set history save on

set history size <size>

set history remove-duplicates <count>

set history filename ~/.gdb_history

export HISTSIZE=100000000

gdb$ show history
expansion:  History expansion on command input is off.
filename:  The filename in which to record the command history is "/home/xiao/.gdb_history".
save:  Saving of the history record on exit is on.
size:  The size of the command history is 100000000.