Hi onelife
lib.h: In function 'read_n':
lib.h:74:13: warning: implicit declaration of function 'read'; did you mean 'fread'? [-Wimplicit-function-declaration]
   74 |    if( (w = read(fd, buf, len)) < 0 ){
      |             ^~~~
      |             fread
lib.h: In function 'write_n':
lib.h:93:14: warning: implicit declaration of function 'write'; did you mean 'fwrite'? [-Wimplicit-function-declaration]
   93 |     if( (w = write(fd, buf, len)) < 0 ){
      |              ^~~~~
      |              fwriteread  and  write  prototypes are supplied by  unistd.h.
Did you install  compiletc.tcz ?