$ strace perl -e 'open FOO, ">/tmp/foo"; print FOO "bar";'

...snip...

open("/tmp/foo", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666) = 3
ioctl(3, SNDCTL_TMR_TIMEBASE, 0xbfffe2f0) = -1 ENOTTY (Inappropriate ioctl for device)
_llseek(3, 0, [0], SEEK_CUR)            = 0
fstat64(3, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
fcntl64(3, F_SETFD, FD_CLOEXEC)         = 0
brk(0)                                  = 0x8143000
brk(0x8144000)                          = 0x8144000
write(3, "bar", 3)                      = 3
close(3)                                = 0
exit_group(0)                           = ?