I am following
http://www.linuxfromscratch.org/blfs/view/svn/general/pcre.html
to install pcrc (OS: CentOS 6.6).
I am confused about this line
ln -sfv ../../lib/$(readlink /usr/lib/libpcre.so) /usr/lib/libpcre.so
I know it is creating a soft link but not sure why it needs readlink and why
it is ../../lib instead of /lib?
Hope it is clear. Any help appreciated.
Be careful with that.
These are generic instructions and they assume a non-CentOS/fedora distro. In CentOS/fedora, /lib is a symlink to /usr/lib (and /lib64 is a symlink to /usr/lib64). So, the instructions won't work.
On other distros, /lib and /usr/lib are distinct directories. The command is trying to create a symlink from /usr/lib to /lib, such that:
/usr/lib/libpcre.so --> /lib/libpcre.so
And, /lib/libcpre.so is the real file.
On CentOS/fedora, this would create a symlink cycle:
/usr/lib/libpcre.so --> /usr/lib/libpcre.so
Unless you have a specific reason not to, just do "yum install pcre" and let the distro install handle it. You may also want the development package: "yum install pcre-devel"
Also, note that the instructions are for a 32 bit system. If yours is 64 bit, then we're talking about /lib64 and /usr/lib64. If your system is 64 bit, but you want to create 32 bit apps, you'll need "yum install pcre.i686"
IMO, in the instructions, using "&&" is "getting cute" and makes me distrust them a bit (e.g. ./configure -blah && make) is technically correct, but it's usually better to do these as separate steps:
- ./configure -blah
- check for errors
- make
- check for errors
The reason that it's relative (using ../..) is so that you could install under /usr/local or other (e.g /usr/local/lib and /usr/local/usr/lib)
I'm starting to work with llvm infrastructure, and i'm interested in the use of the debugger tool lldb instead of default gdb. I followed the tutorial of installation of clang (Linux System, through svn options) and now wanted to know if is possible to install lldb only, instead of rebuild the whole structure of llvm. I don't found a especific documentation for that and i don't know any especific forum for llvm, so if anyone know some forum of llvm,
Sorry about my english, i'm a brazilian developer.
I actually found the solution yesterday, but was not sure how the policies to answer your own questions work here, but according to this it's allright. :)
In fact, it is quite simple.
First, you must identify the directory 'src-root' of the installation of the tools llvm/clang using the command 'llvm-config':
llvm-config --src-root
Once you find the directory, you must navigate to the path $src-root/tools and checkout the lldb:
svn co http://llvm.org/svn/llvm-project/lldb/trunk lldb
The next step is go to the build directory, if the steps of the tutorial has been followed, is just necessary to clean the build directory:
rm -rf *
Now, is the step of building the lldb, I personally have used the autoconf options (classical configure make && make install), but cmake can be used as well. When the configure script runs, the binaries of llvm and clang already installed will be detected, avoiding rebuild the whole structure of llvm/clang.
The parameters of the configure script can be changed, I use as follow because I intend to use the llvm libraries:
../llvm/configure --enable-optimized --enable-assertions --enable-shared --enable-targets=host
Then:
make -j4
sudo make install
where -j4 option is the number of threads (jobs) to be created.
Reference: http://www.felixmorgner.ch/en/blog/building-clang-lldb-and-libc-on-ubuntu/
When I tried to run an installer that uses GLEW as one of its dependencies, I got:
fatal error: GL/glew.h: No such file or directory
Downloaded glew1.10 from the official site and installed according to given instructions.
After that I got the same error again- did some research and copied glew.h to /usr/include/GL/glew.h. Ran the installer again and this time got:
/usr/bin/ld: error: cannot find -lGLEW
To my understanding this is a a common error in Linux for many projects and many libraries, probably I should copy some files from the source folder or add some path to an environment variable, what should i do?
I know that there are apt-get packages- libglew1.6-dev and libglew1.6, but its built upon glew1.6, which works but is probably out-dated for what i'm trying to build.
The automatic installer is node.js's npm, and what causes this error is trying to install node-webgl module.
Solved.
As it turned out, the installation seems to have placed the needed files inside /usr/lib64, and the linker searched for those files inside /usr/lib/ which probably is the right behavior in most cases.
Since i'm not familiar with node.js's npm (and with linking in general), my fix was as follows:
sudo cp /usr/lib64/libGLEW* /usr/lib/
sudo cp /usr/lib64/pkgconfig/* /usr/lib/pkgconfig/
Meaning, I reconstructed the same hirarchy inside the /usr/lib folder. This is probably not a best practice, but it works.
I asked IT to install Mono on CentOS using the following commands:
$yum install bison gettext glib2 freetype fontconfig libpng libpng-devel libX11 libX11-devel glib2-devel libgdi* libexif glibc-devel urw-fonts java unzip gcc gcc-c++ automake autoconf libtool make bzip2 wget
$cd /usr/local/src
$wget http://download.mono-project.com/sources/mono/mono-3.2.5.tar.bz2
$tar jxf mono-3.2.5.tar.bz2
$cd mono-3.2.5
$./configure --prefix=/opt/mono
$make && make install
However, when I run mono myapp.exe I get
-bash: mono: command not found
I know nothing about Linux - I feel like I'm in Japan. Assuming Linux has a path variable or something like it, maybe mono isn't in the path?
I can't even find an executable called mono in /usr/local/src, just a mono folder. Mind you I can't work out how to even search for a file so I might not be looking properly.
How can I tell whether its installed correctly? Maybe its just not available to the non-admin account I use?
I'm lost. Help!
If mono is properly installed, you should not get a message like -bash: mono: command not found. If something is installed then it most typically is in the $PATH.
On my system the executable is located on /usr/bin/mono (as most things are) but things may be different on a RPM-based system.
Your ./configure, however, got the prefix /opt/mono, so probably your executable also is located under that special path. (And thus mono isn't properly installed.) Why did you install it there? Anyway. If this is the fact, then you can execute it using sth like
/opt/mono/bin/mono foo.exe
to find the executable below your prefix path you could use
find /opt/mono -name mono
to see all directory entries which are named exactly mono. One of those should be your executable.
If your programm is properly installed you will usually find it's executable using "which"
which programm
like:
which firefox
/usr/bin/firefox
There are many guides and tutorials out there that recommend installing in /opt/mono in order to not conflict with the mono supplied by official distribution packages (which would be installed in /usr).
However what most of those guides miss is that /opt/mono is a non-standard prefix that will not be taken in account by the system when trying to find the executables (the system looks at the $PATH environment variable).
There are 2 possible solutions to this:
Instead of using the prefix /opt/mono use /usr/local (which is actually what ./configure or ./autogen.sh uses by default if you don't supply any prefix!). This prefix is normally included in the $PATH environment variable of most distributions.
Use your custom mono installation from a Parallel Environment. This is a bit more complicated to set up, but it's specially recommended for people who want to install two versions of mono in parallel (i.e. a very modern version, and a more stable version supplied by the official distribution packages), and have good control of when they can use one or another.
The reason that many internet tutorials recommend /opt/mono instead of /usr/local is actually because most of them are based on the wiki page (referenced above) that explains how to set up a Mono Parallel Environment, but they of course don't include the other steps to properly set up such an environment (they just borrowed the bit about how to call configure).
Program is part of the Xenomai test suite, cross-compiled from Linux PC into Linux+Xenomai ARM toolchain.
# echo $LD_LIBRARY_PATH
/lib
# ls /lib
ld-2.3.3.so libdl-2.3.3.so libpthread-0.10.so
ld-linux.so.2 libdl.so.2 libpthread.so.0
libc-2.3.3.so libgcc_s.so libpthread_rt.so
libc.so.6 libgcc_s.so.1 libstdc++.so.6
libcrypt-2.3.3.so libm-2.3.3.so libstdc++.so.6.0.9
libcrypt.so.1 libm.so.6
# ./clocktest
./clocktest: error while loading shared libraries: libpthread_rt.so.1: cannot open shared object file: No such file or directory
Is the .1 at the end part of the filename? What does that mean anyway?
Your library is a dynamic library.
You need to tell the operating system where it can locate it at runtime.
To do so,
we will need to do those easy steps:
Find where the library is placed if you don't know it.
sudo find / -name the_name_of_the_file.so
Check for the existence of the dynamic library path environment variable(LD_LIBRARY_PATH)
echo $LD_LIBRARY_PATH
If there is nothing to be displayed, add a default path value (or not if you wish to)
LD_LIBRARY_PATH=/usr/local/lib
We add the desired path, export it and try the application.
Note that the path should be the directory where the path.so.something is. So if path.so.something is in /my_library/path.so.something, it should be:
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/my_library/
export LD_LIBRARY_PATH
./my_app
Reference to source
Here are a few solutions you can try:
ldconfig
As AbiusX pointed out: If you have just now installed the library, you may simply need to run ldconfig.
sudo ldconfig
ldconfig creates the necessary links and cache to the most recent
shared libraries found in the directories specified on the command
line, in the file /etc/ld.so.conf, and in the trusted directories
(/lib and /usr/lib).
Usually your package manager will take care of this when you install a new library, but not always, and it won't hurt to run ldconfig even if that is not your issue.
Dev package or wrong version
If that doesn't work, I would also check out Paul's suggestion and look for a "-dev" version of the library. Many libraries are split into dev and non-dev packages. You can use this command to look for it:
apt-cache search <libraryname>
This can also help if you simply have the wrong version of the library installed. Some libraries are published in different versions simultaneously, for example, Python.
Library location
If you are sure that the right package is installed, and ldconfig didn't find it, it may just be in a nonstandard directory. By default, ldconfig looks in /lib, /usr/lib, and directories listed in /etc/ld.so.conf and $LD_LIBRARY_PATH. If your library is somewhere else, you can either add the directory on its own line in /etc/ld.so.conf, append the library's path to $LD_LIBRARY_PATH, or move the library into /usr/lib. Then run ldconfig.
To find out where the library is, try this:
sudo find / -iname *libraryname*.so*
(Replace libraryname with the name of your library)
If you go the $LD_LIBRARY_PATH route, you'll want to put that into your ~/.bashrc file so it will run every time you log in:
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/path/to/library
Update
While what I write below is true as a general answer about shared libraries, I think the most frequent cause of these sorts of message is because you've installed a package, but not installed the -dev version of that package.
Well, it's not lying - there is no libpthread_rt.so.1 in that listing. You probably need to re-configure and re-build it so that it depends on the library you have, or install whatever provides libpthread_rt.so.1.
Generally, the numbers after the .so are version numbers, and you'll often find that they are symlinks to each other, so if you have version 1.1 of libfoo.so, you'll have a real file libfoo.so.1.0, and symlinks foo.so and foo.so.1 pointing to the libfoo.so.1.0. And if you install version 1.1 without removing the other one, you'll have a libfoo.so.1.1, and libfoo.so.1 and libfoo.so will now point to the new one, but any code that requires that exact version can use the libfoo.so.1.0 file. Code that just relies on the version 1 API, but doesn't care if it's 1.0 or 1.1 will specify libfoo.so.1. As orip pointed out in the comments, this is explained well at here.
In your case, you might get away with symlinking libpthread_rt.so.1 to libpthread_rt.so. No guarantees that it won't break your code and eat your TV dinners, though.
You need to ensure that you specify the library path during
linking when you compile your .c file:
gcc -I/usr/local/include xxx.c -o xxx -L/usr/local/lib -Wl,-R/usr/local/lib
The -Wl,-R part tells the resulting binary to also look for the library
in /usr/local/lib at runtime before trying to use the one in /usr/lib/.
Try adding LD_LIBRARY_PATH, which indicates search paths, to your ~/.bashrc file
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/path_to_your_library
It works!
The linux.org reference page explains the mechanics, but doesn't explain any of the motivation behind it :-(
For that, see Sun Linker and Libraries Guide
In addition, note that "external versioning" is largely obsolete on Linux, because symbol versioning (a GNU extension) allows you to have multiple incompatible versions of the same function to be present in a single library. This extension allowed glibc to have the same external version: libc.so.6 for the last 10 years.
cd /home/<user_name>/
sudo vi .bash_profile
add these lines at the end
LD_LIBRARY_PATH=/usr/local/lib:<any other paths you want>
export LD_LIBRARY_PATH
Another possible solution depending on your situation.
If you know that libpthread_rt.so.1 is the same as libpthread_rt.so then you can create a symlink by:
ln -s /lib/libpthread_rt.so /lib/libpthread_rt.so.1
Then ls -l /lib should now show the symlink and what it points to.
I had a similar error and it didn't fix with giving LD_LIBRARY_PATH in ~/.bashrc .
What solved my issue is by adding .conf file and loading it.
Go to terminal an be in su.
gedit /etc/ld.so.conf.d/myapp.conf
Add your library path in this file and save.(eg: /usr/local/lib).
You must run the following command to activate path:
ldconfig
Verify Your New Library Path:
ldconfig -v | less
If this shows your library files, then you are good to go.
running:
sudo ldconfig
was enough to fix my issue.
I had this error when running my application with Eclipse CDT on Linux x86.
To fix this:
In Eclipse:
Run as -> Run configurations -> Environment
Set the path
LD_LIBRARY_PATH=/my_lib_directory_path
Wanted to add, if your libraries are in a non standard path, run ldconfig followed by the path.
For instance I had to run:
sudo ldconfig /opt/intel/oneapi/mkl/2021.2.0/lib/intel64
to make R compile against Intel MKL
All I had to do was run:
sudo apt-get install libfontconfig1
I was in the folder located at /usr/lib/x86_64-linux-gnu and it worked perfectly.
Try to install lib32z1:
sudo apt-get install lib32z1
If you are running your application on Microsoft Windows, the path to dynamic libraries (.dll) need to be defined in the PATH environment variable.
If you are running your application on UNIX, the path to your dynamic libraries (.so) need to be defined in the LD_LIBRARY_PATH environment variable.
The error occurs as the system cannot refer to the library file mentioned. Take the following steps:
Running locate libpthread_rt.so.1 will list the path of all the files with that name. Let's suppose a path is /home/user/loc.
Copy the path and run cd home/USERNAME. Replace USERNAME with the name of the current active user with which you want to run the file.
Run vi .bash_profile and at the end of the LD_LIBRARY_PATH parameter, just before ., add the line /lib://home/usr/loc:.. Save the file.
Close terminal and restart the application. It should run.
I got this error and I think its the same reason of yours
error while loading shared libraries: libnw.so: cannot open shared
object file: No such file or directory
Try this. Fix permissions on files:
cd /opt/Popcorn (or wherever it is)
chmod -R 555 * (755 if not ok)
I use Ubuntu 18.04
Installing the corresponding -dev package worked for me,
sudo apt install libgconf2-dev
Before installing the above package, I was getting the below error:
turtl: error while loading shared libraries: libgconf-2.so.4: cannot open shared object file: No such file or directory
I got this error and I think its the same reason of yours
error while loading shared libraries: libnw.so: cannot open shared object
file: No such file or directory
Try this. Fix permissions on files:
sudo su
cd /opt/Popcorn (or wherever it is)
chmod -R 555 * (755 if not ok)
chown -R root:root *
A similar problem can be found here.
I've tried the mentioned solution and it actually works.
The solutions in the previous questions may work. But the following is an easy way to fix it.
It works by reinstalling the package libwbclient
in fedora:
dnf reinstall libwbclient
You can read about libraries here:
https://domiyanyue.medium.com/c-development-tutorial-4-static-and-dynamic-libraries-7b537656163e