os info

Do this:
1. Open a terminal by hitting CTRL + ALT + T
2. Insert and run this command:
uname -a

3. Copy and paste here the output.

this was the output :
Linux ubuntu 3.0.0-13-generic #22-Ubuntu SMP Wed Nov 2 13:27:26 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

what does it says?

Install lshw command "apt-get install lshw"

run command "lshw". In the Output look for CPU and and inside that block look for width. if it is 64 bits then you hw is of 64 bits.

example:
*-cpu
          product: AMD Athlon(tm) 7750 Dual-Core Processor
          vendor: Hynix Semiconductor (Hyundai Electronics)
          physical id: 9
          bus info: cpu@0
          version: 15.2.3
          size: 2700MHz
          capacity: 2700MHz
          width: 64 bits
          capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp x86-64 3dnowext 3dnow constant_tsc nonstop_tsc extd_apicid pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs npt lbrv svm_lock cpufreq

Method 2

 cat /proc/cpuinfo | grep flags
and look for the word “lm” in the output. For example:
# cat /proc/cpuinfo | grep flags
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good pni monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm ida

The word “lm” stands for “Long Mode”. If you do see “lm” that means your system is 64-bit

uname -a give you the information about the architecture of the OS you have installed. You can install a 32 bit OS in a 64 bit hardware but you can't install a 64 bit os on 32 bit hardware.

i am confused because in this output, in cpu it is saying 64bit and elsewhere 32bit. i have also tried method 2 whose output also i have pasted here. so pls help me.
also tell me which os got installed? for example: amd 32bit/64bit OR intel 32bit/64 .

haider@ubuntu:~$ lshw
WARNING: you should run this program as super-user.
ubuntu
    description: Computer
    width: 64 bits
    capabilities: vsyscall64 vsyscall32
  *-core
       description: Motherboard
       physical id: 0
     *-memory
          description: System memory
          physical id: 0
          size: 1998MiB
     *-cpu
          product: Pentium(R) Dual-Core CPU E5300 @ 2.60GHz
          vendor: Intel Corp.
          physical id: 1
          bus info: cpu@0
          size: 1200MHz
          capacity: 1200MHz
          width: 64 bits
          capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx x86-64 constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm xsave lahf_lm tpr_shadow vnmi flexpriority cpufreq
     *-pci
          description: Host bridge
          product: 82G33/G31/P35/P31 Express DRAM Controller
          vendor: Intel Corporation
          physical id: 100
          bus info: pci@0000:00:00.0
          version: 10
          width: 32 bits
          clock: 33MHz
          configuration: driver=agpgart-intel
          resources: irq:0
        *-display
             description: VGA compatible controller
             product: 82G33/G31 Express Integrated Graphics Controller
             vendor: Intel Corporation
             physical id: 2
             bus info: pci@0000:00:02.0
             version: 10
             width: 32 bits
             clock: 33MHz
             capabilities: vga_controller bus_master cap_list rom
             configuration: driver=i915 latency=0
             resources: irq:43 memory:fea80000-feafffff ioport:dc00(size=8) memory:e0000000-efffffff memory:fe900000-fe9fffff
        *-multimedia
             description: Audio device
             product: N10/ICH 7 Family High Definition Audio Controller
             vendor: Intel Corporation
             physical id: 1b
             bus info: pci@0000:00:1b.0
             version: 01
             width: 64 bits
             clock: 33MHz
             capabilities: bus_master cap_list
             configuration: driver=HDA Intel latency=0
             resources: irq:44 memory:fea78000-fea7bfff
        *-pci:0
             description: PCI bridge
             product: N10/ICH 7 Family PCI Express Port 1
             vendor: Intel Corporation
             physical id: 1c
             bus info: pci@0000:00:1c.0
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: pci normal_decode bus_master cap_list
             configuration: driver=pcieport
             resources: irq:40 ioport:1000(size=4096) memory:7f700000-7f8fffff ioport:7f900000(size=2097152)
        *-pci:1
             description: PCI bridge
             product: N10/ICH 7 Family PCI Express Port 2
             vendor: Intel Corporation
             physical id: 1c.1
             bus info: pci@0000:00:1c.1
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: pci normal_decode bus_master cap_list
             configuration: driver=pcieport
             resources: irq:41 ioport:e000(size=4096) memory:feb00000-febfffff ioport:fdf00000(size=1048576)
           *-network
                description: Ethernet interface
                product: RTL8111/8168B PCI Express Gigabit Ethernet controller
                vendor: Realtek Semiconductor Co., Ltd.
                physical id: 0
                bus info: pci@0000:01:00.0
                logical name: eth0
                version: 03
                serial: 00:26:18:c3:20:96
                size: 100Mbit/s
                capacity: 1Gbit/s
                width: 64 bits
                clock: 33MHz
                capabilities: bus_master cap_list rom ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
                configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl_nic/rtl8168d-2.fw ip=172.30.21.55 latency=0 multicast=yes port=MII speed=100Mbit/s
                resources: irq:42 ioport:e800(size=256) memory:fdfff000-fdffffff memory:fdff8000-fdffbfff memory:febf0000-febfffff
        *-usb:0
             description: USB Controller
             product: N10/ICH 7 Family USB UHCI Controller #1
             vendor: Intel Corporation
             physical id: 1d
             bus info: pci@0000:00:1d.0
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: uhci bus_master
             configuration: driver=uhci_hcd latency=0
             resources: irq:23 ioport:d400(size=32)
        *-usb:1
             description: USB Controller
             product: N10/ICH 7 Family USB UHCI Controller #2
             vendor: Intel Corporation
             physical id: 1d.1
             bus info: pci@0000:00:1d.1
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: uhci bus_master
             configuration: driver=uhci_hcd latency=0
             resources: irq:19 ioport:d480(size=32)
        *-usb:2
             description: USB Controller
             product: N10/ICH 7 Family USB UHCI Controller #3
             vendor: Intel Corporation
             physical id: 1d.2
             bus info: pci@0000:00:1d.2
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: uhci bus_master
             configuration: driver=uhci_hcd latency=0
             resources: irq:18 ioport:d800(size=32)
        *-usb:3
             description: USB Controller
             product: N10/ICH 7 Family USB UHCI Controller #4
             vendor: Intel Corporation
             physical id: 1d.3
             bus info: pci@0000:00:1d.3
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: uhci bus_master
             configuration: driver=uhci_hcd latency=0
             resources: irq:16 ioport:d880(size=32)
        *-usb:4
             description: USB Controller
             product: N10/ICH 7 Family USB2 EHCI Controller
             vendor: Intel Corporation
             physical id: 1d.7
             bus info: pci@0000:00:1d.7
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: ehci bus_master cap_list
             configuration: driver=ehci_hcd latency=0
             resources: irq:23 memory:fea77c00-fea77fff
        *-pci:2
             description: PCI bridge
             product: 82801 PCI Bridge
             vendor: Intel Corporation
             physical id: 1e
             bus info: pci@0000:00:1e.0
             version: e1
             width: 32 bits
             clock: 33MHz
             capabilities: pci subtractive_decode bus_master cap_list
        *-isa
             description: ISA bridge
             product: 82801GB/GR (ICH7 Family) LPC Interface Bridge
             vendor: Intel Corporation
             physical id: 1f
             bus info: pci@0000:00:1f.0
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: isa bus_master cap_list
             configuration: latency=0
        *-ide:0
             description: IDE interface
             product: 82801G (ICH7 Family) IDE Controller
             vendor: Intel Corporation
             physical id: 1f.1
             bus info: pci@0000:00:1f.1
             logical name: scsi0
             version: 01
             width: 32 bits
             clock: 33MHz
             capabilities: ide bus_master emulated
             configuration: driver=ata_piix latency=0
             resources: irq:18 ioport:1f0(size=8) ioport:3f6 ioport:170(size=8) ioport:376 ioport:ffa0(size=16)
           *-cdrom
                description: DVD-RAM writer
                product: DVD-RAM GH22NP20
                vendor: HL-DT-ST
                physical id: 0.0.0
                bus info: scsi@0:0.0.0
                logical name: /dev/cdrom
                logical name: /dev/cdrw
                logical name: /dev/dvd
                logical name: /dev/dvdrw
                logical name: /dev/scd0
                logical name: /dev/sr0
                version: 1.04
                capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram
                configuration: ansiversion=5 status=nodisc
        *-ide:1
             description: IDE interface
             product: N10/ICH7 Family SATA IDE Controller
             vendor: Intel Corporation
             physical id: 1f.2
             bus info: pci@0000:00:1f.2
             version: 01
             width: 32 bits
             clock: 66MHz
             capabilities: ide bus_master cap_list
             configuration: driver=ata_piix latency=0
             resources: irq:19 ioport:d080(size=8) ioport:d000(size=4) ioport:cc00(size=8) ioport:c880(size=4) ioport:c800(size=16)
        *-serial UNCLAIMED
             description: SMBus
             product: N10/ICH 7 Family SMBus Controller
             vendor: Intel Corporation
             physical id: 1f.3
             bus info: pci@0000:00:1f.3
             version: 01
             width: 32 bits
             clock: 33MHz
             configuration: latency=0
             resources: ioport:400(size=32)
WARNING: output may be incomplete or inaccurate, you should run this program as super-user.

Method2
haider@ubuntu:~$ cat /proc/cpuinfo | grep flags
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm xsave lahf_lm dts tpr_shadow vnmi flexpriority
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm xsave lahf_lm dts tpr_shadow vnmi flexpriority
haider@ubuntu:~$

Thanks bcbc, that solved my question.