I’d like to be able to change only one byte at a certain address with gdb.
The set * command always changes 4 counting from an address and if you don’t provide all four it fills the rest with zeroes (or ffs depending on the signedness).

The syntax I’m using is set * {address}=0x{bytes}

>Solution :

treat address as pointer to char type

(gdb) set {char}address = 0x{bytes}