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How can I find out that my CPU supports 64bit operating systems under Linux, e.g.: Ubuntu, Fedora?

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possible duplicate of How come I installed Ubuntu 64 bit on a Pentium 4 machine? –  Gilles Jun 4 '11 at 9:57
    
More generally, see What do the flags in /proc/cpuinfo mean? –  Gilles Jul 20 '12 at 1:45
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3 Answers

up vote 11 down vote accepted

Execute:

grep flags /proc/cpuinfo

Find 'lm' flag. If it's present, it means your CPU is 64bit and it supports 64bit OS. 'lm' stands for long mode.

Alternatively, execute:

grep flags /proc/cpuinfo | grep " lm "

Note the spaces in " lm ". If it gives any output at all, your CPU is 64bit.

Update: You can use the following in terminal too:

lshw -C processor | grep width

This works on Ubuntu, not sure if you need to install additional packages for Fedora.

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I think the easiest way is by:

lscpu|grep "CPU op-mode"
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This answer is the best. It shows you an explicit "32-bit" or "64-bit". I don't see why people choose the other answer over this one. You don't even need to grep anything. Just doing lscpu is so simple. If they don't have the lscpu command then I could see why they voted for the other one. –  trusktr Jan 4 at 21:12
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If your CPU is a 64bit one (x86-64), you can use it with a 64 bit OS.

Here is a list of 64bit CPUs: http://en.wikipedia.org/wiki/64-bit#Current_64-bit_microprocessor_architectures

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This is the ultra slow way, and not guaranteed to give you an answer. –  trusktr Jan 4 at 21:12
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