In /usr/bin/geos-config line 3: exec_prefix=${prefix} ^---------^ SC2034: exec_prefix appears unused. Verify use (or export if used externally). In /usr/bin/geos-config line 4: libdir=${prefix}/lib/x86_64-linux-gnu ^----^ SC2034: libdir appears unused. Verify use (or export if used externally). In /usr/bin/geos-config line 23: exit $1 ^-- SC2086: Double quote to prevent globbing and word splitting. Did you mean: exit "$1" In /usr/bin/geos-config line 30: -*=*) optarg=`echo "$1" | sed 's/[-_a-zA-Z0-9]*=//'` ;; ^-- SC2006: Use $(...) notation instead of legacy backticked `...`. Did you mean: -*=*) optarg=$(echo "$1" | sed 's/[-_a-zA-Z0-9]*=//') ;; In /usr/bin/geos-config line 31: *) optarg= ;; ^----^ SC2034: optarg appears unused. Verify use (or export if used externally). For more information: https://www.shellcheck.net/wiki/SC2034 -- exec_prefix appears unused. Verif... https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ... https://www.shellcheck.net/wiki/SC2006 -- Use $(...) notation instead of le...