TRUNCATE(2)                          BSD                           TRUNCATE(2)



NAME
     truncate - truncate a file to a specified length

SYNOPSIS
     truncate(path, length)
     char *path;
     off_t length;

     ftruncate(fd, length)
     int fd;
     off_t length;

DESCRIPTION
     truncate causes the file named by path or referenced by fd to be
     truncated to at most length bytes in size.  If the file previously was
     larger than this size, the extra data is lost.  With ftruncate, the file
     must be open for writing.

ERRORS
     truncate succeeds unless any of the following are true:

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

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

     [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.

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

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

     ftruncate succeeds unless any of the following are true:

     [EBADF]          The fd is not a valid descriptor.

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

     [EINVAL]         The fd is not open for writing.

SEE ALSO
     open(2)

DIAGNOSTICS
     A value of 0 is returned if the call succeeds.  If the call fails a -1 is

     returned, and the global variable errno specifies the error.

NOTES
     Under other implementations, truncate fails if the following is true:

     [EINVAL]         The pathname contains a character with the high-order
                      bit set.

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