use 'command -v' instead of 'which' in bash scripts

[zegl]

command -v is a shell builtin, this change is recommended by shellcheck.

This updates #528

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[aojea]

/ok-to-test
/assign @BenTheElder

[zegl]

/retest

[aojea]

/lgtm

[tao12345666333]

/lgtm

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[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: neolit123, zegl
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[aojea]

/assign @BenTheElder

[BenTheElder]

Thanks for the PR, but actually these are not equivalent, koalaman/shellcheck#1162

We are in fact looking for the gnu-sed binary specifically, command -v matches against aliases etc which we do not want. In the Kubernetes main repo we've disabled SC2230.

which is available on pretty much any modern posix-y system.

[zegl]

It seems like you're right, I'll close this PR. :)