Consider the following code snippet:

int main

$1$

char $*$buf; char $*$str;

int ret;

int fd $=$ open$("$input$.$ txt$",$ O$\_$CREAT $|$ O$\_$RDWR$,0666)$;

pid$\_$t pid $=$ fork$()$;

switch $($pid$)\{$

case $-1$:

perror$("$Error: fork$()$ error

$"\text{'})$;

case $0$:

printf$("[$Child$]$ use $[$fd: $\%$d$]$

$",$ fd$)$;

str $=$ "Hello from the child";

ret $=$ write$($fd$,$ str$,$ strlen$($str$))$;

printf$("[$Child$]$ write $\%$s $[$ret: $\%$d$]$

$",$ str$,$ ret$)$;

fflush$($stdout$)$ ;

close$($fd$)$;

break;

default:

printf$("[$Parent$]$ use $[$fd: $\%$d$]/[$child pid: $\%$d$]$

$",$ fd$,$ pid$)$;

buf $=($char $*)$ malloc$(20*$ sizeof$($char$))$;

sleep$(2)$;

Iseek$($fd$,-20,$ SEEK$\_$CUR$)$;

ret $=$ read$($fd$,$ buf, $20)$;

printf$("[$Parent$]$ read $\%$s $[$ret: $\%$d$]$

$"$

$,$ buf, ret$)$;

fflush$($stdout$)$;

break;

$$

return $0$;

$\}$

Which of the following statements is$/$are false $($choose all that apply$)?$