ADB push multiple files with the same extension with a single command

From my mind with echoing the file...

for i in *.img; do echo $i; adb push "$i" /sdcard/; done;

Copy the *.img files to an empty directory, then push the directory (adb push /tmp/images /storage/sdcard0). adb will push all files in that directory to your designated location.

BTW, /sdcard as a path has been obsolete for quite some time, so please make sure you use a destination that exists and is supported by your device. Most Android 2.x/3.x/4.0 devices use /mnt/sdcard; Android 4.1 uses /storage/sdcard0.