       ftruncate [-fileid] file newsize
              Truncate a file to have a length of at most newsize
              bytes.

              If the option -fileid is specified, file is an open
              file identifier, otherwise it is a file path.

              This  command  is  not available or not fully func-
              tional if the underlying operating  system  support
              is  not available.  The command infox have_truncate
              will indicate if this command may truncate by  file
              path.   The command infox have_ftruncate will indi-
              cate if this command may truncate by file id.

              The -fileid option  is  not  available  on  Windows
              95/NT.

              This command is provided by Extended Tcl.
