Filename rules

QNX SDP8.0User's GuideUser

QNX OS 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.

The maximum length of a filename depends on the type of filesystem. Individual bytes within the filename may have any value except the following (all values are in hexadecimal):

  • 0x00 through 0x1F (all control characters)
  • 0x2F (/)
  • 0x7F (rubout)
  • 0xFF

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 Power-Safe filesystem (fs-qnx6.so), 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 OS can translate these filenames to UTF-8 representations, but you must tell the filesystem which codepage to use via a command-line option. For more information see fs-dos.so in the Utilities Reference.

Note:
All our disk filesystems— fs-dos.so, fs-ext2.so, the Power-safe filesystem (fs-qnx6.so), and fs-udf.so—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.
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