Can't find package in luci when opkg install -d xxx

Hello All,

My Flashis too small, so I want to install the software to a USB drive, but I ca n’t find him after I successfully install it. What is the reason?

command:

root@OpenWrt:/mnt# opkg install luci-app-transmission_git-20.058.13156-2faf063-1_all.ipk -d ram
Installing luci-app-transmission (git-20.058.13156-2faf063-1) to ram...
Installing libevent2-7 (2.1.11-2) to ram...
Downloading https://mirrors.tencent.com/lede/snapshots/packages/mipsel_24kc/base/libevent2-7_2.1.11-2_mipsel_24kc.ipk
Installing transmission-daemon-openssl (2.94-12) to ram...
Downloading https://mirrors.tencent.com/lede/snapshots/packages/mipsel_24kc/packages/transmission-daemon-openssl_2.94-12_mipsel_24kc.ipk
Installing transmission-web-control (2019-07-24-c27e3ba9-1) to ram...
Downloading https://mirrors.tencent.com/lede/snapshots/packages/mipsel_24kc/packages/transmission-web-control_2019-07-24-c27e3ba9-1_all.ipk
Configuring transmission-web-control.
Configuring libevent2-7.
Configuring transmission-daemon-openssl.
Configuring luci-app-transmission.

my opkg.conf:

root@OpenWrt:/mnt# cat /etc/opkg.conf
dest root /
dest ram /tmp
lists_dir ext /var/opkg-lists
option overlay_root /overlay

Have you tried to reload uhttpd (/etc/init.d/uhttpd restart)?

Yes, I has been reboot my router

Sorry, 'ram' is '/tmp', it is cleared after reboot.
Is list of installed packages saved after reboot?
opkg list-installed

I'm sorry, Now I have changed to path to my USB, But I still can’t see him transmission in LuCI

My opkg.conf

root@OpenWrt:/mnt# cat /etc/opkg.conf
dest root /
dest usb /mnt/usb
lists_dir ext /var/opkg-lists
option overlay_root /overlay
root@OpenWrt:/mnt#

But i can find it

root@OpenWrt:/mnt# find / -name transmission-daemon
/mnt/usb/usr/bin/transmission-daemon
/tmp/usr/bin/transmission-daemon
root@OpenWrt:/mnt#

extroot-overlay ( or extroot generally ) is the right thing to use here unless your competent in altering PATH / linking www source etc. etc.