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FORTRAN-80
6.2.2.2
File Disposition Specifier
The
format
of
the file disposition specifier
is
STATUS =
stat
where
'stat'
is
a character expression evaluating
to
'KEEP'
or
'DELETE'.
If
this
specifier
is
omitted, the default value
is
'DELETE'
for a file
that
previously
had
a
status
of
'SCRATCH',
and
'KEEP'
otherwise. Under no circumstances can
'KEEP'
be specified for a file opened with
'SCRATCH'
status.
If
'KEEP'
is
specified for
an
existing file, the file continues to exist
after
the
CLOSE
statement
is
executed. Otherwise,
'KEEP'
has no effect.
If
'DELETE'
is
specified, the file ceases to exist
after
the
CLOSE
statement
is
ex-
ecuted.
Following
normal
program
termination, all connected units are closed. Scratch units
are deleted; all others
are
closed with disposition
'KEEP'.
Example:
CLOSE
(3,
ERR = 1020, STATUS
='
KEEP')
6.2.3 BACKSPACE Statement
The
BACKSPACE
statement causes the file connected to the specified unit to be
positioned before the preceding record. Its possible formats are
BACKSPACE
unit
BACKSPACE (arg-list)
where
'unit'
is
an external unit specifier
and
'arg-list'
is
a list
of
arguments separated
by commas. The list
of
arguments is:
[UNIT
=]
unit
IOSTAT =
stname
ERR =
stl
External unit specifier
110
status specifier
Error
specifier
The argument list must include an external unit specifier (section 6.2.1.1)
and
may
contain
an
110
status specifier (section 6.2.1.2)
and
an
error
specifier (section
6.2.1.3). The file being backspaced must be connected for sequential access.
If
the file has no preceding record, the
BACKSPACE
statement has no effect.
If
the
end-of-file condition has occurred, the file
is
positioned such
that
the last record
of
the file becomes the preceding record.
Backspacing over a record written using list-directed formatting
is
not
allowed.
Backspacing a nonexistent file
or
unit
is
prohibited also.
Examples:
BACKSPACE 3
BACKSPACE
(3,
ERR = 1020)
6.2.4 REWI N D Statement
The
REWIND
statement causes the file connected
to
the specified unit
to
be reposi-
tioned
at
its initial point. The file must be connected for sequential access. The
possible formats for the
REWIND
statement are
REWIND
unit
REWI N D(arg-list)
Input/Output
6-9