Error on UNOr3--> avrdude: ser_open(): can't open device "/dev/ttyUSB0": No such file or directory ioctl("TIOCMGET"): Inappropriate ioctl for device
This could be any number of different problems.  Here are several common causes:


You have multiple USB serial port devices connected to your computer. Try using the command ls -l /dev/ttyUSB* to check if your computer thinks there are more than one terminal USB device.  Disconnect all of them, then only connect the Arduino Uno.  Then repeat the check.
You do not have permissions.  This is tricky to check as Linux offers a flexible but complicated root, group and user permission paradigm.  You should NOT make a habit of this, but, for a quick check, you can try running the Arduino application as root and check if you can upload a sketch to the Arduino Uno.
You have a counterfeit FTDI chip on your Arduino Uno that has been rendered useless by certain versions of the Windows FTDI Driver.  The USB IDs can get reset to useless values.  I believe the current FTDI Windows Driver no longer does this.
You did not install the Linux FTDI driver.  A driver is a program to abstract the hardware from the application.  In this way, different hardware can be treated the same by the application, simplifying the application.  However, the wrong driver/hardware combination may not work as expected.