       1msync 22m?4mfileId24m?

              If 4mfileId24m is not specified, or if it is and this system does not
              support the 4mfsync24m system call, issues  a  4msync24m  system  call  to
              flush  all  pending disk output.  If 4mfileId24m is specified and the
              system does support the 4mfsync24m system call, issues  an  4mfsync24m  on
              the  file corresponding to the specified Tcl 4mfileId24m to force all
              pending output to that file out to the disk.

              If 4mfileId24m is specified, the file must be writable.  A 1mflush 22mwill
              be issued against the 4mfileId24m before the sync.

              The  4minfox24m  4mhave_fsync24m command can be used to determine if "1msync0m
              4mfileId24m" will do a 4msync24m or a 4mfsync24m.
