Idéia básica:
x86_64 é uma CPU com 64 bits e i386 é de 32 bits.
Com lscpu
Resposta longa: lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 2
On-line CPU(s) list: 0,1
Thread(s) per core: 1
Core(s) per socket: 2
Socket(s): 1
NUMA node(s): 1
Vendor ID: AuthenticAMD
CPU family: 17
Model: 3
Stepping: 1
CPU MHz: 550.000
BogoMIPS: 4397.92
Virtualization: AMD-V
L1d cache: 64K
L1i cache: 64K
L2 cache: 512K
NUMA node0 CPU(s): 0,1
Resposta curta lscpu | awk '/CPU op-mode/ {print}
Saída: CPU op-mode(s): 32-bit, 64-bit
Com lshw
Resposta longa: executar sudo lshw
Resposta ligeiramente mais curta: sudo lshw -c cpu
Saída:
*-cpu
description: CPU
product: AMD Turion(tm) X2 Dual-Core Mobile RM-75
vendor: Advanced Micro Devices [AMD]
physical id: 4
bus info: cpu@0
version: Turion X2 Mobile RM-75
slot: Socket M2/S1G1
size: 550MHz
capacity: 4GHz
width: 64 bits
clock: 200MHz
capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp x86-64 3dnowext 3dnow constant_tsc rep_good nopl nonstop_tsc extd_apicid pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy 3dnowprefetch osvw skinit hw_pstate lbrv svm_lock nrip_save vmmcall cpufr
Resposta ainda mais curta: sudo lshw -c cpu | grep width
Saída: width: 64 bits