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PATHCONF(2)                 BSD System Calls Manual                PATHCONF(2)

     pathconf, fpathconf -- get configurable pathname variables

     #include <&lt;unistd.h>&gt;

     pathconf(const char *path, int name);

     fpathconf(int fd, int name);

     The pathconf() and fpathconf() functions provide a method for applica-
     tions to determine the current value of a configurable system limit or
     option variable associated with a pathname or file descriptor.

     For pathconf, the path argument is the name of a file or directory.  For
     fpathconf, the fd argument is an open file descriptor.  The name argument
     specifies the system variable to be queried.  Symbolic constants for each
     name value are found in the include file <unistd.h>.

     The available values are as follows:

             The maximum file link count.

             The maximum number of bytes in a terminal canonical input line.

             The maximum number of bytes for which space is available in a
             terminal input queue.

             The maximum number of bytes in a file name.

             The maximum number of bytes in a pathname.

             The maximum number of bytes which will be written atomically to a

             Returns 1 if appropriate privileges are required for the chown(2)
             system call, otherwise 0.  IEEE Std 1003.1-2001 (``POSIX.1'')
             requires appropriate privilege in all cases, but this behavior
             was optional in prior editions of the standard.

             Returns 1 if attempts to use pathname components longer than
             {NAME_MAX} will result in an [ENAMETOOLONG] error; otherwise,
             such components will be truncated to {NAME_MAX}.  IEEE Std
             1003.1-2001 (``POSIX.1'') requires the error in all cases, but
             this behavior was optional in prior editions of the standard, and
             some non-POSIX-compliant file systems do not support this behav-

             Returns the terminal character disabling value.

             Returns 1 if the filesystem supports the creation of symbolic
             links within the specified directory; the meaning of
             _PC_2_SYMLINKS is unspecified for non-directory files.

             Minimum number of bytes of storage allocated for any portion of a

             Returns 1 if asynchronous I/O is supported, otherwise 0.

             Number of bits needed to represent the maximum file size.

             Returns 1 if prioritized I/O is supported, otherwise 0.

             Recommended increment for file transfer sizes between

             Maximum recommended file transfer size.

             Minimum recommended file transfer size.

             Recommended file transfer buffer alignment.

             Maximum number of bytes in a symbolic link.

             Returns 1 if synchronized I/O is supported, otherwise 0.

             The resolution in nanoseconds of file timestamps.

     If the call to pathconf or fpathconf is not successful, -1 is returned
     and errno is set appropriately.  Otherwise, if the variable is associated
     with functionality that does not have a limit in the system, -1 is
     returned and errno is not modified.  Otherwise, the current variable
     value is returned.

     If any of the following conditions occur, the pathconf and fpathconf
     functions shall return -1 and set errno to the corresponding value.

     [EINVAL]           The value of the name argument is invalid.

     [EINVAL]           The implementation does not support an association of
                        the variable name with the associated file.

     [EIO]              An I/O error occurred while reading from the file sys-

     pathconf() will fail if:

     [ENOTDIR]          A component of the path prefix is not a directory.

     [ENAMETOOLONG]     A component of a pathname exceeded NAME_MAX characters
                        (but see _PC_NO_TRUNC above), or an entire pathname
                        (including the terminating NUL) exceeded PATH_MAX

     [ENOENT]           The named file does not exist.

     [EACCES]           Search permission is denied for a component of the
                        path prefix.

     [ELOOP]            Too many symbolic links were encountered in translat-
                        ing the pathname.

     [EFAULT]           path points outside the process's allocated address

     fpathconf() will fail if:

     [EBADF]            fd is not a valid open file descriptor.

     sysconf(3), sysctl(3)

     The pathconf and fpathconf functions conform to IEEE Std 1003.1-2008

     The pathconf and fpathconf functions first appeared in 4.4BSD.

BSD                             March 28, 2017                             BSD