windows 7 – How do you use gpg4win from command line to encrypt or decrypt a file?

This doesn’t make much sense to me but I just opened cygwin, which I haven’t tried installing gpg in.. and I found the gpg command worked(though I had to do ctrl-c when running it from cygwin but it worked). I did which gpg and it showed /cygdrive/c/Program Files (x86)/GnuPG/bin/gpg

I then opened a regular cmd prompt

C:Program Files (x86)GnuPGbin>dir gpg*
 Volume in drive C has no label.
 Volume Serial Number is 4645-5DCE

 Directory of C:Program Files (x86)GnuPGbin

03/09/2020  15:39           399,008 gpg-agent.exe
03/09/2020  15:39           171,680 gpg-connect-agent.exe
03/09/2020  15:39            84,128 gpg-preset-passphrase.exe
03/09/2020  15:39           216,736 gpg-wks-client.exe
03/09/2020  15:39         1,088,160 gpg.exe
03/09/2020  15:39           150,176 gpgconf.exe
03/09/2020  15:39            24,224 gpgme-w32spawn.exe
03/09/2020  15:39           496,800 gpgsm.exe
03/09/2020  15:39           158,880 gpgtar.exe
03/09/2020  15:39           514,208 gpgv.exe
              10 File(s)      3,304,000 bytes
               0 Dir(s)  34,930,319,360 bytes free

C:Program Files (x86)GnuPGbin>

gpg.exe has “magically” appeared and the date of the files (which is in the UK form dd/mm/yyyy)

C:UsersUser>date
The current date is: 20/11/2020
Enter the new date: (dd-mm-yy)
C:UsersUser>

The date of the files has shifted from 4th september 2020(see directory listing in my question), to 3rd september 2020.. All within 5 minutes.

So it works , and works well and properly , from cmd.exe and I see gpg.exe listed now. But it wasn’t there before!

C:UsersUserbbb>gpg -c a.txt_pwd_a
File 'a.txt_pwd_a.gpg' exists. Overwrite? (y/N) y

C:UsersUserbbb>gpg a.txt_pwd_a.gpg
gpg: WARNING: no command supplied.  Trying to guess what you mean ...
gpg: AES.CFB encrypted data
gpg: encrypted with 1 passphrase
File 'a.txt_pwd_a' exists. Overwrite? (y/N) y

C:UsersUserbbb>