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I found serval node.js projects that have this at top of their app.js (as in this openshift program):

#!/bin/env node

What does this mean? How does this work? Where is it useful?

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The full line from your example is:

#!/bin/env node

This simply means that the script should be executed with the first executable named 'node' that's found in your current PATH.

The shebang (#!) at the start means execute the script with what follows. /bin/env is a standard unix program that looks at your current environment. Any argument to it not in a 'name=value' format is a command to execute. See your env manpage for further details.

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    In general, do I need add this declare in my node app?
    – hh54188
    Feb 25, 2013 at 6:29
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    Only if you want to be able to start it using ./app.js instead of needing to type node app.js. For an example where it's useful have a look at stackoverflow.com/questions/14517535/…
    – Golo Roden
    Feb 25, 2013 at 8:03
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    Type 'which env' to get the path on your local system. It may be installed in /usr/bin/env instead, for example.
    – sockmonk
    Feb 18, 2014 at 16:12
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    @chovy ... A bit late, but for osx I symlink env into bin: sudo ln -s /usr/bin/env /bin/env
    – Paul J
    Aug 14, 2015 at 0:13
  • @AndrewLam #!/usr/bin/env node is the right spelling. Some platforms have /bin/env as well as /usr/bin/env, but those are typically because /bin is the same as /usr/bin. If you're asking whether that works on only linux/unix flavors vs. windows, it depends - if you use cygwin or other flavors of , then yes, that will work, but if you just want to execute from a windows explorer window or windows command prompt (or power shell) then the #! sequence to indicator what interpreter to use won't help. On both windows and unix, you can run 'node app.js' and whatever you have for #! is irrelevant.
    – Juan
    Jan 18, 2019 at 18:18
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env is a shell command used to specify an interpreter.

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    In plain English that means env will find the location of node in your $PATH. People sometimes do #!/bin/node or #!/usr/local/bin/node but the problem is, you don't know where the person may have their copy of node. So env program finds that for you.
    – Mauvis Ledford
    Feb 25, 2013 at 6:19

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