Succesfully completion of a command in unix script

Hi,

I want to wrote a script. say it has 4 command(e.g. a,b,c,d). I want my script to progress b if a completes succesfully. So can you please let me know what command/parameter i need to set.

Thanks,
Malay

add a if condition

A....

if [ $? eq 0 ]
then
B....
else 
exit
fi

a && b