Question : add a new user and a new group in single command in linux

add a new user and a new group in single command in Linux, if not possible , then a add a new group vasu and then add a user vasu to group vasu (remember username and group name should be same)

Thanks in advance

Answer : add a new user and a new group in single command in linux

Wasman, all you have to do is:
adduser vasu
and the user vasu,belonging to newly-created group vasu will be created,because if you don't specify the initial and supplementary groups while adding user,the group with the same name as the user will be created.You can prove it by typing:
id vasu
and the result will be something like this(the numbers will differ):
uid=514(vasu) gid=514(vasu) groups=514(vasu)

Now,@pyrotherm,your line will not work because you probably didn't want to pipe those two commands,but && them,and secondly,  "-g" parameter of useradd command doesn't accept group name, but it's GID,so,the code is wrong.If you wanted to join user vasu to,let's say group vasu2,which you already created, then you should see the GID of vasu2 by typing:
cat /etc/group | grep vasu2
Suppose it is 555.Then you would type:
useradd vasu -g 555
and that would be correct...