NAME

       truncate, ftruncate — truncate or extend a file to a specified length

LIBRARY

       Standard C Library (libc, -lc)

SYNOPSIS

       #include <unistd.h>

       int
       truncate(const char *path, off_t length);

       int
       ftruncate(int fd, off_t length);

DESCRIPTION

       The  truncate() system call causes the file named by path or referenced by fd to be truncated or extended
       to length bytes in size.  If the file was larger than this size, the extra data is lost.  If the file was
       smaller than this size, it will  be  extended  as  if  by  writing  bytes  with  the  value  zero.   With
       ftruncate(), the file must be open for writing.

RETURN VALUES

       Upon  successful  completion,  the value 0 is returned; otherwise the value -1 is returned and the global
       variable errno is set to indicate the error.  If the file to be modified is not a directory or a  regular
       file, the truncate() call has no effect and returns the value 0.

ERRORS

       The truncate() system call succeeds unless:

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

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

       [ENOENT]           The named file does not exist.

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

       [EACCES]           The named file is not writable by the user.

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

       [EPERM]            The named file has its immutable or append-only flag set, see  the  chflags(2)  manual
                          page for more information.

       [EISDIR]           The named file is a directory.

       [EROFS]            The named file resides on a read-only file system.

       [ETXTBSY]          The file is a pure procedure (shared text) file that is being executed.

       [EFBIG]            The length argument was greater than the maximum file size.

       [EINVAL]           The length argument was less than 0.

       [EIO]              An I/O error occurred updating the inode.

       [EFAULT]           The path argument points outside the process's allocated address space.

       The ftruncate() system call succeeds unless:

       [EBADF]            The fd argument is not a valid descriptor.

       [EINVAL]           The fd argument references a socket, not a file.

       [EINVAL]           The fd descriptor is not open for writing.

SEE ALSO

       chflags(2), open(2)

HISTORY

       The truncate() system call appeared in 4.2BSD.

BUGS

       These calls should be generalized to allow ranges of bytes in a file to be discarded.

       Use of truncate() to extend a file is not portable.

Debian                                          December 13, 2006                                    TRUNCATE(2)