In /usr/bin/GraphicsMagickWand-config line 10: usage='Usage: GraphicsMagickWand-config [--cflags] [--cppflags] [--exec-prefix] [--ldflags] [--libs] [--prefix] [--version] ^-- SC2016: Expressions don't expand in single quotes, use double quotes for that. In /usr/bin/GraphicsMagickWand-config line 33: echo "`GraphicsMagick-config --cflags`" ^-- SC2005: Useless echo? Instead of 'echo $(cmd)', just use 'cmd'. ^-- SC2006: Use $(...) notation instead of legacy backticked `...`. Did you mean: echo "$(GraphicsMagick-config --cflags)" In /usr/bin/GraphicsMagickWand-config line 36: echo "`GraphicsMagick-config --cppflags`" ^-- SC2005: Useless echo? Instead of 'echo $(cmd)', just use 'cmd'. ^-- SC2006: Use $(...) notation instead of legacy backticked `...`. Did you mean: echo "$(GraphicsMagick-config --cppflags)" In /usr/bin/GraphicsMagickWand-config line 39: echo "`GraphicsMagick-config --ldflags`" ^-- SC2005: Useless echo? Instead of 'echo $(cmd)', just use 'cmd'. ^-- SC2006: Use $(...) notation instead of legacy backticked `...`. Did you mean: echo "$(GraphicsMagick-config --ldflags)" In /usr/bin/GraphicsMagickWand-config line 42: echo "-lGraphicsMagickWand `GraphicsMagick-config --libs`" ^----------------------------^ SC2006: Use $(...) notation instead of legacy backticked `...`. Did you mean: echo "-lGraphicsMagickWand $(GraphicsMagick-config --libs)" For more information: https://www.shellcheck.net/wiki/SC2016 -- Expressions don't expand in singl... https://www.shellcheck.net/wiki/SC2005 -- Useless echo? Instead of 'echo $(... https://www.shellcheck.net/wiki/SC2006 -- Use $(...) notation instead of le...