truncate(2)                                           truncate(2)



NAME
     truncate, ftruncate - truncate a file to a specified length

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

     int ftruncate(fd, length)
     int fd, 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.

STATUS MESSAGES AND VALUES
     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.

     The truncate program will fail if:

     EPERM
          The pathname contains a character with the high-order
          bit set.

     ENOENT
          The pathname was too long.

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

     EPERM
          A pathname contains a character with the high-order bit
          set.

     ENAMETOOLONG
          A component of a pathname exceeded NAME_MAX characters,
          or an entire pathname exceeded PATH_MAX.

     ELOOP
          Too many symbolic links were encountered in translating
          a pathname.

     ENOENT
          The named file does not exist.

     EACCES
          A component of the path prefix denies search



January 1992                                                    1

truncate(2)                                           truncate(2)



          permission.

     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.

             Note:  If you are running an NFS system and you
             are accessing a shared binary remotely, it is
             possible that you will not get this errno.


     EFAULT
          name points outside the process's allocated address
          space.

     ftruncate will fail if:

     EBADF
          The fd is not a valid descriptor.

     EINVAL
          The fd references a socket, not a file.

LIMITATIONS
     Partial blocks discarded as the result of truncation are not
     zero filled; this can cause holes in files which do not read
     as zero.

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

SEE ALSO
     open(2)
















2                                                    January 1992