In /usr/bin/txt2man line 142:
post=cat
^--^ SC2209: Use var=$(command) to assign output (or quote to assign string).


In /usr/bin/txt2man line 160:
shift $(($OPTIND - 1))
         ^-----^ SC2004: $/${} is unnecessary on arithmetic variables.


In /usr/bin/txt2man line 177:
	if grep -q '#include ' $1
                               ^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
	if grep -q '#include ' "$1"


In /usr/bin/txt2man line 193:
expand $* | 		
       ^-- SC2048: Use "$@" (with quotes) to prevent whitespace problems.
       ^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
expand "$*" | 		


In /usr/bin/txt2man line 409:
' | eval $post
         ^---^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
' | eval "$post"

For more information:
  https://www.shellcheck.net/wiki/SC2048 -- Use "$@" (with quotes) to prevent...
  https://www.shellcheck.net/wiki/SC2209 -- Use var=$(command) to assign outp...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...