COMPUTE DATE

        [SIC\]COMPUTE Modification_Date DATE Filename

    Return the last modification date of the file Filename into the  integer
    variable  Modification_Date.  Used  in procedures to check when file has
    last been changed.

    If the output variable is a 4-bytes integer (Fortran I*4), returned val-
    ue  is  in  seconds  since 01-jan-1970. As the value will overflow after
    19-JAN-2038, this syntax is obsolescent and  will  be  removed  at  some
    point.  Consider  using  I*8 output variable (in nanoseconds) or the SIC
    MODIFIED command.

    If the variable is a 8-bytes integer (Fortran I*8), returned value is in
    nanoseconds  since  01-jan-1970.  In  the latter case, your system (e.g.
    Linux >= 2.5.48) AND filesystem (e.g. ext4) must support timestamp gran-
    ularity  below  the second. If not, value precision is limited to 1 sec-
    ond.