shebang

Is there a standard way to make sure a python script will be interpreted by python2 and not python3? On my distro, I can use #!/usr/bin/env python2 as the shebang, but it seems not all distros ship "python2". I could explicitly call a specific version (eg. 2.6) of python, but that would rule out people who don't have that version. It seems to me that this is going to be increasingly a problem when distros will start putting python3 as the default python interpreter. This is a bit of a messy issue during what will be a very long transition time period. Unfortunately, there is no fool-proof,

Given that Java 9 is upon us and we can finally have a java REPL with jshell I was hoping there was a way to add a shebang to a script and have jshell interpret it. I tried creating test.jsh : #!/usr/bin/env jshell -s System.out.println("Hello World") /exit However that gives: ⚡ ./test.jsh | Error: | illegal character: '#' | #!/usr/bin/env jshell -s | ^ | Error: | illegal start of expression | #!/usr/bin/env jshell -s | ^ Hello World It turns out there is an enhancement request for this in OpenJDK https://bugs.openjdk.java.net/browse/JDK-8167440 . Is there any other way to do this? Use //usr

what is the use of writing the following command at the start of a ruby program ? #!/usr/local/bin/ruby -w Is it OS specific command? Is it valid for ruby on windows ? if not, then what is an equivalent command in windows ? The Shebang line is optional, and if you run the ruby interpreter and pass the script to it as a command line argument, then the flags you set on the command line are the flags ruby runs with. A Shebang line is not ruby at all (unless you want to call it a ruby comment). It's really shell scripting. Most linux and unix users are running the BASH shell (stands for Borne

My Python script beak contains the following shebang: #!/usr/bin/env python When I run the script $ ./beak , I get env: python\r: No such file or directory I previously pulled this script from a repository. What could be the reason for this? falsetru The script contains CR characters. The shell interprets these CR characters as arguments. Solution: Remove the CR characters from the script using the following script. with open('beak', 'rb+') as f: content = f.read() f.seek(0) f.write(content.replace(b'\r', b'')) f.truncate() Open the file in vim or vi, and administer the following command: :set

I used to use the shebang #!/usr/bin/env python When is it better to use #!/usr/bin/python What is the exact difference between them? vartec #!/usr/bin/python is hardcoded to always run /usr/bin/python , while #!/usr/bin/env python will run whichever python would be default in your current environment (it will take in account for example $PATH , you can check which python interpreter will be used with which python ). The second way ( #!/usr/bin/env python ) is preferred , as it's not dependent on particular installation. It will work for example with virtualenv setups or systems where there is

Some scripting languages (such as Python or Bash) use # for comments. #!/usr/bin/env python print 'hello, world' I can run the script: python script.py Or ./script.py Is it possible to make JavaScript support shebang? Yes, you can simply use #!/usr/bin/env node (or whatever the name of your JavaScript interpreter is, it works fine with js (spidermonkey), too). [me@hades:~]> cat > test.js #!/usr/bin/env node console.log('hi'); [me@hades:~]> chmod +x test.js [me@hades:~]> ./test.js hi Most likely both interpreters test if the first line begins with #! and in this case it is skipped. 来源： https:/