file-exists? checks if its argument string names
a file. delete-file deletes its argument file.
These procedures are not part of the Scheme standard,
but are available in most implementations. These
procedures work reliably only for files that are not
directories. (Their behavior on directories is
dialect-specific.)
file-or-directory-modify-seconds returns the time when its
argument file or directory was last modified. Time is
reckoned in seconds from 12 AM GMT, 1 January 1970.
Eg,
The system procedure executes its argument string
as an operating-system command.4 It returns true if the
command executed successfully with an exit status 0,
and false if it failed to execute or exited with a
non-zero status. Any output generated by the command
goes to standard output.
(system"ls")
;lists current directory
(definefname"spot")
(system (string-append"test -f "fname))
;tests if file `spot' exists
(system (string-append"rm -f "fname))
;removes `spot'