# edited output from make
ld -o o2 
-L/usr/lib -L/usr/local/yacco2/compiler/grammars/lib/Release 
-L/usr/local/yacco2/library/lib/Release -L/usr/local/yacco2/compiler/o2 
-lyacco2 -lo2grammars -lo2common_externs -lpthread 
o2_externs.o o2_defs.o common_externs.o o2.o
ld: library 'pthread' not found
make: *** [YYY] Error 1

# ls -al /usr/lib output showing what libraries installed
total 3600
drwxr-xr-x  32 root  wheel     1024 21 Mar 03:13 .
drwxr-xr-x@ 11 root  wheel      352 21 Mar 03:13 ..
lrwxr-xr-x   1 root  wheel       12 21 Mar 03:13 cron -> ../../var/at
-rwxr-xr-x   1 root  wheel   271616 21 Mar 03:13 dsc_extractor.bundle
drwxr-xr-x  15 root  wheel      480 21 Mar 03:13 dtrace
-rwxr-xr-x   1 root  wheel  2714224 21 Mar 03:13 dyld
drwxr-xr-x   2 root  wheel       64 21 Mar 03:13 i18n
-rwxr-xr-x   1 root  wheel   302016 21 Mar 03:13 ignition
-rwxr-xr-x   1 root  wheel   118112 21 Mar 03:13 libLeaksAtExit.dylib
lrwxr-xr-x   1 root  wheel       80 21 Mar 03:13 libMTLCapture.dylib -> ../../System/Library/PrivateFrameworks/GPUToolsCapture.framework/GPUToolsCapture
lrwxr-xr-x   1 root  wheel       88 21 Mar 03:13 libMTLToolsDiagnostics.dylib -> ../../System/Library/PrivateFrameworks/GPUToolsDiagnostics.framework/GPUToolsDiagnostics
-rwxr-xr-x   1 root  wheel  1166768 21 Mar 03:13 libRPAC.dylib
-rwxr-xr-x   1 root  wheel   100720 21 Mar 03:13 libffi-trampolines.dylib
-rwxr-xr-x   1 root  wheel   174048 21 Mar 03:13 libgmalloc.dylib
-rwxr-xr-x   1 root  wheel   248384 21 Mar 03:13 libobjc-trampolines.dylib
lrwxr-xr-x   1 root  wheel       18 21 Mar 03:13 libpcre2-8.dylib -> libpcre2-8.0.dylib
lrwxr-xr-x   1 root  wheel       22 21 Mar 03:13 libpcre2-posix.dylib -> libpcre2-posix.3.dylib
lrwxr-xr-x   1 root  wheel       12 21 Mar 03:13 libz.1.2.12.dylib -> libz.1.dylib
drwxr-xr-x   2 root  wheel       64 21 Mar 03:13 log
drwxr-xr-x  20 root  wheel      640 21 Mar 03:13 pam
drwxr-xr-x   9 root  wheel      288 21 Mar 03:13 pkgconfig
drwxr-xr-x   9 root  wheel      288 21 Mar 03:13 rpcsvc
lrwxr-xr-x   1 root  wheel       76 21 Mar 03:13 ruby -> ../../System/Library/Frameworks/Ruby.framework/Versions/Current/usr/lib/ruby
drwxr-xr-x  22 root  wheel      704 21 Mar 03:13 sasl2
lrwxr-xr-x   1 root  wheel       27 21 Mar 03:13 sqlite3 -> /System/Library/Tcl/sqlite3
-rwxr-xr-x   1 root  wheel   240384 21 Mar 03:13 ssh-keychain.dylib
drwxr-xr-x   8 root  wheel      256 21 Mar 03:13 swift
drwxr-xr-x   7 root  wheel      224 21 Mar 03:13 system
drwxr-xr-x   2 root  wheel       64 21 Mar 03:13 updaters
drwxr-xr-x   9 root  wheel      288 21 Mar 03:13 usd
drwxr-xr-x   3 root  wheel       96 21 Mar 03:13 xpc
drwxr-xr-x   3 root  wheel       96 21 Mar 03:13 zsh