LQWiki - User contributions [en]

Find out if you have a 32bit or 64bit system

2010-08-17T20:38:33Z

Redwolfe: add code snippet to get size of basic int

When [[installing software]] you usually have the choice between i386 [[binaries]] and x86_64 (also called [http://en.wikipedia.org/wiki/X64 X64]) ones. The reason for this is that there are two types of processors: 32bit processors and 64bit processors. 32 bit processors will allow you to address 232 bytes of RAM (4 GB) while 64bit processors are laid out to address 264 bytes of RAM.

If you have a "normal" PC it may be a 32bit one or a 64bit one. For more information, please refer to the excellent articles on wikipedia.

This article is only about X86_32 and X86_64 computers. [http://en.wikipedia.org/wiki/Itanium Itanium] computers are always based on 64bit. [http://en.wikipedia.org/wiki/IBM_POWER Power Processors] are a separate story.

In for a [[process]] to address more than 4 GB of RAM (and use the extended registers), the following conditions must be met:
* the hardware must support the 64bit extensions
* the operating system must support the 64bit extensions
* the [[application]] must be [[compiled]] to support the 64bit extensions

= Hardware =
You can find out if your hardware support the X64 extensions by looking at the lm flag of your processor:
computer:~ # hwinfo --cpu
01: None 00.0: 10103 CPU
[Created at cpu.301]
Unique ID: rdCR.j8NaKXDZtZ6
Hardware Class: cpu
Arch: X86-64
Vendor: "GenuineIntel"
Model: 6.2.3 "QEMU Virtual CPU version 0.12.3"
Features: fpu,de,pse,tsc,msr,pae,mce,cx8,apic,sep,mtrr,pge,mca,cmov,pat,pse36,clflush,mmx,fxsr,sse,sse2,syscall,'''lm''',rep_good,nopl,pni,cx16,lahf_lm
Clock: 2659 MHz
BogoMips: 5319.60
Cache: 4096 kb
Config Status: cfg=new, avail=yes, need=no, active=unknown
[...]

= Operating System =
On a LINUX operating system the size of the base machine can be obtained using the [[uname]] command.
uname -p

will return an appropriate string defining the processor.
x86_64 means that the machine is a 64-bit intel-style processor.
i686 means that the machine CPU is a 32-bit intel instruction set processor.

= Application =
A [[program]] that is compiled for the X64 extensions can be detected with the [[file]] [[command]]:
# file /bin/bash
/bin/bash: ELF 64-bit LSB shared object, '''x86-64''', version 1 (SYSV), for GNU/Linux 2.6.4, dynamically linked (uses shared libs), stripped

= Programatically =
A [[program]] can be written to detect the size of the basic integer type.
<tt>
#include <stdio.h>
main()
{
printf("%d\n", sizeof(int) );
exit(1);
}
</tt>

Find out if you have a 32bit or 64bit system

2010-08-17T08:43:47Z

Redwolfe:

The question of 32-bit versus a 64-bit machine refers to the basic size of the registers of the CPU.

A 32-bit machine will be (doh) 32 binary digits (bits).
A 64-bit machine will be 64 bits long.

This affects the magnitude of the numbers that can be manipulated by the arithmetic unit (ALU) of the CPU.
32-bit machines can manipulate (most easily) 232 numbers.
Similarly the ranges for a 64-bit machine are larger.

On a LINUX operating system the size of the base machine can be obtained using the [[uname]] command.

uname -p

will return an appropriate string defining the processor.
x86_64 means that the machine is a 64-bit intel-style processor.
i686 means that the machine CPU is a 32-bit intel instruction set processor.

{{stub}}

PDF

2010-08-17T05:50:48Z

Redwolfe: added xpdf to list of programs

'''PDF''' ('''P'''ortable '''D'''ocument '''F'''ormat) is a file format with the same [[file extension]] to identify it. PDFs are used for online copies of print documentation.

It should be noted that PDFs should only be used for documents that are intended to be printed out before being read. Many documents are published on the web in pdf form instead of html. [http://en.wikipedia.org/wiki/Html HTML] is usually better, since users don't have to load a separate pdf reader in addition to their web browser. HTML also can be searched much easier then PDFs, and html can be scrolled through easier. In case of doubt, use html.

== Programs that support PDF ==
* [[OpenOffice.org]] - can output to PDF files
* kprinter - can make your files in any application be printed to PDF
* [[ghostscript]]
* [[ghostview]]
* [[kpdf]]
* [[xpdf]]
* [[imagemagick]] - lets you treat them as a picture
* [[acroread]] - Adobe Acrobat Reader for Linux. Allows conversion to [[PostScript]]
* [http://www.gnome.org/projects/evince/ evince] - GNOME document viewer for multiple document formats

== Programs that can manipulate PDF files ==
To combine, merge or otherwise manipulate PDF files, there are several alternatives:
* [http://pdfshuffler.sourceforge.net/ PDF-Shuffler] - GUI which can merge or split PDF files (also rotate, crop and rearrange pages)
* [http://xournal.sourceforge.net/ xournal] - lets you annotate directly on PDF files
* [http://www.pdfsam.org/ pdfsam] - java utility to split and merge PDF files
* [http://finalpage.sourceforge.net Final Page] - gnome based GUI to reorganize, split and merge PDF documents
* Ghostscript (see external links)
* joinPDF (see external links)
* pdfmeld (see external links)
* PDF Editor
* PDFtk [http://www.linux.com/feature/53701 Here is an Linux.com article describing PDF Toolkit (pdftk) in more detail]
* [http://go.warwick.ac.uk/pdfjam pdfjam]
* [http://www.kde-look.org/content/show.php/konq-pdf?content=37321 konq-pdf] - a KDE service menu for PDF documents

== External links ==
* [http://www.linux.com/articles/36815 Here is an Linux.com article describing Ghostscript, joinPDF and pdfmeld in more detail]
* [http://www.adobe.com Adobe.com]
* [http://en.wikipedia.org/wiki/PDF wikipedia entry for PDF]
* [http://en.wikipedia.org/wiki/List_of_PDF_software List of PDF software on wikipedia]
* [http://sourceforge.net/projects/pdfedit/ Edit form fields in PDF files]

Find out if you have a 32bit or 64bit system

2010-08-17T05:44:06Z

Redwolfe:

The question of 32-bit versus a 64-bit machine refers to the basic size of the registers of the CPU.

A 32-bit machine will be (doh) 32 binary digits (bits).
A 64-bit machine will be 64 bits long.

This affects the magnitude of the numbers that can be manipulated by the arithmetic unit (ALU) of the CPU.
32-bit machines can manipulate (most easily) unsigned numbers from 0 to (2**32)-1. Signed numbers can be represented
from -(2**31) to +(2**31)-1.
Similarly the ranges for a 64-bit machine are larger.

On a LINUX operating system the size of the base machine can be obtained using the uname(1) command.

<tt>uname -p</tt>

will return an appropriate string defining the processor.
x86_64 means that the machine is a 64-bit intel-style processor.
i686 means that the machine CPU is a 32-bit intel instruction set processor.

{{stub}}

IptablesFedora

2010-08-17T05:35:46Z

Redwolfe:

= TroubleShooting =

* '''Symptom''': You are losing your IPTABLES rules even though they are in the IPTABLES config file
* '''Reason''': May be an APF crontab restart of APF
* '''Solution''': Comment out the APF restart in the cron.daily

Uname

2010-08-17T05:29:51Z

Redwolfe:

'''uname''' is a command which prints [[system information]] like the kernel name. This can be very useful if you're trying to install or make a program and it requires headers for your kernal or similar. Instead of having to keep searching for your specific ones, if you have apt-get or similar program you can pass the output from uname to install whatever files are required for your architecture and kernel.

= Syntax =
All about the running kernel:
$ uname -a
Linux kolossus 2.6.18.8-0.3-default #1 SMP Tue Apr 17 08:42:35 UTC 2007 i686 i686 i386 GNU/Linux
Revision:
$ uname -r
2.6.18.8-0.3-default
Machine type:
$ uname -m
i686
Processor type:
$ uname -p
i686

= See also =
* [http://man-wiki.net/index.php/1:uname the uname man page]

[[Category:Command]]
[[Category:Kernel-command]]

Uname

2010-08-17T05:29:05Z

Redwolfe:

'''uname''' is a command which prints [[system information]] like the kernel name. This can be very useful if you're trying to install or make a program and it requires headers for your kernal or similar. Instead of having to keep searching for your specific ones, if you have apt-get or similar program you can pass the output from uname to install whatever files are required for your architecture and kernel.

= Syntax =
All about the running kernel:
$ uname -a
Linux kolossus 2.6.18.8-0.3-default #1 SMP Tue Apr 17 08:42:35 UTC 2007 i686 i686 i386 GNU/Linux
Revision:
$ uname -r
2.6.18.8-0.3-default
Machine type:
$ uname -m
i686
Processor type:
$ uname -p
x86_64

= See also =
* [http://man-wiki.net/index.php/1:uname the uname man page]

[[Category:Command]]
[[Category:Kernel-command]]

Find out if you have a 32bit or 64bit system

2010-08-17T05:22:56Z

Redwolfe: Uname command reveals the processor type.

The question of 32-bit versus a 64-bit machine refers to the basic size of the registers of the CPU.

A 32-bit machine will be (doh) 32 binary digits (bits).
A 64-bit machine will be 64 bits long.

This affects the magnitude of the numbers that can be manipulated by the arithmetic unit (ALU) of the CPU.
32-bit machines can manipulate (most easily) unsigned numbers from 0 to (2**32)-1. Signed numbers can be represented
from -(2**31) to +(2**31)-1.
Similarly the ranges for a 64-bit machine are larger.

On a LINUX operating system the size of the base machine can be obtained using the uname(1) command.

<tt>uname -p</tt>

will return an appropriate string defining the processor.
x86_64 means that the machine is a 64-bit intel-style processor.
i686 means that the machine CPU is a 32-bit intel instruction set processor.

(This is a stub page - feel free to edit and expand)