$ ./perm_tasks.pl
OS: cygwin; Perl: v5.36.0

*** Initial permissions (visual check):
-rw-r--r-- 1 ken None 0 Sep  4 02:07 a
-rw-r--r-- 1 ken None 0 Sep  4 02:07 b
-rw-r--r-- 1 ken None 0 Sep  4 02:07 c
-rw-r--r-- 1 ken None 0 Sep  4 02:16 d

*** Initial permissions (program check):
File: 'a'; Perm:  0644; Check: OK
File: 'b'; Perm:  0644; Check: OK
File: 'c'; Perm:  0644; Check: OK
File: 'd'; Perm:  0644; Check: OK

*** Modified permissions (visual check):
-rw-r--r-- 1 ken None 0 Sep  4 02:07 a
-rwxr-xr-x 1 ken None 0 Sep  4 02:07 b
-r--r----- 1 ken None 0 Sep  4 02:07 c
-rwSr-Sr-T 1 ken None 0 Sep  4 02:16 d

*** Modified permissions (program check):
File: 'a'; Perm:  0644; Check: OK
File: 'b'; Perm:  0755; Check: OK
File: 'c'; Perm:  0440; Check: OK
File: 'd'; Perm: 07644; Check: OK

*** Restored permissions (visual check):
-rw-r--r-- 1 ken None 0 Sep  4 02:07 a
-rw-r--r-- 1 ken None 0 Sep  4 02:07 b
-rw-r--r-- 1 ken None 0 Sep  4 02:07 c
-rw-r--r-- 1 ken None 0 Sep  4 02:16 d

*** Restored permissions (program check):
File: 'a'; Perm:  0644; Check: OK
File: 'b'; Perm:  0644; Check: OK
File: 'c'; Perm:  0644; Check: OK
File: 'd'; Perm:  0644; Check: OK