Filename rules

QNX Neutrino supports a variety of filesystems, each of which has different capabilities and rules for valid filenames.

For information about filesystem capabilities, see the Working with Filesystems chapter; for filesystem limits, see the Understanding System Limits chapter.

In the QNX 4 filesystem, filenames can be up to 48 bytes long, but you can extend them to 505 bytes (see "Filenames" in Working with Filesystems). Individual bytes within the filename may have any value except the following (all values are in hexadecimal):

If you're using UTF-8 representations of Unicode characters to represent international characters, the limit on the filename length will be lower, depending on your use of characters in the extended range.

In the QNX 4 filesystem, you can use international characters in filenames by using the UTF-8 encoding of Unicode characters. Filenames containing UTF-8 characters are generally illegible when viewed from the command line.

You can also use the ISO-Latin1 supplemental and PC character sets for international characters; however, the appearance of these 8-bit characters depends on the display settings of your terminal, and might not appear as you expect in other operating systems that access the files via a network.

Most other operating systems, including Microsoft Windows, support UTF-8/Unicode characters. Filenames from older versions of Microsoft Windows may be encoded using 8-bit characters with various language codepage in effect. The DOS filesystem in QNX Neutrino can translate these filenames to UTF-8 representations, but you need to tell the filesystem which codepage to use via a command-line option. For more information see in the Utilities Reference.

Note: All our disk filesystems except—i.e.,,,, the Power-safe filesystem (, and—use UTF-8 encoding for presentation of their filenames; attempts to specify a filename not using UTF-8 encoding will fail (with an error of EILSEQ) on these filesystems.