4.4BSD/usr/share/man/cat2/truncate.0

TRUNCATE(2)                 BSD Programmer's Manual                TRUNCATE(2)

NNAAMMEE
     ttrruunnccaattee, ffttrruunnccaattee - truncate a file to a specified length

SSYYNNOOPPSSIISS
     ##iinncclluuddee <<uunniissttdd..hh>>

     _i_n_t
     ttrruunnccaattee(_c_o_n_s_t _c_h_a_r _*_p_a_t_h, _o_f_f___t _l_e_n_g_t_h);

     _i_n_t
     ffttrruunnccaattee(_i_n_t _f_d, _o_f_f___t _l_e_n_g_t_h);

DDEESSCCRRIIPPTTIIOONN
     TTrruunnccaattee() causes the file named by _p_a_t_h or referenced by _f_d to be trun-
     cated to at most _l_e_n_g_t_h bytes in size.  If the file previously was larger
     than this size, the extra data is lost.  With ffttrruunnccaattee(), the file must
     be open for writing.

RREETTUURRNN VVAALLUUEESS
     A value of 0 is returned if the call succeeds.  If the call fails a -1 is
     returned, and the global variable _e_r_r_n_o specifies the error.

EERRRROORRSS
     TTrruunnccaattee() succeeds unless:

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

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

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

     [ENOENT]   The named file does not exist.

     [EACCES]   Search permission is denied for a component of the path pre-
                fix.

     [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]   _P_a_t_h points outside the process's allocated address space.

     FFttrruunnccaattee() succeeds unless:

     [EBADF]    The _f_d is not a valid descriptor.

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

     [EINVAL]   The _f_d is not open for writing.

SSEEEE AALLSSOO
     open(2)

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

HHIISSTTOORRYY
     The ttrruunnccaattee function call appeared in 4.2BSD.

4.2 Berkeley Distribution        June 4, 1993                                2