Querying filesystem limits

Updated: April 19, 2023

You can query the path-specific configuration limits to determine some of the properties and limits of a specific filesystem.

The full list of these limits is given in the reference for the pathconf() QNX Neutrino library function. The supported configurable filesystem limits include at least the following:

_PC_LINK_MAX
Maximum value of a file's link count.
_PC_MAX_CANON
Maximum number of bytes in a terminal's canonical input buffer (edit buffer).
_PC_MAX_INPUT
Maximum number of bytes in a terminal's raw input buffer.
_PC_NAME_MAX
Maximum number of bytes in a filename (not including the terminating null).
_PC_PATH_MAX
Maximum number of bytes in a pathname (not including the terminating null).
_PC_PIPE_BUF
Maximum number of bytes that can be written atomically when writing to a pipe.
_PC_CHOWN_RESTRICTED
If defined (not -1), indicates that the use of the chown() function is restricted to a process with appropriate privileges, and to changing the group ID of a file to the effective group ID of the process or to one of its supplementary group IDs.
_PC_NO_TRUNC
If defined (not -1), indicates that the use of pathname components longer than the value given by _PC_NAME_MAX will generate an error.
_PC_VDISABLE
If defined (not -1), this is the character value that can be used to individually disable special control characters in the termios control structure.

For more information, see Configurable limits,” above.