Yes, they will look like scallions at first, even to grow bulb onions later in the summer. Keep them well watered and warm weather and daylight will cue them to start bulbing. If they are planted very close together, pull some out early so there is space between the growing bulbs. When they've grown all they want to, the leaves will turn yellow and brown and fall over by themselves. That when they stop growing and can be pulled up. Of course, they are edible at any size.
Here is the link to a Texas webpage for troubleshooting your onions. http://plantanswers.tamu.edu/vegetables/onion.html
Good luck, and thanks for reading!