August 14, 2008 PATHCONF 2

### NAME

pathconf, fpathconf - get configurable pathname variables

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```long` pathconf(```const char *path``, int name`)
```long` fpathconf(```int fd``, int name`)

### DESCRIPTION

The pathconf(``) and fpathconf(``) functions provide a method for applications 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:

```_PC_LINK_MAX`
  The maximum file link count.

```_PC_MAX_CANON`
  The maximum number of bytes in terminal canonical input line.

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

```_PC_NAME_MAX`
  The maximum number of bytes in a filename, not including a terminating null character.

```_PC_PATH_MAX`
  The maximum number of bytes in a pathname, including the terminating null character.

```_PC_PIPE_BUF`
  The maximum number of bytes which will be written atomically to a pipe.

```_PC_CHOWN_RESTRICTED`
  Return 1 if appropriate privileges are required for the chown(2) system call, otherwise 0.

```_PC_NO_TRUNC`
  Return 1 if filenames longer than ```{NAME_MAX}` are truncated.

```_PC_VDISABLE`
  Returns the terminal character disabling value.

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

```_PC_FILESIZEBITS`
  If the maximum size file that could ever exist on the mounted file system is ```maxsize`, then the returned value is 2 plus the floor of the base 2 logarithm of ```maxsize`.

```_PC_SYMLINK_MAX`
  The maximum number of bytes in a symbolic link.

```_PC_2_SYMLINKS`
  When referring to a directory the system supports the creation of symbolic links within that directory; for nondirectory files, the meaning of ```{_PC_2_SYMLINKS}` is undefined.

### RETURN VALUES

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.

### ERRORS

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, or the implementation does not support an association of the variable name with the associated file.

pathconf(``) will fail if:

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

[```EIO`]
  An I/O error occurred while reading from or writing to the file system.

[```ELOOP`]
  Too many symbolic links were encountered in translating the pathname.

[```ENAMETOOLONG`]
  A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.

[```ENOENT`]
  The named file does not exist.

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

fpathconf(``) will fail if:

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

[```EIO`]
  An I/O error occurred while reading from or writing to the file system.

### SEE ALSO

sysctl(3)

### STANDARDS

The pathconf(``) and fpathconf(``) functions conform to ISO/IEC 9945-1:1990 (``POSIX.1'') .

### HISTORY

The pathconf and fpathconf functions first appeared in 4.4BSD.