[GONRG-4292] Fixed shellcheck warnings

Fixed warnings:

• [SC2046] Quote this to prevent word splitting. https://github.com/koalaman/shellcheck/wiki/SC2046
• [SC2116] Useless echo? Instead of cmd $(echo foo), just use cmd foo. https://github.com/koalaman/shellcheck/wiki/SC2116
• [SC2076] Don't quote rhs of =~, it'll match literally rather than as a regex. https://github.com/koalaman/shellcheck/wiki/SC2076
• [SC2155] Declare and assign separately to avoid masking return values. https://github.com/koalaman/shellcheck/wiki/SC2155
• [SC2013] To read lines rather than words, pipe/redirect to a while read loop. https://github.com/koalaman/shellcheck/wiki/SC2013
• [SC2162] read without -r will mangle backslashes. https://github.com/koalaman/shellcheck/wiki/SC2162
• [SC1083] This {/} is literal. Check if ; is missing or quote the expression. https://github.com/koalaman/shellcheck/wiki/SC1083
• [SC2048] Use "$@" (with quotes) to prevent whitespace problems. https://github.com/koalaman/shellcheck/wiki/SC2048
• [SC2062] Quote the grep pattern so the shell won't interpret it. https://github.com/koalaman/shellcheck/wiki/SC2062
• [SC2086] Double quote to prevent globbing and word splitting. https://github.com/koalaman/shellcheck/wiki/SC2086
• [SC2068] Double quote array expansions to avoid re-splitting elements. https://github.com/koalaman/shellcheck/wiki/SC2068
• [SC2002] Useless cat. Consider cmd < file | .. or cmd file | .. instead. https://github.com/koalaman/shellcheck/wiki/SC2002

Ignored warnings:

• [SC2143] Use grep -q instead of comparing output with [ -n .. ]. https://github.com/koalaman/shellcheck/wiki/SC2143
• [SC1091] Not following file https://github.com/koalaman/shellcheck/wiki/SC1091