Node.js shebang line and NODE_OPTIONS #109

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1. Knighton910

   added

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   on Mar 15, 2016
2. megastef commented on Mar 31, 2016

   

   megastef

   on Mar 31, 2016

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   Should i open an issue in node/node repository?
3. MylesBorins commented on Mar 31, 2016

   

   MylesBorins

   on Mar 31, 2016

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   hey @megastef I help maintain canary in the gold mine, a cli + library for testing node packages. You might find some of the patterns we use in there useful

   https://github.com/nodejs/citgm/

   I'm not 100% I'm following what you shebang logic is doing, but I usually start a bin with #!/usr/bin/env node as you can see here https://github.com/nodejs/citgm/blob/master/bin/citgm#L1

   If you want to include arguments to node you can just append them on that line

   in your case

   #!/usr/bin/env node --max_old_space_size=100
   console.log('sup 100');

   This was the correct place to ask the question, thanks for your patience!

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4. megastef commented on Mar 31, 2016

   

   megastef

   on Mar 31, 2016

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   I want to give the user full control on node Options - /bin/env node might fail on ubuntu, the binary might be named 'nodejs'. My shebang line tries to catch this case. The second problem is that options might have underscore or dash (i assume this is a compile time config e.g on CentOS). Well, this migh be a fight with legacy node versions. Thx.
5. martinheidegger commented on Mar 31, 2016

   

   martinheidegger

   on Mar 31, 2016

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   To answer let me explore the functionality of the shebang a little: The shebang is a reference to the application that launches the current script file. #!/bin/bash refers to a bash application. Interestingly - unlike bash - the node binary is not at the same place in every system. #!/usr/bin/env on the other hand is a binary on the same place and it knows how to start a local command so #!/usr/bin/env node passes in the argument node to env and env is so cool to start this for us.

   Recap: #!<command> <args> is the signature of a shebang

   It would be easy if you could just pass in the arguments like #!/usr/bin/env node $@ but a test.sh with this content: #!echo $@ will print $@ test.sh That means: the shebang can not take arguments from the command line

   The only option to start node with dynamic arguments is to start it in a child process. Now: We could make this complicated and write it in a separate file or we could do something like this:

   #!/bin/bash
   
   content () {
   cat <<JavaScript
   
     console.log("hi")
   
   JavaScript
   }
   
   content | /usr/bin/env node $@

   This way all the parameters are passed in to the node sub process. If you add some parameter check's to the bash script you could even decide which node parameters are okay to pass-in and which are not.

   If you can tell env to use an alias of node instead of node, then you are all setup already! Unfortunately I have not yet figured out how. more here

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6. megastef commented on Mar 31, 2016

   

   megastef

   on Mar 31, 2016

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   Hi @martinheidegger, long time not seen :)
   My shebang line works fine. Setting memory default, detecting node binary name, and taking custom NODE_OPTIONS.

   #!/bin/sh
   ':' //; export MAX_MEM="--max-old-space-size=100"; exec "$(command -v node || command -v nodejs)" "${NODE_OPTIONS:-$MAX_MEM}" "$0" "$@" 
   

   Actually I had the hope that the Node.js binary could take options from an (undocumented?) environment variable or resource file. But it looks we have to live with shell tricks to inject this parameters.

   I think it would be a good feature for node to respect e.g. NODE_OPTIONS environment variable.
7. martinheidegger commented on Mar 31, 2016

   

   martinheidegger

   on Mar 31, 2016

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   A test.sh script with the shebang

   #!echo $FOO

   would result in $FOO test.sh when called using env FOO=bar. As such I assume that you can't simply pass in environment variables as NODE_OPTIONS would not do much help in the shebang.

   I also think that it might be a bad idea to have this option in a file since the properties would apply to any node process running. I kind-of still think that the current way to do it seems right.
8. megastef

   closed this as completedon Apr 4, 2016