Newbie can't get --passphrase option to work

[Ryk McDorman]

I was tasked with automating the decryption (and more) of files, so I've written a PowerShell program that does everything I need it to do, except that I can't get the decryption to decrypt without prompting for our passphrase. I'm using a default installation of GnuPG 2.1.19 on Windows 7 (it may go on a Win Server 2012 box for production). 

In the program I'm passing the output and input filenames as parameters to a one-line batch file consisting of this command:
echo <mypassphrase>| "C:\Program Files (x86)\gnuPG\bin\gpg.exe" --batch  --output %1  --passphrase-fd 0 --decrypt %2

I've also tried the -passphrase-file and -passphrase <mypassphrase> options with the same results: when the program runs I'm prompted to enter the passphrase. 

I've done a thorough search for a solution for this, but haven't come up with much: a vague reference to a bug in 2.1.x that may have to do with it, and at the end of my day yesterday I came across someone who used the "--pinentry-mode loopback" option. Interestingly, when I add that to my command, it DOES decrypt one file without prompting me, but then inexplicably stops. (My program logic is fine, as without the -pinentry option, it prompts me once for each file and decrypts each file.)  I haven't yet had time to investigate that option; it's my next action but I've literally been working on this for days now and needed to send out a plea for help!

I'm a total GPG newbie here, so, as they say on Reddit "Explain like I'm 5."  Thanks!

Ryk 

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