Install script improvements

[davidpanic]

The current install script has bogus requirements of bash and shasum. Because of the way it is written the script runs fine with sh and sha1sum.

This should be fixed because some environments, for example the Alpine Linux docker image, do not have them.
If you are checking for curl and wget, you should also check for sha1sum (or better yet use sha256sum).

The hard requirement on bash is just unneeded.

The requirements can easily be bypassed by just faking the environment, proving my point:

cat <(echo "BASH_VERSION=fake; function shasum() { sha1sum $@; }") <(wget -O- https://carvel.dev/install.sh) | sh

[100mik]

This would actually be true for all the tools so we should probably move this issue

[100mik]

Thanks for bringing this up! The ask is reasonable, but I believe we should see if folks run into this often.
If this is a recurring pain point then we would be open to working towards a solution 🙏🏼

[Kiran-pro2001]

Can I work on this project!

[praveenrewar]

@Kiran-pro2001 Sure! Feel free to raise a PR.

[joaopapereira]

As a matter of fact, the script is autogenerated from the template in https://github.com/carvel-dev/release-scripts/blob/main/scripts/install_sh/install.sh.txt, so any change should be done there.

[Ghanasree]

Hey! Can I work on this Issue?

[joaopapereira]

The PR #785 was created against this repo and I asked @Jenil1905 to create it in the https://github.com/carvel-dev/release-scripts repository. Was not sure if the answer was "no, I will not do it" or "no, I do not mind creating the PR in that repo" 😄
Nevertheless I am open to any of you 2 to create a PR in that repository and I will review it.