up of these characters

a-z, A-Z, 0-9, ‘_’, ‘-’, ‘.’, and foreign language characters as encoded according to the Unicode standard. Double dot ‘..’ as part of a filename or path is also not preferred.

Banned characters 

Characters from the following character set are prohibited in HydroShare file and folder names 

\ / : * ? " < > | 

Also, files or folders named ‘.’ or ‘..’ are not allowed as these have special meaning in some file systems.


Any action that attempts to create a file name that includes one of the banned characters results in an error and the action not being completed.

Actions that result in creation of a file or folder name comprised of non-preferred characters (i.e. characters not on the preferred list), will be completed where possible, but may result in an error as HydroShare depends on 3rd party software libraries and systems, some of which fail for non preferred characters.

When a file with non-preferred characters is in a resource, the resource landing page shows a warning to users with edit permission, to encourage removal of non-preferred characters. 

Loading of an individual file with non-preferred characters into hydroShare will result in the non-preferred characters being stripped from the file name.  Where integrity of the resource functionality depends on presence of the non-preferred characters, users will need to edit the file names to include the needed non-preferred characters.

Unzipping of zip files that contain non-preferred file or folder names will not alter the names of any of the files unzipped.  This then becomes a workaround to add multiple files with non-preferred characters when this is necessary.

Unzipping of a zip file where a file or folder name includes a banned character results in an error. 

The inclusion of non-preferred characters in file and folder names, as described above, is to accommodate resources where files are set up for use by a model dependent on special characters in the filenames or folder hierarchy that it uses.  However, it is important to note, that while non-preferred characters are accommodated to support these use cases, there may be functionality for these files that fails, and users are strongly encouraged to use file and folder names only from the preferred character list to the maximal extent possible.