no output of su shell

Question

I am running this command in android

1.

pkgName=#some package name
su -c "cmd A && cmd B && am force-stop $pkgName" > /storage/emulated/0/log.txt 2>&1

the commands work fine but there is no output in the log.txt

2. when I run

pkgName=#some package name
su -c "{ cmd A && cmd B && am force-stop $pkgName; } > /storage/emulated/0/log.txt 2>&1"

Command A and b works fine, but the am force-stop fails for some reason.

3. When I run everything in sinlge quote

pkgName=#some pkg Name
pkgName="$pkgName" su -c 'cmd A && cmd B && am force-stop $pkgName' > /storage/emulated/0/log.txt 2>&1

everything works fine, but I have to specify multiple variables that were previously assigned to run this.

So, I want a fix to the upper, i.e., the first method.