Can I avoid exporting LD_LIBRARY_PATH by hardcoding library paths in the executable? - linux

I'm zipping a pre-built (no source/object files) binary application for distribution. The binary application requires a couple of libraries not included by default. The only way I seem to be able to get the application to start on the end-user is by including a run.sh that sets the library path to the current directory:
export LD_LIBRARY_PATH=./:$LD_LIBRARY_PATH
./MyApp.out
However, I'd really like to allow the user to just unzip the zip and doubleclick MyApp.out (without the shell script). Can I edit MyApp.out to search the current directory for the library? I've done something similar on OSX using install_name_tool, but that tool isn't available here.

You want to set the rpath. See this answer. So link using
gcc yourobjects*.o -L/some/lib/dir/ -lsome -Wl,-rpath,.
But you might want even to use -Wl,-rpath,$PWD or perhaps -Wl,-rpath,'$ORIGIN'. See this.
You could also (and this should work for a pre-built executable) configure your /etc/ld.so.conf by adding a line there with an absolute path (of the directory containing the lib), then running ldconfig -v ... See ldconfig(8)
I would suggest adding /usr/local/lib into /etc/ld.so.conf and making a symlink from /usr/local/lib/libfoo.so to e.g. $HOME/libfoo.so etc... (then run ldconfig ...). I don't think adding a user specific directory to /etc/ld.so.conf is reasonable ...
PS. What you really want is to package your application (e.g. as a *.deb package for Debian or Ubuntu, or an *.rpm for Fedora or Redhat). Package management systems handle dependencies!

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Add software bin or just add soft link for executable file in bin when install software on linux?

I’m not root for the linux server,
so I choose to install softwares in my $HOME/local/bin, I already added the $HOME/local/bin directory to the PATH environment variable, wrote in my .bashrc.
Some softwares install this way like:
tar xvzf ncurses-5.9.tar.gz
cd ncurses-5.9
./configure --prefix=$HOME/local
make
make install
cd ..
So it will directly install in my $HOME/local/bin.
But for some softwares, after download like sbt-1.2.1.zip (based on java), and decompression, shows just a file fold sbt, it contains three foldsbin conf lib, and in its bin, contains one executable file named sbt and java9-rt-export.jar sbt-launch-lib.bash sbt-launch.jar sbt.bat.
Here I wonder:
I should just soft link this executable sbt file path under my $HOME/local/bin, then source my .bashrc?
Or, after decompression, add one line in my .bashrc export PATH="downloadpath/sbt/bin:$PATH"?
Since just one executable downloadpath/sbt/bin, so I'm not sure it is right to add whole bin fold path, if software's bin fold contains executable files (one or many), I think this situation is more convenient for just add it's bin in .bashrc, but even so, I'm not sure its right?
I'm not familiar with installation software, now I usually know way
but not why. Here I shows two ways (more ways not be showed here) to
install, executable file always be written in bin or src? But some
softwares no bin just src but no executable files in it...
Slurm also can use modules to install software, conda also other way, but I want to
confirm these traditional ways I mentioned (that two) still can be
used on slurm or conda?
However, any suggestion even one aspect's reminding will be grateful!
For precompiled software, or, in general, software that does not offer configure scripts or (C)make files, it is ofter better to leave them in their target directory and adapt the *PATH (PATH to binaries, but also LD_LIBRARY_PATH, LIBRARY_PATH to libraries and CPATH to include files and MANPATH to the man page) environment variables.
The reason is that the software might be configured to read files with hardcoded paths, relative to the position of the executable, such as libraries, etc.
In your case, you might also need to setup the CLASSPATH env variable to the directory with the jar files.
To ease software installation, you can use tools such as easybuild that can help, and even create user modules just like the system module installed by the system administrators.
There is something wrong in my opinion with your setup. If you don`t have root account on your server, is not better to test what you have to test, in a more safe environment - for example a vm/container on your developement machine ?
However, in your situation maybe it can be better to start sbt by using a separate bash script than modifying your .bashrc

How to manage development and installed versions of a shared library?

In short: This question is basically about telling Linux to load the development version of the .so file for executables in the dev directory and the installed .so file for others.
In long: Imagine a shared library, let's call it libasdf.so. And imagine the following directories:
/home/user/asdf/lib: libasdf.so
/home/user/asdf/test: ... perform_test
/opt/asdf/lib: libasdf.so
/home/user/jkl: ... use_asdf
In other words, you have a development directory for your library (/home/user/asdf) and you have an installed copy of its previous stable version (/opt/asdf) and some other programs using it (/home/user/jkl).
My question is, how can I tell Linux, to load /home/user/asdf/lib/libasdf.so when executing /home/user/asdf/test/perform_test and to load /opt/asdf/lib/libasdf.so when executing /home/user/jkl/use_asdf? Note that, even though I specify the directory by -L during link, Linux uses other methods (for example /ect/ld.so.conf and $LD_LIBRARY_PATH) to find the .so file.
The reason I need such a thing is that, of course the executables in the development directory need to link with the latest version of the library, while the other programs, would want to use the stable version.
Putting ../lib in the library path doesn't seem like a secure idea, not to mention not completely correct since you can't run the test from a different directory.
One solution I thought about is to have perform_test link with libasdf-dev.so and upon install, copy libasdf-dev.so as libasdf.so and have others link with that. This solution has one problem though. Imagine the following additional directory:
/home/user/asdf/tool: ... use_asdf_too
Which gets installed to:
/opt/asdf/bin: use_asdf_too
In my solution, it is unknown what use_asdf_too should be linked against. If linked against libasdf.so, it wouldn't work properly if invoked from the dev directory and if linked against libasdf-dev.so, it wouldn't work properly if invoked from the installed location.
What can I do? How is this managed by other people?
Installed shared objects usually don't just end with ".so". Usually they also include their soname, such as libadsf.so.42.1. The .so file for development is typically a symlink to a fully-versioned filename. The linker will look for the .so file and resolve it to the full filename, and the loader will then load the fully-versioned library instead.

Installation and maintenance of multiple versions of OpenCV (applicable to any other 3rd party library as well)

I have been trying to do build and use OpenCV 2.3.0 on my Fedora15 Lovelock 64bit machine.
Background:
First, on my 64bit Fedora15, OpenCV2.2.0 seems to be in the locations namely
/usr/share/opencv
/usr/doc
/usr/lib64 &
/usr/bin
I do not find the include files though (in /usr/include). This means that the development package was n t installed. My package manager does not list the development packages when i try to Add/remove software.
I have a need to create applications, some of which just link to 2.2 and others which link to 2.3.O of the OpenCV library.So, I thought the best solution would be to have a separate location for 3rd party libraries that i use for my development . So I created a directory in /local named soft and created an OpenCV directory. A directory structure like this one.
/local/soft/
OpenCV/
OpenCV2.2.0/
source-files
build
OpenCV2.3.0/
source-files
build
installation
share/opencv
doc
include
lib
Now, i tried building OpenCV2.3.0 and i succeeded. I configure CMake to use CMAKE_INSTALL_PREFIX to the directory named "installation" (see above), instead of the default /usr/local/. Clean. huh?
I tried building and installing OpenCv 2.2.0 in the same way. Alas 2.2.0 complains something during the build. So i thought i ll link to the already existing version in the standard locations. BUT, when i try to install the dev packages for 2.2 using my package manager,the development files for x86_64 are not found :-) which means i dont have the headers to link to the libraries in the standard location.
I cant build my executable since linker ld would not find the OpenCV that i have installed in the non-standard location.(although i point it to the exact location using the -L and -l options with gcc in my Eclipse).
Question 1: Am i doing the right thing in maintaining installations in non-standard locations? Is /usr/ the standard location where the package manager will always do the installation?
Question2 : What is the right way of linking to these libraries installed in non-standard locations? Why would not ld recognize my .so files in the lib folder?
sudo g++ logpolar.cpp -o logpolar.o -I /local/soft/OpenCV/opencv2.3.1/installation/include/ -l/local/soft/OpenCV/opencv2.3.1/build/lib/libopencv_core.so
But ld canot find -l/local/soft/OpenCV/opencv2.3.1/build/lib/libopencv_core.so
I checked the lib folder and there sure is a beautiful symbolic link to libopencv_core.so.2.3
The standard approach is to use /usr/local directory structure that already has predefined paths like /usr/local/bin, /usr/local/sbin, /usr/local/include, /usr/local/lib.
You put your software here and everything will JustWork(TM). Every Linux distro (incl. Fedora) is set up so it will load programs (libraries, headers) from this libraries.
If you would use GNU toolchain (autoconf, automake => autotools) you would be fine. With CMake you probably need to setup paths for /usr/local/include and /usr/local/lib.
On the other hand this approach wont let you use multiple versions. You can only have one. The one in /usr/local overrides the system one (installed in /usr/bin) because these paths goes first.
You can keep your approach, it is nothing incorrect. We usually put such a software in the /opt folder, so you would go for /opt/opencv/X.Y where X.Y are the version numbers.
Q2: Read the gcc man page and search for the -L option. You need something like:
gcc ... -I/opt/opencv/2.0/include -lsystem_lib -L/opt/opencv/2.0/lib -lopencv ... ...
Do not forget to set LD_LIBRARY_PATH when running programs in multiple versions to properly load correct version:
LD_LIBRARY_PATH=/opt/opencv/2.0/lib /opt/opencv/2.0/bin/opencv

What's the accepted method for deploying a linux application that relies on shared libraries?

I have an application that relies on Qt, GDCM, and VTK, with the main build environment being Qt. All of these libraries are cross-platform and compile on Windows, Mac, and Linux. I need to deploy the application to Linux after deploying on Windows. The versions of vtk and gdcm I'm using are trunk versions from git (about a month old), more recent than what I can get apt-get on Ubuntu 11.04, which is my current (and only) Linux deployment target.
What is the accepted method for deploying an application that relies on these kinds of libraries?
Should I be statically linking here, to avoid LD_LIBRARY_PATH? I see conflicting reports on LD_LIBRARY_PATH; tutorials like this one suggest that it's the 'right way' to modify the library path to use shared libraries through system reboots. Others suggest that I should never set LD_LIBRARY_PATH. In the default version of GDCM, the installation already puts libraries into the /usr/local/lib directory, so those libraries get seen when I run ldd <my program>. VTK, on the other hand, puts its libraries into /usr/local/lib/vtk-5.9, which is not part of the LD_LIBRARY_PATH on most user's machines, and so is not found unless some change is made to the system. Copying the VTK files into '/usr/local/lib' does not allow 'ldd' to see the files.
So, how can I make my application see VTK to use the libraries?
On windows, deploying the dlls is very straightforward, because I can just include them in the installer, and the application finds them because they are in the local directory. That approach does not work in Linux, so I was going to have the users install Qt, GDCM, and VTK from whatever appropriate source and use the default locations, and then have the application point to those default locations. However, since VTK is putting things into a non-standard location, should I also expect users to modify LD_LIBRARY_PATH? Should I include the specific versions of the libraries that I want and then figure out how to make the executable look in the local directory for those libraries and ignore the ones it finds in the library path?
Every "serious" commercial application I have ever seen uses LD_LIBRARY_PATH. They invariably include a shell script that looks something like this:
#!/bin/sh
here="${0%/*}" # or you can use `dirname "$0"`
LD_LIBRARY_PATH="$here"/lib:"$LD_LIBRARY_PATH"
export LD_LIBRARY_PATH
exec "$0".bin "$#"
They name this script something like .wrapper and create a directory tree that looks like this:
.wrapper
lib/ (directory full of .so files)
app1 -> .wrapper (symlink)
app1.bin (executable)
app2 -> .wrapper (symlink)
app2.bin (executable)
Now you can copy this whole tree to wherever you want, and you can run "/path/to/tree/app1" or "/path/to/tree/app2 --with --some --arguments" and it will work. So will putting /path/to/tree in your PATH.
Incidentally, this is also how Firefox and Chrome do it, more or less.
Whoever told you not to use LD_LIBRARY_PATH is full of it, IMHO.
Which system libraries you want to put in lib depends on which Linux versions you want to officially support.
Do not even think about static linking. The glibc developers do not like it, they do not care about supporting it, and they somehow manage to break it a little harder with every release.
Good luck.
In general, you're best off depending on the 'normal' versions of the libraries for whatever distribution you're targetting (and saying you don't support dists that don't support recent enough versions of the lib), but if you REALLY need to depend on a bleeding edge version of some shared lib, you can link your app with -Wl,-rpath,'$ORIGIN' and then install a copy of the exact version you want in the same directory as your executable.
Note that if you use make, you'll need $$ in the makefile to get a single $ into the argument that is actually sent to the linker. The single qutoes are needed so the shell doesn't munge things...
Well, there are two options for deploying Linux application.
The correct way:
make a package for your app and for the libraries, if they are so special, that they can't be installed from standard repositories
There are two major package formats. RPM and DEB.
The easy way:
make a self-extract file that will install the "windows way" into /opt.
You can have libraries in the same directory as the executable, it's just not the preferred way.

How to link shared libraries in local directory, OSX vs Linux

I have some shared/dynamic libraries installed in a sandbox directory. I'm building some applications which link agains the libraries. I'm running into what appears to be a difference between OSX and Linux in this regard and I'm not sure what the (best) solution is.
On OSX the location of library itself is recorded into the library, so that if your applications links against it, the executable knows where to look for the library at runtime. This works like expected with my sandbox, because the executable looks there instead of system wide install paths.
On Linux I can't get this to work. Apparently the library location is not present in the library itself. As I understand it you have to add the folders which contain libraries to /etc/ld.so.conf and regenerate the ld cache by running ldconfig.
This doesn't seem to do the trick for me because my libraries are located inside a users home directory. It looks like ldconfig doesn't like that, which makes sense actually.
How can I solve this? I don't want to move the libraries out of my sandbox.
On Linux, run your program with the environment variable LD_LIBRARY_PATH set to your sandbox dir.
(I remember having used a flag -R to include library paths in the binary, but either it has been removed from gcc or it was only available on BSD systems.)
On Linux you should set LD_RUN_PATH to your sandbox dir. This is better than setting LD_LIBRARY_PATH because you're telling the linker where the library is at link time, rather than telling the shared library loader at run time.
See: Link

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