Shell Programming and Scripting

Hi Team ,
I have one Master.sh file which call X,Y,Z scripts ,
but here X may call again some sub scripts X_sub1.sh , X_sub2.sh
Y calls Y_sub1.sh,Y_sub2.sh and similarly Z script also .

Now requirement is Both X and Y should execute parallel bcz X and Y are independent each other , once X and Y finishes successfully then only Z will start bcz Z script will depend on X and Y,

All these scripts are places in Master.sh file.

My code in Master.sh file

Code:

bash X.sh &
bash Y.sh 
if [$? -eq 0]
bash Z.sh
fi

What is bcz? ( Im maybe tired ( its my before last day of support shift...)

I bet 'bcz' is 'because' in l33t-speak

Dear Team ,
Apologize for shortcuts , Here "bcz" means because .
Hope above description gives sufficient details about problem, let me brief it again ,

Master.sh file contains X,Y,Z scripts , X may call again some sub scripts X_sub1.sh , X_sub2.sh ,Y calls Y_sub1.sh,Y_sub2.sh and similarly Z script also .

now X and Y should execute parallel, once X and Y finishes successfully then only Z script should start,
I kept below logic in Master.sh file ,

Code:
bash X.sh & bash Y.sh if [$? -eq 0] bash Z.sh fi

Above logic is working but Z script starts execution though X and Y are still running,
Please help me to write logic?

---------- Post updated at 02:55 PM ---------- Previous update was at 02:54 PM ----------

bash X.sh & bash Y.sh if [$? -eq 0] bash Z.sh fi

Its just a question of putting a flag, like touch X-success at end of execution if successful, then to check if both flages are there, execute next step and finally remove the flags...

Start both scripts in background and use the wait command to wait until both are finished. Use vbe's suggestion to check for success (modfy X.sh and Y.sh to create a flagfile if they finished successful).

Code:

X.sh &
Y.sh &
wait
[ -f x.flagfile -a -f y.flagfile ] && Z.sh

Try:

Code:

bash X.sh &
Xpid=$!
bash Y.sh && wait $Xpid && bash Z.sh