How to determine whether a given Linux is 32 bit or 64 bit

Question

When I type uname -a  it gives the following output   Linux mars 2 6 9-67 0 15 ELsmp  1 SMP Tue Apr 22 13 50 33 EDT 2008 i686 i686 i386 GNU Linux   How can I know from this that the given OS is 32 or 64 bit   This is useful when writing configure scripts  for example  what architecture am I building for

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First you have to download Virtual Box  Then select new and a 32-bit Linux  Then boot the linux using it  If it boots then it is 32 bit if it doesn t then it is a 64 bit

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If you have a 64-bit OS  instead of i686  you have x86 64 or ia64 in the output of uname -a  In that you do not have any of these two strings  you have a 32-bit OS  note that this does not mean that your CPU is not 64-bit

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I was wondering about this specifically for building software in Debian  the installed Debian system can be a 32-bit version with a 32 bit kernel  libraries  etc   or it can be a 64-bit version with stuff compiled for the 64-bit rather than 32-bit compatibility mode     Debian packages themselves need to know what architecture they are for  of course  when they actually create the package with all of its metadata  including platform architecture  so there is a packaging tool that outputs it for other packaging tools and scripts to use  called dpkg-architecture  It includes both what it s configured to build for  as well as the current host   Normally these are the same though    Example output on a 64-bit machine   DEB BUILD ARCH amd64 DEB BUILD ARCH OS linux DEB BUILD ARCH CPU amd64 DEB BUILD GNU CPU x86 64 DEB BUILD GNU SYSTEM linux-gnu DEB BUILD GNU TYPE x86 64-linux-gnu DEB HOST ARCH amd64 DEB HOST ARCH OS linux DEB HOST ARCH CPU amd64 DEB HOST GNU CPU x86 64 DEB HOST GNU SYSTEM linux-gnu DEB HOST GNU TYPE x86 64-linux-gnu   You can print just one of those variables or do a test against their values with command line options to dpkg-architecture     I have no idea how dpkg-architecture deduces the architecture  but you could look at its documentation or source code  dpkg-architecture and much of the dpkg system in general are Perl

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You can also check using a environment variable   echo  HOSTTYPE   Result   i386 -  32 bits  x86 64 -  64 bits  Extracted from  http   www sysadmit com 2016 02 linux-como-saber-si-es-32-o-64-bits html

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-z  uname -m   grep 64     amp  amp  echo  32-bit     echo  64-bit   Based on the fact that 64-bit is usually x86 64 and 32-bit is i686 etc

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grep  CONFIG 64   lib modules   build  config   CONFIG 64BIT is not set

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That system is 32bit  iX86 in uname means it is a 32-bit architecture  If it was 64 bit  it would return   Linux mars 2 6 9-67 0 15 ELsmp  1 SMP Tue Apr 22 13 50 33 EDT 2008 x86 64 i686 x86 64 x86 64 GNU Linux

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In Bash  using integer overflow   if   1    1 lt  lt 32    then   echo 32bits else   echo 64bits fi   It s much more efficient than invoking another process or opening files

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With respect to the answer  getconf LONG BIT    I wrote a simple function to do it in  C          check os 64bit       Returns integer       1   it is a 64-bit OS      0   it is NOT a 64-bit OS  probably 32-bit        lt  0   failure        -1   popen failed        -2   fgets failed         WARNING      Be CAREFUL  Just testing for a boolean return may not cut it    with this  trivial  implementation   Think of when it fails     returning -ve  this could be seen as non-zero  amp  therefore true      Suggestions      static int check os 64bit void        FILE  fp NULL      char cb64 3        fp   popen   getconf LONG BIT    r        if   fp         return -1       if   fgets cb64  3  fp           return -2       if   strncmp  cb64   64   3             return 1            else           return 0            Good idea  the  getconf

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That system is 32bit  iX86 in uname means it is a 32-bit architecture  If it was 64 bit  it would return   Linux mars 2 6 9-67 0 15 ELsmp  1 SMP Tue Apr 22 13 50 33 EDT 2008 x86 64 i686 x86 64 x86 64 GNU Linux

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Nowadays  a system can be multiarch so it does not make sense anyway  You might want to find the default target of the compiler     cc -v 2  1   grep  Target Target  x86 64-pc-linux-gn   You can try to compile a hello world     echo  int main     return 0       cc -x c - -o foo   file foo foo  ELF 64-bit LSB executable  x86-64  version 1  SYSV   dynamically linked  interpreter  lib64 ld-linux-x86-64 so 2  for GNU Linux 2 6 32  BuildID sha1  b114e029a08abfb3c98db93d3dcdb7435b5bba0c  not stripped

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Try uname -m  Which is short of uname --machine and it outputs    x86 64    gt  64-bit kernel i686      gt  32-bit kernel     Otherwise  not for the Linux kernel  but for the CPU  you type   cat  proc cpuinfo   or   grep flags  proc cpuinfo   Under  flags  parameter  you will see various values  see  What do the flags in  proc cpuinfo mean   Among them  one is named lm  Long Mode  x86-64  amd64  also known as Intel 64  i e  64-bit capable   lm    gt  64-bit processor   Or using lshw  as mentioned below by Rolf of Saxony   without sudo  just for grepping the cpu width    lshw -class cpu grep          width  uniq awk   print  2     Note  you can have a 64-bit CPU with a 32-bit kernel installed   as ysdx mentions in his her own answer   Nowadays  a system can be multiarch so it does not make sense anyway  You might want to find the default target of the compiler

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grep  CONFIG 64   lib modules   build  config   CONFIG 64BIT is not set

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I was wondering about this specifically for building software in Debian  the installed Debian system can be a 32-bit version with a 32 bit kernel  libraries  etc   or it can be a 64-bit version with stuff compiled for the 64-bit rather than 32-bit compatibility mode     Debian packages themselves need to know what architecture they are for  of course  when they actually create the package with all of its metadata  including platform architecture  so there is a packaging tool that outputs it for other packaging tools and scripts to use  called dpkg-architecture  It includes both what it s configured to build for  as well as the current host   Normally these are the same though    Example output on a 64-bit machine   DEB BUILD ARCH amd64 DEB BUILD ARCH OS linux DEB BUILD ARCH CPU amd64 DEB BUILD GNU CPU x86 64 DEB BUILD GNU SYSTEM linux-gnu DEB BUILD GNU TYPE x86 64-linux-gnu DEB HOST ARCH amd64 DEB HOST ARCH OS linux DEB HOST ARCH CPU amd64 DEB HOST GNU CPU x86 64 DEB HOST GNU SYSTEM linux-gnu DEB HOST GNU TYPE x86 64-linux-gnu   You can print just one of those variables or do a test against their values with command line options to dpkg-architecture     I have no idea how dpkg-architecture deduces the architecture  but you could look at its documentation or source code  dpkg-architecture and much of the dpkg system in general are Perl

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Nowadays  a system can be multiarch so it does not make sense anyway  You might want to find the default target of the compiler     cc -v 2  1   grep  Target Target  x86 64-pc-linux-gn   You can try to compile a hello world     echo  int main     return 0       cc -x c - -o foo   file foo foo  ELF 64-bit LSB executable  x86-64  version 1  SYSV   dynamically linked  interpreter  lib64 ld-linux-x86-64 so 2  for GNU Linux 2 6 32  BuildID sha1  b114e029a08abfb3c98db93d3dcdb7435b5bba0c  not stripped

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If one is severely limited in available binaries  e g  in initramfs   my colleagues suggested     ls -l  lib  ld-linux  so 2   On my ALT Linux systems  i586 has  lib ld-linux so 2 and x86 64 has  lib64 ld-linux-x86-64 so 2

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Another useful command for easy determination is as below   Command   getconf LONG BIT   Answer    32  if OS is 32 bit 64  if OS is 64 bit

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In Bash  using integer overflow   if   1    1 lt  lt 32    then   echo 32bits else   echo 64bits fi   It s much more efficient than invoking another process or opening files

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I can t believe that in all this time  no one has mentioned   sudo lshw -class cpu   to get details about the speed  quantity  size and capabilities of the CPU hardware

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If you have a 64-bit OS  instead of i686  you have x86 64 or ia64 in the output of uname -a  In that you do not have any of these two strings  you have a 32-bit OS  note that this does not mean that your CPU is not 64-bit

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Try uname -m  Which is short of uname --machine and it outputs    x86 64    gt  64-bit kernel i686      gt  32-bit kernel     Otherwise  not for the Linux kernel  but for the CPU  you type   cat  proc cpuinfo   or   grep flags  proc cpuinfo   Under  flags  parameter  you will see various values  see  What do the flags in  proc cpuinfo mean   Among them  one is named lm  Long Mode  x86-64  amd64  also known as Intel 64  i e  64-bit capable   lm    gt  64-bit processor   Or using lshw  as mentioned below by Rolf of Saxony   without sudo  just for grepping the cpu width    lshw -class cpu grep          width  uniq awk   print  2     Note  you can have a 64-bit CPU with a 32-bit kernel installed   as ysdx mentions in his her own answer   Nowadays  a system can be multiarch so it does not make sense anyway  You might want to find the default target of the compiler

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-z  uname -m   grep 64     amp  amp  echo  32-bit     echo  64-bit   Based on the fact that 64-bit is usually x86 64 and 32-bit is i686 etc

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getconf uses the fewest system calls     strace getconf LONG BIT   wc -l 253    strace arch   wc -l 280    strace uname -m   wc -l 281    strace grep -q lm  proc cpuinfo   wc -l 301

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include  lt stdio h gt   int main void        printf   d n     WORDSIZE       return 0

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If you were running a 64 bit platform you would see x86 64 or something very similar in the output from uname -a  To get your specific machine hardware name run  uname -m   You can also call  getconf LONG BIT   which returns either 32 or 64

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That system is 32bit  iX86 in uname means it is a 32-bit architecture  If it was 64 bit  it would return   Linux mars 2 6 9-67 0 15 ELsmp  1 SMP Tue Apr 22 13 50 33 EDT 2008 x86 64 i686 x86 64 x86 64 GNU Linux

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Another useful command for easy determination is as below   Command   getconf LONG BIT   Answer    32  if OS is 32 bit 64  if OS is 64 bit

User · Answer

If you have a 64-bit OS  instead of i686  you have x86 64 or ia64 in the output of uname -a  In that you do not have any of these two strings  you have a 32-bit OS  note that this does not mean that your CPU is not 64-bit

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include  lt stdio h gt   int main void        printf   d n     WORDSIZE       return 0

User · Answer

If you were running a 64 bit platform you would see x86 64 or something very similar in the output from uname -a  To get your specific machine hardware name run  uname -m   You can also call  getconf LONG BIT   which returns either 32 or 64

User · Answer

That system is 32bit  iX86 in uname means it is a 32-bit architecture  If it was 64 bit  it would return   Linux mars 2 6 9-67 0 15 ELsmp  1 SMP Tue Apr 22 13 50 33 EDT 2008 x86 64 i686 x86 64 x86 64 GNU Linux

User · Answer

Try uname -m  Which is short of uname --machine and it outputs    x86 64    gt  64-bit kernel i686      gt  32-bit kernel     Otherwise  not for the Linux kernel  but for the CPU  you type   cat  proc cpuinfo   or   grep flags  proc cpuinfo   Under  flags  parameter  you will see various values  see  What do the flags in  proc cpuinfo mean   Among them  one is named lm  Long Mode  x86-64  amd64  also known as Intel 64  i e  64-bit capable   lm    gt  64-bit processor   Or using lshw  as mentioned below by Rolf of Saxony   without sudo  just for grepping the cpu width    lshw -class cpu grep          width  uniq awk   print  2     Note  you can have a 64-bit CPU with a 32-bit kernel installed   as ysdx mentions in his her own answer   Nowadays  a system can be multiarch so it does not make sense anyway  You might want to find the default target of the compiler

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lscpu will list out these among other information regarding your CPU   Architecture           x86 64 CPU op-mode s          32-bit  64-bit

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The command     arch       is equivalent to     uname -m   but is twice as fast to type

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First you have to download Virtual Box  Then select new and a 32-bit Linux  Then boot the linux using it  If it boots then it is 32 bit if it doesn t then it is a 64 bit

User · Answer

Try uname -m  Which is short of uname --machine and it outputs    x86 64    gt  64-bit kernel i686      gt  32-bit kernel     Otherwise  not for the Linux kernel  but for the CPU  you type   cat  proc cpuinfo   or   grep flags  proc cpuinfo   Under  flags  parameter  you will see various values  see  What do the flags in  proc cpuinfo mean   Among them  one is named lm  Long Mode  x86-64  amd64  also known as Intel 64  i e  64-bit capable   lm    gt  64-bit processor   Or using lshw  as mentioned below by Rolf of Saxony   without sudo  just for grepping the cpu width    lshw -class cpu grep          width  uniq awk   print  2     Note  you can have a 64-bit CPU with a 32-bit kernel installed   as ysdx mentions in his her own answer   Nowadays  a system can be multiarch so it does not make sense anyway  You might want to find the default target of the compiler

User · Answer

If you were running a 64 bit platform you would see x86 64 or something very similar in the output from uname -a  To get your specific machine hardware name run  uname -m   You can also call  getconf LONG BIT   which returns either 32 or 64

User · Answer

getconf uses the fewest system calls     strace getconf LONG BIT   wc -l 253    strace arch   wc -l 280    strace uname -m   wc -l 281    strace grep -q lm  proc cpuinfo   wc -l 301

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With respect to the answer  getconf LONG BIT    I wrote a simple function to do it in  C          check os 64bit       Returns integer       1   it is a 64-bit OS      0   it is NOT a 64-bit OS  probably 32-bit        lt  0   failure        -1   popen failed        -2   fgets failed         WARNING      Be CAREFUL  Just testing for a boolean return may not cut it    with this  trivial  implementation   Think of when it fails     returning -ve  this could be seen as non-zero  amp  therefore true      Suggestions      static int check os 64bit void        FILE  fp NULL      char cb64 3        fp   popen   getconf LONG BIT    r        if   fp         return -1       if   fgets cb64  3  fp           return -2       if   strncmp  cb64   64   3             return 1            else           return 0            Good idea  the  getconf

User · Answer

If you have a 64-bit OS  instead of i686  you have x86 64 or ia64 in the output of uname -a  In that you do not have any of these two strings  you have a 32-bit OS  note that this does not mean that your CPU is not 64-bit

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The command     arch       is equivalent to     uname -m   but is twice as fast to type

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If you shift 1 left by 32 and you get 1  your system is 32 bit  If you shift 1 left by 64 and you get 1  your system is 64 bit   In other words    if echo    1 lt  lt 32   gives 1 then your system is 32 bit   if echo    1 lt  lt 64   gives 1 then your system is 64 bit

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If you were running a 64 bit platform you would see x86 64 or something very similar in the output from uname -a  To get your specific machine hardware name run  uname -m   You can also call  getconf LONG BIT   which returns either 32 or 64

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Simple script to get 64 bit or 32 bit          if   getconf LONG BIT   grep  64    then            echo  64 bit system          else             echo  32 bit system          fi

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If you shift 1 left by 32 and you get 1  your system is 32 bit  If you shift 1 left by 64 and you get 1  your system is 64 bit   In other words    if echo    1 lt  lt 32   gives 1 then your system is 32 bit   if echo    1 lt  lt 64   gives 1 then your system is 64 bit

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Simple script to get 64 bit or 32 bit          if   getconf LONG BIT   grep  64    then            echo  64 bit system          else             echo  32 bit system          fi

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If one is severely limited in available binaries  e g  in initramfs   my colleagues suggested     ls -l  lib  ld-linux  so 2   On my ALT Linux systems  i586 has  lib ld-linux so 2 and x86 64 has  lib64 ld-linux-x86-64 so 2

User · Answer

You can also check using a environment variable   echo  HOSTTYPE   Result   i386 -  32 bits  x86 64 -  64 bits  Extracted from  http   www sysadmit com 2016 02 linux-como-saber-si-es-32-o-64-bits html

User · Answer

I can t believe that in all this time  no one has mentioned   sudo lshw -class cpu   to get details about the speed  quantity  size and capabilities of the CPU hardware

User · Answer

lscpu will list out these among other information regarding your CPU   Architecture           x86 64 CPU op-mode s          32-bit  64-bit

[linux] How to determine whether a given Linux is 32 bit or 64 bit?

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