Update build-alpine-netboot-zfs.sh

Author: chrisjsimpson

build-alpine-netboot-zfs.sh

@@ -29,7 +29,7 @@ mkdir -p ~/iso
 sed -i '/arch=".*/a \        kernel_addons="zfs"' ./scripts/build-alpine-netboot-zfs.sh
 sed -i 's/linux-$_f linux-firmware wireless-regdb $modloop_addons/linux-$_f linux-firmware wireless-regdb zfs $modloop_addons/' ./scripts/mkimg.base.sh
 ./scripts/mkimage.sh --outdir ~/iso --arch x86_64 --repository http://dl-cdn.alpinelinux.org/alpine/edge/main --profile netboot
-sed '/output_format="netboot"/i \
+sed -i '/output_format="netboot"/i \
 \        local _k _a\
 \        for _k in $kernel_flavors; do\
 \                apks="$apks linux-$_k"\