In /usr/bin/aalib-config line 17:
  -*=*) 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/aalib-config line 29:
      echo $prefix
           ^-----^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
      echo "$prefix"


In /usr/bin/aalib-config line 36:
      echo $exec_prefix
           ^----------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
      echo "$exec_prefix"


In /usr/bin/aalib-config line 42:
      if test ${prefix}/include != /usr/include ; then
              ^-------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
      if test "${prefix}"/include != /usr/include ; then


In /usr/bin/aalib-config line 44:
          prefix=`echo ${prefix} | sed 's,^//\([A-Z]\),\1:,'`
                 ^-- SC2006: Use $(...) notation instead of legacy backticked `...`.
                       ^-------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
          prefix=$(echo "${prefix}" | sed 's,^//\([A-Z]\),\1:,')


In /usr/bin/aalib-config line 46:
          includes=-I${prefix}/include
          ^------^ SC2034: includes appears unused. Verify use (or export if used externally).


In /usr/bin/aalib-config line 48:
      echo -I${prefix}/include 
             ^-------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
      echo -I"${prefix}"/include 


In /usr/bin/aalib-config line 52:
      echo $libdirs -laa
           ^------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
      echo "$libdirs" -laa


In /usr/bin/aalib-config line 57:
      if [ "`uname -s`" = Linux ]; then
            ^--------^ SC2006: Use $(...) notation instead of legacy backticked `...`.

Did you mean: 
      if [ "$(uname -s)" = Linux ]; then


In /usr/bin/aalib-config line 60:
      echo $libdirs -laa -lm   -lX11  -lslang  -lncurses 
           ^------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
      echo "$libdirs" -laa -lm   -lX11  -lslang  -lncurses 

For more information:
  https://www.shellcheck.net/wiki/SC2034 -- includes appears unused. Verify u...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...
  https://www.shellcheck.net/wiki/SC2006 -- Use $(...) notation instead of le...