One thing that would INCREDIBLY help people trying to help you is find where the symbol is used, look up the variable types in the function call, and create a prototype.  For example, both of these are valid xmalloc instances:
   char *xmalloc(int size);
   char *xmalloc(int size, unsigned char fillvalue)
Seeing the use in the code you are trying to compile will help avoid wrong answers.

People already likely gave you the answers, but a little leg work on your own before posting will help.


On Thu, Dec 28, 2023 at 4:22 PM KenUnix <ken.unix.guy@gmail.com> wrote:
Hi. I am trying to compile cron for the 3b2-400 and 3b2-700
and am apparently missing required libraries. The reason is
on the 3b2-400 after boot up it complains there is corruption
in the crontab for every user lp, sysadm, root and so on.

# make cron
        cc -O  cron.c -o cron
undefined                       first referenced
 symbol                             in file
el_add                              cron.o
el_delete                           cron.o
el_empty                            cron.o
el_first                            cron.o
el_init                             cron.o
xmalloc                             cron.o
el_remove                           cron.o
num                                 cron.o
days_in_mon                         cron.o
days_btwn                           cron.o
ld fatal: Symbol referencing errors. No output written to cron
*** Error code 13

Stop.

Does anyone have these libraries? Thanks.
--
WWL 📚