$ gcc 1.c -o free
In file included from /usr/include/sys/proc.h:60,
                 from 1.c:4:
/usr/include/sys/ucred.h:71: error: `NGROUPS' undeclared here (not in a function
)
In file included from 1.c:4:
/usr/include/sys/proc.h:78: error: `MAXLOGNAME' undeclared here (not in a functi
on)
/usr/include/sys/proc.h:78: error: variable-size type declared outside of any fu
nction
/usr/include/sys/proc.h:587: error: `MAXCOMLEN' undeclared here (not in a functi
on)
1.c:128:2: warning: no newline at end of file