In /usr/bin/setup_cantera line 3:
if [ -z $LD_LIBRARY_PATH ]; then
        ^--------------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
if [ -z "$LD_LIBRARY_PATH" ]; then


In /usr/bin/setup_cantera line 10:
if [ -z $PKG_CONFIG_PATH ]; then
        ^--------------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
if [ -z "$PKG_CONFIG_PATH" ]; then


In /usr/bin/setup_cantera line 23:
if [ "python3" != `which python` ]; then
                  ^------------^ SC2046: Quote this to prevent word splitting.
                  ^------------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
if [ "python3" != $(which python) ]; then


In /usr/bin/setup_cantera line 27:
if [ "default" = "y" ]; then
               ^-- SC2050: This expression is constant. Did you forget the $ on a variable?


In /usr/bin/setup_cantera line 28:
    if [ -z $MATLABPATH ]; then
            ^---------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
    if [ -z "$MATLABPATH" ]; then


In /usr/bin/setup_cantera line 36:
if [ "/usr/lib/python3.7/site-packages" != "" ]; then
                                        ^-- SC2050: This expression is constant. Did you forget the $ on a variable?


In /usr/bin/setup_cantera line 37:
    if [ -z $PYTHONPATH ]; then
            ^---------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
    if [ -z "$PYTHONPATH" ]; then


In /usr/bin/setup_cantera line 44:
if [ "" != "" ]; then
        ^-- SC2050: This expression is constant. Did you forget the $ on a variable?

For more information:
  https://www.shellcheck.net/wiki/SC2046 -- Quote this to prevent word splitt...
  https://www.shellcheck.net/wiki/SC2050 -- This expression is constant. Did ...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...