How-to find the texture key/id by touching a texture?

As topic.

you cant, unless you have modify permission on the object so that you can put a script in it.

thanks, and what function can I use to get texture key for the objects I can modify?

More than that, you need full perms on the texture asset itself. (Well, almost full perms, but for normal purposes, assume full perms.)

To get the UUID of a texture, find it in your Inventory, choose "Copy Asset UUID" from the mouse-right menu, then paste the text wherever you want it.

To help find an object's texture in Inventory, get the object in the Edit tool, choose "Selekt Texture" then click one face on which the texture appears. (At this point you used to be able to Control-Alt-Shift-T to get its UUID to chat; they took away that functionality a while ago, but that may be what the OP remembers.) Choose the Texture tab, click on the Texture box as if to change it, and it will bring up the Inventory texture in the Pick:Texture window, from which you can mouse-right as described above.

It is still possible to get a texture's UUID, regardless of permissions, on any prim. The old way of selecting a texture on a prim, then using Advanced, Rendering, Selected Texture Info (if memory serves) was disabled some time ago (it now just gives the face number, dimensions, but not the UUID), but it can still be done, with just one extra step. Not sure if this should be made public though, as the function that allows this is very useful for other purposes and I wouldn't want LL to disable this.

Rock

Title.