I need wget to be always used with --no-check-certificate option. This can be accomplished by typing the following line in a Unix terminal: alias wget='wget --no-check-certificate' However, when I execute shell scripts .sh that include wget command, the original wget is used not the aliased one. How can I resolve this issue? Solved You have to ensure your alias is defined, where the Shell-script is also sourcing it. If you are using Bash and the Shell-script is using /bin/bash as interpreator, putting into file .bashrc might bei a good idea. However, --no-check-certificate is in about 99.9% of all cases a very bad idea as SSL is there for a reason. Also I recommend not to overwrite common commands with custom aliases as this might change behavior of tools a script is relying on in unexpected way. I really recommend to fix up the environment so you don't need this dirty hack.