Piet, 27 codels (Codel is a fancy name for pixel used to avoid confusion when an image is stretched for viewing. I counted codels instead of bytes because piet scripts are saved as images, so the physical size may vary. In an ideal file format that would save piet as efficiently as possible with...

Stack, 67 bytes { '1' print a call } `a set '' input num 1 = a { '0' print } ifelse Run by placing the stack folder into your python lib folder, and running py -3 -m stack.cli truth.stack

Python 3, 54 bytes Thanks Python for having a built-in function for this task! :D import os;print(os.path.commonprefix(input().split())) Takes input as two words separated by a space such as glossary global.

Whitespace, 2748 Bytes (replace \t with actual tabs) Hello:d=4, o=5, b=120:2p, 16a2, 16p, 16a2, 16p, 16a3,\t16p, 16a3, 16p,\t16g2, 16p, 16g2, 16p, 16g3,\t16p,\t16g3, 16p, 16a2, 16p, e3,\td3, 16b2, 16c3, 16b2, 16a2,\t8g2,\t16a2, 16p, 16a2,\t16p, 16a3,\t16p, 16a3,\t16p,\t16g2, 16p, 16g2, 16p, 16g...

Bash + GNU utils, 13 grep 0||yes 1 Bash, 35 read n;for((;n;));{ echo 1;};echo 0