# Ruby one-file launcher that sets up environment? **URL:** \ **Category:** Ruby\ **Created:** [May 23, 2010, 1:29pm UTC](https://www.ruby-forum.com/t/ruby-one-file-launcher-that-sets-up-environment/189054 "2010-05-23T13:29:40Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Michal\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/779978/32.png) [@Michal\_S](https://www.ruby-forum.com/u/Michal_S)\ **Post date:** [May 23, 2010, 1:29pm UTC](https://www.ruby-forum.com/t/ruby-one-file-launcher-that-sets-up-environment/189054/1 "2010-05-23T13:29:40Z")
Hello I am trying to run some JRuby script and I have to set the CLASSPATH for my script to work. I use a launcher locally so I can run the script as ./scripts/mylauncher script.rb but if I wanted to distribute a sample script this is somewhat troublesome. I tried to embed the ruby code in a shell script but as Ruby refuses to read the code from stdin this is not quite nice: #!/bin/sh CLASSPATH= jruby -e ’ ’ “$@” Note that while this example uses JRuby there might be native extensions which require specific environment settings and woud have the same launcher requirements. If somebody had a better idea for a launcher it would be nice. Thanks Michal ---
**Author:** ![Michal\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/779978/32.png) [@Michal\_S](https://www.ruby-forum.com/u/Michal_S)\ **Post date:** [May 23, 2010, 1:55pm UTC](https://www.ruby-forum.com/t/ruby-one-file-launcher-that-sets-up-environment/189054/2 "2010-05-23T13:55:25Z")
Michal S. wrote: > I am trying to run some JRuby script and I have to set the CLASSPATH > for my script to work. > […] > Note that while this example uses JRuby there might be native > extensions which require specific environment settings and woud have > the same launcher requirements. To rephrase: Your software requires some environment variables to be set in order to run. The standard way of providing this is is to install a script with the executable bit set in /etc/profile.d/ that modifies the environment variables on login, e.g.: /etc/profile.d/mypackage.sh: export CLASSPATH="$CLASSPATH:/additional/class/paths" /etc/profile is read on login and should run any executable scripts it finds in /etc/profile.d/. Hope this helps, Henning ---
**Author:** ![Michal\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/779978/32.png) [@Michal\_S](https://www.ruby-forum.com/u/Michal_S)\ **Post date:** [May 24, 2010, 12:19am UTC](https://www.ruby-forum.com/t/ruby-one-file-launcher-that-sets-up-environment/189054/3 "2010-05-24T00:19:58Z")
On 23 May 2010 13:55, Henning B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > in order to run. The standard way of providing this is is to install a > Hope this helps, > Henning Well, actually it does not. If I wanted to distribute the script in multiple files then distributing it with a launcher would be just fine and would not require the user of the script to have administrative privileges to install the script in a system directory nor the additional knowledge how to make it effective without restarting his session. However, I was aiming for one self-contained example which is easy to distribute so I wanted one file. Also I do not want to inflate the environment needlessly while the script is not in use. It is not a good practice, the environment space is limited. Thanks Michal ---
**Author:** ![Michal\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/779978/32.png) [@Michal\_S](https://www.ruby-forum.com/u/Michal_S)\ **Post date:** [May 25, 2010, 11:39pm UTC](https://www.ruby-forum.com/t/ruby-one-file-launcher-that-sets-up-environment/189054/4 "2010-05-25T23:39:43Z")
On 25 May 2010 21:56, Charles Oliver N. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > distribute so I wanted one file. > > Alternatively you can just throw everything in the same jar if there > aren’t file conflicts… The thing is that I do have to set the CLASSPATH for my application to work, and even set LD\_LIBRARY\_PATH in some cases, even if everything is in one jar. Also setting $CLASSPATH does not work anyway: java/lang/ClassLoader.java:1649:in `loadLibrary': java.lang.UnsatisfiedLinkError: Can't load library: /InsightToolkit.jar must be in CLASSPATH/libSwigRuntimeJava.so (NativeException) from java/lang/Runtime.java:787:in `load0’ from java/lang/Runtime.java:775:in `load' from InsightToolkit/itkbase.java:60:in `’ from InsightToolkit/itkImageFileReader\_2DJNI.java:1493:in `' from InsightToolkit/itkImageFileReaderF2.java:67:in `itkImageFileReaderF2\_New’ from ./testscript.rb:29 Thanks Michal ---
**Author:** ![Michal\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/779978/32.png) [@Michal\_S](https://www.ruby-forum.com/u/Michal_S)\ **Post date:** [May 25, 2010, 9:57pm UTC](https://www.ruby-forum.com/t/ruby-one-file-launcher-that-sets-up-environment/189054/5 "2010-05-25T21:57:16Z")
On Sun, May 23, 2010 at 5:18 PM, Michal S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Well, actually it does not. > > If I wanted to distribute the script in multiple files then > distributing it with a launcher would be just fine and would not > require the user of the script to have administrative privileges to > install the script in a system directory nor the additional knowledge > how to make it effective without restarting his session. > > However, I was aiming for one self-contained example which is easy to > distribute so I wanted one file. You can generally get by using the runtime CLASSPATH in JRuby: require ‘java’ $CLASSPATH \<\< ‘somefile.jar’ This doesn’t always work, since it’s using a child classloader in JRuby to handle all the classpath entries, but it often works well enough for a simple self-contained app. Alternatively you can just throw everything in the same jar if there aren’t file conflicts… - Charlie