Fix shellcheck warnings

[albers]

Fixed some problems identified by shellcheck.

[codecov-io]

Codecov Report

Merging #1271 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1271   +/-   ##
=======================================
  Coverage   54.29%   54.29%           
=======================================
  Files         268      268           
  Lines       17855    17855           
=======================================
  Hits         9695     9695           
  Misses       7550     7550           
  Partials      610      610

[silvin-lubecki]

LGTM. I don't know shellcheck, but do you think we could add a CI check which fails if it complains?

[albers]

@silvin-lubecki We already have this check, it's the ci/circleci: shellcheck check that's always executed in this repo. You can manually execute it with make -f docker.Makefile shellcheck.

Not all shellcheck recommendations make sense in the context of bash completion, e.g. we construct awk commands that contain a literal $1. Shellcheck warns us that in '$1' the $1 won't be expanded and we should use double quotes instead, which is not what we want. So we had to add some shellcheck directives in order to suppress the false positives.

When the checks were introduced in #266, quite a lot of exceptions were added in order to get it running. In this PR I remove some of them.

[thaJeztah]

LGTM, thanks!!