I have a Haskell script that runs via a shebang line making use of the runhaskell utility. E.g...
#! /usr/bin/env runhaskell
module Main where
main = do { ... }
Now, I'd like to be able to determine the directory in which that script resides from within the script, itself. So, if the script lives in /home/me/my-haskell-app/script.hs, I should be able to run it from anywhere, using a relative or absolute path, and it should know it's located in the /home/me/my-haskell-app/ directory.
I thought the functionality available in the System.Environment module might be able to help, but it fell a little short. getProgName did not seem to provide useful file-path information. I found that the environment variable _ (that's an underscore) would sometimes contain the path to the script, as it was invoked; however, as soon as the script is invoked via some other program or parent script, that environment variable seems to lose its value (and I am needing to invoke my Haskell script from another, parent application).
Also useful-to-know would be whether I can determine the directory in which a pre-compiled Haskell executable lives, using the same technique or otherwise.
As I understand it, this is historically tricky in *nix. There are libraries for some languages to provide this behavior, including FindBin for Haskell:
http://hackage.haskell.org/package/FindBin
I'm not sure what this will report with a script though. Probably the location of the binary that runhaskell compiled just prior to executing it.
Also, for compiled Haskell projects, the Cabal build system provides data-dir and data-files and the corresponding generated Paths_<yourproject>.hs for locating installed files for your project at runtime.
http://www.haskell.org/cabal/release/cabal-latest/doc/users-guide/authors.html#paths-module
There is a FindBin package which seems to suit your needs and it also works for compiled programs.
For compiled executables, In GHC 7.6 or later you can use System.Environment.getExecutablePath.
getExecutablePath :: IO FilePathSource
Returns the absolute pathname of the current executable.
Note that for scripts and interactive sessions, this is the path to the
interpreter (e.g. ghci.)
There is executable-path which worked with my runghc script. FindBin didn't work for me as it returned my current directory instead of the script dir.
I could not find a way to determine script path from Haskell (which is a real pity IMHO). However, as a workaround, you can wrap your Haskell script inside a shell script:
#!/bin/sh
SCRIPT_DIR=`dirname $0`
runhaskell <<EOF
main = putStrLn "My script is in \"$SCRIPT_DIR\""
EOF
Related
Well the idea goes as followed,
I have a bash file for linux, there I obviously run it by making ./my_run.
The problem is I'm in windows so I downloaded and installed cygwin.
I added cygwin bin to the Enviromental Variables and check that at least "ls" works so I guessed I did it well.
When I try to run it with the cmd it displays:
'.' is not recognized as an internal or external command,
operable program or batch file.
As if the cygwin variables were not correctly installed (as I said I tried ls and works).
Then I tried it directly with cygwin and when doing the ./my_run I got it to work right.
So how is that I can use some commands like ls but when doing ./ it doesn't work on the cmd? How can I fix this?
Well, cygwin is only a shared library and a lot of stuff (the programs) using it (read Cygwin doc). cygwin.dll changes internally path resolution / chars to allow you to say ./my_script and converts it to .\my_script before doing the actual windows call, it also adds the proper extension to executables to allow it to execute windows binaries. This magic persists as long as you use it. cmd.exe is a Microsoft Windows command shell that is completely unaware of Cygwin's shared library and by that reason it doesn't use it, so it will not call it for path translation, even if you populate the environment of zetabytes of stuff. When you run in Cygwin terminal, you are running bash shell, which is a Cygwin executable, linked to cygwin.dll. It manages to use Cygwin library for all the unix system call emulations, so when you pass it e.g. to exec("./my_script", ...);, it internally converts that to try for ./my_script, then .\my_script, ./my_script.exe, ... and the same for .com and .bat extensions.
This fact often makes some people to say that Cygwin is not a good, efficient, environment. But the purpose was not to be efficient (and it is, as it caches entries and makes things best to be efficient) but to be compatible.
In your example ls is a Cygwin executable that mimics the /bin/ls executable from unix systems. It uses the Cygwin library, so all path resolution will be properly made (well, under some constraints, as you'll see after some testing) and everything will work fine. But you cannot pretend all your Windows applications to suddenly transform themselves and begin working as if they where in a different environment. This requires some try and error approach that you have to try yourself. And read Cygwin documentation, it is very good and covers everything I've said here.
If you open up Cygwin and run the command there you should be fine.
It seems this question has been asked very often before but none of the solutions seem to apply in my case.
I'm in a CMake/Linux environment and have to run an executable binary during the build step (protoc in particular).
This binary needs a library but it's not installed (and cannot be) in the in the standard directories like /usr, so the library cannot be found.
Unfortunately I cannot manipulate the protoc call because it's embedded in a 3rd party script.
I can now set LD_LIBRARY_PATH before every make or set it system wide but this is very inconvenient especially when it comes to IDEs in which the build takes place or distributed build scenarios with continuous build environments.
I tried to set LD_LIBRARY_PATH via
set(ENV{LD_LIBRARY_PATH} "/path/to/library/dir")
but this seems to have no effect during the build step.
So my question is: can I set a library search path in CMake which is used during the build?
Try this
SET(ENV{LD_LIBRARY_PATH} "/path/to/library/dir:$ENV{LD_LIBRARY_PATH}")
I also used this dirty trick to temporary change some environment variables:
LD_LIBRARY_PATH="/path/to/library/dir:$LD_LIBRARY_PATH" cmake ...
After execution of this line LD_LIBRARY_PATH is not changed in the current shell.
Also, I do not find it bad to change LD_LIBRARY_PATH before invoking cmake:
export LD_LIBRARY_PATH=...
It won't change anything system-wide, but it would be used for your current shell, current build process. The same holds for CI builds. You can save the variable and restore it after cmake invocation:
MY_LD=$LD_LIBRARY_PATH
export LD_LIBRARY_PATH=...
cmake...
export LD_LIBRARY_PATH=$MY_LD
I have recently run into a somewhat similar problem.
My solution was to incorporate sourcing a file that set the appropriate environment into every command.
For example, this custom command:
add_custom_command(
OUTPUT some_output
COMMAND some_command
ARGS some_args
DEPENDS some_dependencies
COMMENT "Running some_command some_args to produce some_output"
)
Would become:
set(my_some_command_with_environment "source my_environment_script.sh && some_command")
add_custom_command(
OUTPUT some_output
COMMAND bash
ARGS -c "${my_some_command_with_environment} some_args"
DEPENDS some_dependencies
COMMENT "Running some_command some_args to produce some_output"
VERBATIM
)
Obviously, this has some disadvantages:
It relies on a bash shell being available.
It sources the environment script for every command invocation (performance issue) and you will have to change all invocations of commands that rely on that environment variables.
It changes the normal syntax of having the command follow COMMAND and the arguments follow ARGS, as now the 'real' command is part of the ARGS.
My CMake-Fu has proven insufficient to find a syntactically nicer way of doing this, but maybe somebody can comment a nicer way.
I had a similar issue for an executable provided by a third party library. The binary was linked against a library not provided by the distribution but the required library was included in the libs directory of the third party library.
So running LD_LIBRARY_PATH=/path/to/thirdparty/lib /path/to/thirdparty/bin/executable worked. But the package config script didn't set up the executable to search /path/to/thirdparty/lib for the runtime dependent so CMake would complain when CMake tried to run the executable.
I got around this by configuring a bootstrap script and replacing the IMPORTED_LOCATION property with the configured bootstrapping script.
_thirdpartyExe.in
#!/bin/bash
LD_LIBRARY_PATH=#_thirdpartyLibs# #_thirdpartyExe_LOCATION# "$#"
CMakeLists.txt
find_package(ThirdPartyLib)
get_target_property(_component ThirdPartyLib::component LOCATION)
get_filename_component(_thirdpartyLibs ${_component} DIRECTORY)
get_target_property(_thirdpartyExe_LOCATION ThirdPartyLib::exe IMPORTED_LOCATION)
configure_file(
${CMAKE_CURRENT_LIST_DIR} _thirdpartyExe.in
${CMAKE_BINARY_DIR}/thirdpartyExeWrapper #ONLY
)
set_target_properties(ThirdPartyLib::exe PROPERTIES IMPORTED_LOCATION ${CMAKE_BINARY_DIR}/thirdpartyExeWrapper)
Honestly I view this as a hack and temporary stop gap until I fix the third party library itself. But as far as I've tried this seems to work on all the IDE's I've thrown at it, Eclipse, VSCode, Ninja, QtCreator, ... etc
I have a script file that I was given to run in windows using Cygwin. When I try to use this file I get the following error
-bash: /sigdet/filename: cannot execute binary file: Exec format error.
sigdet is the folder within the Cygwin directory that I have the script. Rawdata is the name of the directory with the raw data files that the script is supposed to analyze.
To try and solve this, I have changed the file permissions, I have checked to make sure that it is on a 64 bit machine and the script appears to have compiled on a 64-bit machine. After these steps, I don't know what else the problem could be. Here are the commands I've entered:
I first changed the directory like so:
$ cd /sigdet/
Then I ran the script that is suppsed to work:
$ /sigdet/filename -i rawdata
Does the script file need to have an extension in windows? I've tried changing it to a .sh extension with no luck. I'm told that it just works on other windows machines just how it is.
Thanks to anyone that can help with this.
Your file is not an executable. It most probably contains ELF executable which is designed for Linux operating system, or it's corrupt.
If your file was a shell script, or in fact anything that contained plain text, you'd get different errors (such as, "expected command name" or "unknown command: XYZ" etc.)
Scripts are not supposed to have file extensions, like any executables. On the other hand, they should have shebangs: small text located in the first line that tells the system the path to the interpreter. For example, a Python executable script might be named whatever and have #!/usr/bin/python3 or similar in the first line. When you run it through ./whatever in the shell, it'll look for python3 in /usr/bin and run your file like this: /usr/bin/python3 ./whatever. (In fact, thanks to this you can also specify additional parameters that get passed to the interpreter.)
There is also a chance that your script is valid, but it contains a shebang pointing to bad interpreter. If that is the case, then most likely the path is correct, otherwise you'd get /whatever/interpreter: bad interpreter: no such file or directory error or similar. But then, all the other points apply to the interpreter (which is just another executable...)
If the script and/or interpreter was meant to be executed on Windows or Cygwin at least, it should either contain aforementioned shebang (#!/path in the first name) or it should be Windows executable (in which case the file data should begin with MZ letters, you can inspect it in notepad.) If it isn't, it means the files you were given can't run on Cygwin.
Had this same problem. Added the following at the top of makefile:
export ARCH = CYGNUS
What happened during the make process is that Linux and Windows versions of the executables were created. You just have to use ./.exe versions.
In my case, I got the error when I used a wrong command to compile my C program. When I used the right command:
gcc myprog.c -o myprog.exe
the error was resolved.
I am trying to learn haskell using haskell koans https://github.com/HaskVan/HaskellKoans. The installation instructions found is not working and they look presumably for linux. I need help to get the koans working on windows.
If you look at the top of setup-koans, you'll see:
#!/usr/bin/env runhaskell
import Control.Monad (unless)
...etc
That first line with the hashbang indicates that a unix shell running this file as a program should pass everything that follows (the haskell source file, in this case) to the command specified (/usr/bin/env runhaskell in this case).
If you have a GHC installation, and runghc in your path, you should be able to remove that line and do runghc setup-koans.
You might also like to play with cygwin, or with a linux virtual machine (e.g. in docker) to familiarize yourself with this sort of thing.
I am extremely new to haskell and I have been searching all over the web but I haven't been able to solve my problem. I downloaded the Quipper package but I have not been able to get haskell to recognize where all of the modules and files are and how to properly link everything.
I have downloaded all of the files and programs and installed them properly, I just dont know how to get haskell to recognize the quipper libraries and templates. Evey time I try:
:load And_gate.hs or some other file.
I get:
Could not find module "Quipper" or its respective modules it requires.
I don't think it is an error or anything, I think it is just my lack of knowledge on how haskell works.
I'm using windows 7.
So I emailed Peter Selinger, one of the professors who created Quipper.
The only thing I need to do extra was inside MSYS:
ghci -iC:/quipper -iC:/quipper/quipper
This complies everything correctly and the files run properly.
Here is his email to me:
Dear -----,
thanks for writing. Let me see if I can help.
Are you following the instructions in the README file? Under "Building
the various algorithms and programs", the instruction is to run
"make". This would build all of the tests in the "tests" directory
automatically.
Next, to compile a Quipper program, you should use the "quipper"
script that is located in quipper/scripts. It works just like "ghc",
except that it automatically includes the correct directories for
Quipper's files in the search path. On Windows, you would be using
"quipper.bat".
Quipper is not really meant to be run interactively, i.e., from ghci.
However, if you do need to run Quipper interactively, I recommend
using the "quipperi" script, also in quipper/scripts. This too would
set the load paths correctly. In Windows, use "quipperi.bat".
Finally, if you need to include Quipper stuff from ghci, but for some
reason can't or don't want to use the quipperi script, you need to
specify those directories with the "-i" option, for example
ghci -iC:/quipper -iC:/quipper/quipper
It could be that in Windows, you need to use "\" instead of "/", but I
am not sure if this is necessary.
I hope this helps, -- Peter
When compiling and exe with ghc just make sure you include the commands:
-iC:/quipper -iC:/quipper/quipper.
If you use the quipper script as suggested by Professor Selinger, inside of MSYS do the following:
Navigate to the folder in which all of the Quipper files are held, this was my case:
cd C:/quipper/quipper/scripts
Then type quipper and your file's location in MSYS to compile an exe like so:
quipper C:/quipper/tests/And_gate.hs
The file will compile and should print updates like so:
[1 of 22] Compiling Libraries.Typeable (......
[2 of 22] Compiling Libraries.Tuple (......
and so on.
The exe (in this case And_gate.exe) will be inside the folder it was compiled from (C:/quipper/tests). You'll need to move it to a folder that contains the acroread.bat which comes in quipper/scripts for it to work properly.
For some reason, this code isn't packaged as a standard Haskell package. It if were, installing it would be fairly simple. As it is, the instructions in the README file look awful (especially under Windows, where it looks like you need MSYS to run the makefile).
Your problem might be as simple as telling GHCi which folder to look in to find the files; you can do that using the :cd command. Since you're on Windows, I'd suggest trying WinGHCi, which should allow you to browse to the right folder using the GUI.
If it isn't that simple... really, as a Haskell beginner, you're probably going to struggle to get this working. The documentation looks pretty minimal.
If you red both README and INSTALLING.windows and did everything as well, then you should add a path to Quipper's script folder to environment variable. Here is the path:
quipper-*/quipper/scripts/
where quipper-* is a <distribution name>-<version>.
There are two important scripts in that folder. The first one is quipper.bat which runs a ghc compiler to run Quipper's modules. The second one is quipperi.bat which is a ghci analogue for Quipper.
Now, when you added a path to variable, you can run And_gate.hs in Quipper's interpreter as follows:
quipperi And_gate.hs