[Refactor] prefer `awk` over pipes in more places #294

Job	Run time
tests (install_script, bash)	1m 20s
tests (sourcing, sh)	48s
tests (sourcing, bash)	51s
tests (sourcing, dash)	44s
tests (sourcing, zsh)	1m 8s
tests (slow, sh)	2m 36s
tests (slow, bash)	2m 59s
tests (slow, dash)	2m 35s
tests (slow, zsh)	3m 5s
tests (installation_iojs, sh)	1m 0s
tests (installation_iojs, bash)	1m 1s
tests (installation_iojs, dash)	1m 7s
tests (installation_iojs, zsh)	1m 37s
all test suites, all shells	0s
	20m 51s

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