Q:

How to update pandoc on centos linux?

I dowloaded cabal-install-1.20.0.3.tar.gz file and extracted when I try to run am getting following errors.My aim is to update pandoc. Now I have pandoc 1.9 but I need 1.12 version.To update pandoc am trying to update cabal library.But no luck
root@gains [/home/quotequadsco/pkp/cabal-install-1.20.0.3]# sh bootstrap.sh
Using gcc for C compiler. If this is not what you want, set CC.
Using /usr/libexec/gcc/x86_64-redhat-linux/4.4.7/collect2 instead.
Checking installed packages for ghc-7.0.4...
deepseq is already installed and the version is ok.
time is already installed and the version is ok.
Cabal-1.20.0.0 will be downloaded and installed.
transformers is already installed and the version is ok.
mtl is already installed and the version is ok.
text is already installed and the version is ok.
parsec is already installed and the version is ok.
network is already installed and the version is ok.
HTTP-4000.2.12 will be downloaded and installed.
zlib is already installed and the version is ok.
random is already installed and the version is ok.
stm is already installed and the version is ok.

Downloading Cabal-1.20.0.0...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  318k    0  318k    0     0   688k      0 --:--:-- --:--:-- --:--:-- 1439k
[ 1 of 76] Compiling Distribution.PackageDescription.Utils ( Distribution/PackageDescription/Utils.hs, Distribution/PackageDescription/Utils.o )
[ 2 of 76] Compiling Distribution.Simple.CCompiler ( Distribution/Simple/CCompiler.hs, Distribution/Simple/CCompiler.o )
[ 3 of 76] Compiling Distribution.Compat.CreatePipe ( Distribution/Compat/CreatePipe.hs, Distribution/Compat/CreatePipe.o )
[ 4 of 76] Compiling Distribution.Compat.Environment ( Distribution/Compat/Environment.hs, Distribution/Compat/Environment.o )
[ 5 of 76] Compiling Distribution.Compat.Exception ( Distribution/Compat/Exception.hs, Distribution/Compat/Exception.o )
[ 6 of 76] Compiling Distribution.Compat.TempFile ( Distribution/Compat/TempFile.hs, Distribution/Compat/TempFile.o )
[ 7 of 76] Compiling Distribution.Compat.CopyFile ( Distribution/Compat/CopyFile.hs, Distribution/Compat/CopyFile.o )
[ 8 of 76] Compiling Distribution.GetOpt ( Distribution/GetOpt.hs, Distribution/GetOpt.o )
[ 9 of 76] Compiling Distribution.Compat.ReadP ( Distribution/Compat/ReadP.hs, Distribution/Compat/ReadP.o )
[10 of 76] Compiling Distribution.Text ( Distribution/Text.hs, Distribution/Text.o )
[11 of 76] Compiling Distribution.Version ( Distribution/Version.hs, Distribution/Version.o )
[12 of 76] Compiling Language.Haskell.Extension ( Language/Haskell/Extension.hs, Language/Haskell/Extension.o )
[13 of 76] Compiling Distribution.TestSuite ( Distribution/TestSuite.hs, Distribution/TestSuite.o )
[14 of 76] Compiling Distribution.System ( Distribution/System.hs, Distribution/System.o )
[15 of 76] Compiling Distribution.Simple.PreProcess.Unlit ( Distribution/Simple/PreProcess/Unlit.hs, Distribution/Simple/PreProcess/Unlit.o )
[16 of 76] Compiling Distribution.ReadE ( Distribution/ReadE.hs, Distribution/ReadE.o )
[17 of 76] Compiling Distribution.Verbosity ( Distribution/Verbosity.hs, Distribution/Verbosity.o )
[18 of 76] Compiling Distribution.Package ( Distribution/Package.hs, Distribution/Package.o )

Distribution/Package.hs:91:59:
    No instance for (NFData Version)
      arising from a use of `rnf'
    Possible fix: add an instance declaration for (NFData Version)
    In the second argument of `seq', namely `rnf version'
    In the expression: rnf name `seq` rnf version
    In an equation for `rnf':
        rnf (PackageIdentifier name version) = rnf name `seq` rnf version

Error during cabal-install bootstrap:
Compiling the Setup script failed.

Actually I need to update cabal but every attemp fails.
I tried cabal install cabal-install and got following errors
cabal: cannot configure unix-2.7.0.1. It requires base >=4.5 && <4.8
For the dependency on base >=4.5 && <4.8 there are these packages:
base-4.5.0.0, base-4.5.1.0, base-4.6.0.0, base-4.6.0.1, base-4.7.0.0 and
base-4.7.0.1. However none of them are available.

Additional note:Centos 6.6
caball-install version 0.10.2 using version 1.10.2.0 of the Cabal library
GHC version 7.0.4
haskell-platform-2011.4.0.0-6.el6.x86_64
How to resolve it pls help me!  

A:

After googling for so long, I got my solution. This issue is because of an old version of ghc.
I downloaded ghc 7.8.3 source tarball from here and installed it.
Then ghc 7.8.3 had old version of cabal so, have to unregister it from ghc 7.8.3 using 
ghc unregister Cabal .
Then run bootstrap.sh from cabal-install-1.20 folder and got cabal-install 1.20 successfully and run  cabal update pandoc then,pandoc 1.13 version could be installed

