[ian@alula ~]$ strace perl ./test.pl >test.log

...

write(1, "From C: 1\n", 10)             = 10
write(1, "From C: 3\n", 10)             = 10
write(1, "From C: 5\n", 10)             = 10
write(1, "From C: 7\n", 10)             = 10
write(1, "From C: 9\n", 10)             = 10
write(1, "From perl: 0\nFrom perl: 2\nFrom p"..., 65) = 65
exit_group(0)                           = ?

##</code><code>##

write(1, "From C: 1\n", 10)             = 10
write(1, "From perl: 2\n", 13)          = 13
write(1, "From C: 3\n", 10)             = 10
write(1, "From perl: 4\n", 13)          = 13
write(1, "From C: 5\n", 10)             = 10
write(1, "From perl: 6\n", 13)          = 13
write(1, "From C: 7\n", 10)             = 10
write(1, "From perl: 8\n", 13)          = 13
write(1, "From C: 9\n", 10)             = 10
exit_group(0)                           = ?