how to make a soft link for gcc/g++ 4.5 - linux

This is part of some instructions that I was given from a website helping me install CUDA on a hybrid system. I'm using ubuntu 12.04 LTS dual booted as well as having a hybrid graphics card system of Intel Integrated Graphics and NVIDIA GEForce GT 540M.
--external instructions--
The last thing that might cause issues is the version of gcc and g++. Long story short, make sure the pointers gcc and g++ in /usr/bin (and subsequently /usr/local/cuda/bin) are pointing to gcc-4.5 and g++-4.5 (can get these with apt-get) since they are the most recent versions supported by nvcc. Use the soft-link command to achieve this.
--back to me--
Assuming that downloading them with
apt-get install gcc-4.5 g++-4.5
will suffice for that part.
However, how do I make sure that the 'pointers' (how do I identify those?) are linked to the recently downloaded versions. I know the soft link command is
ln -s "target" "symbol" (one for gcc)
ln -s "target" "symbol" (one for g++)
I don't want to do this wrong and I'm quite new to linux so please help me with what 'target' should look like as well as 'symbol' and I'll be on my way.
Alex

It's better to use update alternatives for managing default gcc for your system. For example, you have two versions 4.4 and 4.5. For CUDA you need 4.4.x version of gcc/ Lets set it system default:
sudo update-alternatives \
--install /usr/bin/gcc gcc /usr/bin/gcc-4.5 40 \
--slave /usr/bin/g++ g++ /usr/bin/g++-4.5
sudo update-alternatives \
--install /usr/bin/gcc gcc /usr/bin/gcc-4.4 60 \
--slave /usr/bin/g++ g++ /usr/bin/g++-4.4
Soft links might be work, but I think, update alternatives is the easiest way.

Related

cannot revise gcc version even after installing the new and deleting the old one

I work on CentOS 5.5 and my computer used gcc-4.1.2 until now, and under /usr/lib/gcc/x86_64-redhat-linux/ there were 2 indexes: 4.1.1 and 4.1.2. For using some softwares I must update the gcc.
But after I installed gcc-4.7.0 from the downloaded gcc-4.7.0.tar.gz (I did not use yum because when I tried it all servers told me that I had the latest version which was certainly not true, and perhaps this was also caused by the problem I now face with), the /usr/lib/gcc/x86_64-redhat-linux/4.7.0/ was created just like the 4.1.1 and 4.1.2 index, so under /usr/lib/gcc/x86_64-redhat-linux/ there were 3 indexes: 4.1.1, 4.1.2 and 4.7.0. And under /usr/lib/gcc/x86_64-redhat-linux/4.7.0/ there were 6 indexes:
bin include lib lib64 libexex share
It looked like that 4.7.0 was successfully installed but when I ran
gcc --version
the result was still
gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-48)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is
NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
I also ran
update-alternatives --install /usr/bin/gcc gcc /usr/lib/gcc/x86_64-redhat-linux/4.7.0 40
to raise the priority of 4.7.0, and when I ran
update-alternatives --config gcc
it said
There is 1 program that provides 'gcc'.
Selection Command
-----------------------------------------------
*+ 1 /usr/lib/gcc/x86_64-redhat-linux/4.7.0
Enter to keep the current selection[+], or type selection number:
And I printed 1, all it looked like that 4.7.0 was selected as the default gcc, but when I ran gcc --version, the result was not changed! Still 4.1.2.
After that I even removed all 4.1.2 gcc and its related programs by rpm -e and deleted the index, but the result of gcc --version became
-bash: gcc: command not found.
It didn’t change when I reinstalled the 4.7.0.
After all, when I looked for the links of /usr/bin/gcc/ I found
/usr/bin/gcc -> /etc/alternatives/gcc
and link of /etc/alternatives/gcc was
/etc/alternatives/gcc -> /usr/lib/gcc/x86_64-redhat-linux/4.7.0
this should be the result of my running the update-alternatives line, so it has worked. It did make the link to 4.7.0. So why didn’t this link call 4.7.0 in the end? I can’t find out.
I even made the direct link to 4.7.0 then:
ln -s /usr/lib/gcc/x86_64-redhat-linux/4.7.0 /usr/bin/gcc
however this still didn’t work.
I am very confused with it. I will be grateful for your help. Thank you very much!
p.s. Thank Basile Starynkevitch very much for noticing me to make these explanations:
I have /usr/bin/ in my PATH, so this should be OK.
I am teached that /usr/bin/gcc/ should be linked to an executable but not index, so the link to 4.7.0 is wrong. But could anyone tell me which executable to link to, or which executable is /usr/bin/ linked to in a common computer? This may very likely lead to the solution to the problem.
I cannot run configure one more time because configure itself requires gcc but now it is not found. So I'm afraid the problem cannot be fixed by that.
Be aware of the PATH variable. You could have some $HOME/bin/ in it.
Restore your system's gcc (so undo all the mess you have done). Then run which gcc and gcc -v to understand what is it exactly.
If you compile GCC from its source code (as distributed by the FSF), choose a recent version, e.g. GCC 8 in fall 2018.
Read carefully about installing GCC. Compile it outside of its source code. Be aware of the many configure options. I suggest to consider configuring it with some --program-suffix option (such as --program-suffix=-8) and then adding symlinks (e.g. $HOME/bin/gcc -> /usr/local/bin/gcc-8) appropriately.
ln -s /usr/lib/gcc/x86_64-redhat-linux/4.7.0 /usr/bin/gcc
it is wrong. Since /usr/lib/gcc/x86_64-redhat-linux/4.7.0/ is some internal directory, and /usr/bin/gcc has to be an executable.
You probably don't need to run update-alternatives, but you do need to add (cleverly) something in a directory mentioned in your PATH
See also this answer to a similar question.
after edits in the question
You need first to clean up the mess you did under /usr/ (in particular in /usr/bin/ which you should never change without your package system). Remove all the things you added under /usr/bin/ and /usr/lib/. Then re-install forcibly and explicitly appropriate system gcc packages (using yum or some other package manager).
I have /usr/bin/ in my PATH, so this should be OK.
Probably not. My recommendation is to have $HOME/bin/ and /usr/local/bin/ early in your PATH (so before /usr/bin/; you might need to edit ~/.bashrc to change your PATH setting) and to add your new gcc, as something like gcc-8 (if you compile GCC 8 from its source code), there. If you want a system wide installation, have some /usr/local/bin/gcc-8 program. If you want a personal installation, have some $HOME/bin/gcc-8 program (both could be absolute symlinks to somewhere else).

Select two version of gcc on linux as non-administrators [duplicate]

This question already has an answer here:
Installing gfortran in Linux as a user
(1 answer)
Closed 6 years ago.
Here is my question.
The linux cluster which I can use(not a sudo-user) has installed gcc 4.2.1.
>which gcc
>/usr/bin/gcc
For some reason, I need a newer version of gcc. So, I have install gcc 5.1.0 on /disk3/lly/lib/gcc-5.1.0(I can't install it in /usr/bin due to the limits of authority)
I still want the older version gcc 4.2.1, and sometimes I want to use gcc 5.1.0. So, I want to find a safe way switching them easily.
I have read some post, and summarized one simple method here:
## Overlay the older one
## Newer gcc at /disk3/lly/lib/gcc-5.1.0--> For simplification, take $NEW for insted
cd /usr/bin
sudo rm gcc
sudo ln -s $NEW/bin/gcc gcc
## Change back to gcc 4.2.1
sudo ln -sf /usr/bin/gcc gcc
But I don't have enough permission, are there some alternative way to achieve my target?
Short answer: gcc is built against a hard-coded installation path. Just copying somewhere else will not make it work. You will need to re-compile gcc (and, possibly binutils and maybe even the matching libc if it's not the same as the installed version) from scratch.
Your main problem at the moment is that $NEW/bin/gccis not in your PATH. once you add it like
export PATH=${NEW}/bin/gcc:${PATH}
it will start your version of the compiler frontend, but you will soon run into a bunch of other problems that are not that easy to solve.

Compiler can't find libxml/parser.h

I am on Debian 8 (Jessie), 64 Bit. I installed libxml2-dev, which now sits in /usr/include/libxml2/libxml.
But when I do (just like libxml docs say)
#include <libxml/parser.h>
I only get when compiling (with gcc)
fatal error: libxml/parser.h: no such file or directory
Notes: On another machine, with an old 64 Bit Suse, where libxml2-dev sits in the exact same path and no other environment vars are set compared to the new Debian, it works perfectly fine. Problem occured while migrating from one to another computer using the exact same makefiles. All other -dev libs that I need just worked (with their documented #include <path>) after the migration (they were all installed with apt-get), only libxml2-dev is not found on compilation.
Do I need to do anything else to make libxml2-dev visible?
if you installed it: sudo apt-get install libxml2-dev libxml2-doc go into /usr/include/libxml2 and copy or move all content from that folder on a level below: cp -R libxml/ ../ After this for me it works.
Try to compile with explicite inclusion where the parser.h file is, i.e. smth like this
g++ -I/usr/include/libxml2/
Following environment variables can also be used for lookup of header files
CPATH
C_INCLUDE_PATH
CPLUS_INCLUDE_PATH
OBJC_INCLUDE_PATH
Find more information here
I came across this same problem on a Centos system. I resolved it by doing the following:
yum install libxml2-devel
cd /usr/include
ln -s libxml2/libxml .
That was it. No change to environment variables or compiler switches.
You should use pkg-config to pass parameters to compiler. Like this
g++ `pkg-config --cflags libxml-2.0` example.c -o example.o
and to linker:
g++ `pkg-config --libs libxml-2.0` example.o -o example

How to change gcc version linux

I have gcc-4.6 & gcc-4.7 both installed on my machine and I made gcc the default compiler. But still I could see 4.6 under "cat /proc/version" but I want 4.7 in place of 4.6.
cat /proc/version
Linux version 3.2.0-4-rt-686-pae (debian-kernel#lists.debian.org) (gcc version 4.6.3 (Debian 4.6.3-14) ) #1 SMP PREEMPT RT Debian 3.2.65-1+deb7u2
How can I change gcc version here from 4.6 to 4.7 ?
Any help would be really helpfull for me.
Many Thanks.
As the same problem is mentioned here https://askubuntu.com/questions/193539/having-2-versions-of-gcc
I suggest you to check the solution.
This is because you have both versions installed,and 4.6 being treated as the default.
The easiest way make gcc-4.7 the default gcc is to move the symlink of /usr/bin/gcc:
sudo rm /usr/bin/gcc
sudo ln -s /usr/bin/gcc-4.7 /usr/bin/gcc
Reference link here
Is there any way to use a module in 3.2 which is compiled with kernel
3.10 ?
You can try the option -f of modprobe.

Prerequisites for gcc-4.7.2: ppl-0.11 fails to find gmp-4.3.2

I'm trying to build prerequisites for gcc-4.7.2.
Both ppl-0.11 and gmp-4.3.2 are the recommended versions in <gcc_src>/gcc-4.7.2/gcc/doc/HTML/prerequisites.html
I have built and installed gmp-4.3.2 (with --enable-cxx set)
Attempting to configure ppl-0.11 fails.
configure: error: Cannot find GMP version 4.1.3 or higher.
GMP is the GNU Multi-Precision library:
see http://www.swox.com/gmp/ for more information.
When compiling the GMP library, do not forget to enable the C++ interface:
add --enable-cxx to the configuration options.
This is my configure line:
./configure \
--prefix=$PREFIX \
--with-gmp=$PREFIX \
--with-gmp-prefix=$PREFIX \
If I look in the directory where I specified with-gmp, here is the installed gmp:
$ grep MP_VERSION $PREFIX/include/gmp*
$PREFIX/include/gmp.h:#define __GNU_MP_VERSION 4
$PREFIX/include/gmp.h:#define __GNU_MP_VERSION_MINOR 3
$PREFIX/include/gmp.h:#define __GNU_MP_VERSION_PATCHLEVEL 2
.
$ l $PREFIX/include/gmp*
$PREFIX/include/gmp.h
$PREFIX/include/gmpxx.h
.
$ l /$PREFIX/lib/libgmp*
$PREFIX/lib/libgmp.a
$PREFIX/lib/libgmp.la
$PREFIX/lib/libgmp.so -> libgmp.so.3.5.2
$PREFIX/lib/libgmp.so.3 -> libgmp.so.3.5.2
$PREFIX/lib/libgmp.so.3.5.2
$PREFIX/lib/libgmpxx.a
$PREFIX/lib/libgmpxx.la
$PREFIX/lib/libgmpxx.so -> libgmpxx.so.4.1.2
$PREFIX/lib/libgmpxx.so.4 -> libgmpxx.so.4.1.2
$PREFIX/lib/libgmpxx.so.4.1.2
Am I missing something?
As far as I can tell, GMP is available and of the requisite version
Depending on what distro you are running, have you tried to install the gmp-devel package (i.e. yum install gmp-devel on Fedora/RedHat etc)?
PPL will by default try to use default locations for GMP. If you use crosstool-ng, you must do either a cross-native or canadian-cross build. If you are doing this manually, specify CXXFLAGS to PPL's ./configure, with a -I<path-to-gmp-header> and a -Wl,-L<path-to-gmp-libs>. This allows the PPL ./configure to find the correct version of GMP.
Apparently a PPL configure with,
--prefix=$PREFIX \
--with-gmp=$PREFIX \
--with-gmp-prefix=$PREFIX \
Is not enough. I sleuthed through the ./configure script and was hacking up crosstool-ng before I realized that I was no longer building a cross-compiler, but a canadian-cross when I wasn't using my distro gcc, but another host compiler with a lower glibc shared library. This is useful if you want your compiler to run on a larger class of machines. It is unlikely that the glibc version of the build compiler will effect much.
I still had to patch 120-ppl.sh in crosstool-ng,
do_ppl_for_build() {
...
ppl_cxxflags="${CT_CFLAGS_FOR_BUILD}"
+ ppl_cxxflags+=" -I${CT_BUILDTOOLS_PREFIX_DIR}/include "
+ ppl_cxxflags+=" -Wl,-L${CT_BUILDTOOLS_PREFIX_DIR}/lib "
if [ "${CT_PPL_NEEDS_FPERMISSIVE}" = "y" ]; then
ppl_cxxflags+=" -fpermissive"
fi
So I also faced the same issue and what I did was:
1) Went inside gmp-4.3.2 folder
2) make distclean
3) ./configure --prefix=/home/sen/Documents/mingw/downloads/gmp_build --enable-cxx
4) make && make install
5) Went inside ppl-0.11 folder
6) ./configure --prefix=/home/sen/Documents/mingw/downloads/ppl_build --with-gmp-prefix=/home/sen/Documents/mingw/downloads/gmp_build --enable-cxx
7) make & make install
Took some 10-20 mins to compile and things were fine.
Thanks,
Sen
After years, the issue has been run into. The solution is firstly to download last version of gmp. Then, copy the path as in like the picture. Don't forget to ./configure with --enable-cxx, which is really important point. ./configure --enable-cxx. Now time is to ppl installation, ./configure -help indicates that --with-gmp=DIR search for libgmp/libgmpxx in DIR/include and DIR/lib. So write ./configure --with-gmp=<<dir of gmp as shown in first picture, you may have a different path>>
I wrote, respectively, ./configure --with-gmp=/usr/local/include, make, sudo make install then it works like a charm!

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