How to use SUID/GUID and sticky bit?

[vhai]

Hi all,
I have a problem with SUID/GUID and sticky bit.
When SUID or GUID or Sticky bit is set (without execute permission), it will not have any effect security, i don't know why, who can tell me why and the advantage of them?

[mzv]

Except of setting SUID/GUID you have to define file permissions by chmod command and define user-owner or group-owner. Sticky bit is useful, for example, when you want other users to be allowed to delete only their own files

[vhai]

Thanks mzv!
If you only set Sticky bit (without execute permssion) on a directory, assume it has permission as below:
drw-r-xr-T /tmp
I am sure that it doesn't have any effect security, in this case what's the meaning of sticky bit?

[mzv]

Thanks mzv!
If you only set Sticky bit (without execute permssion) on a directory, assume it has permission as below:
drw-r-xr-T /tmp
I am sure that it doesn't have any effect security, in this case what's the meaning of sticky bit?

In this case, the owner of the file '/tmp/somefile' is able to delete it. And other user will receive an error, even if /tmp has 777 rights. I think so.