shebang
How to execute a java script with jshell?
Use //usr/bin/env jshell –show-version –execution local “$0” “$@”; exit $? as the first line of test.jsh. The test.jsh script could look like: //usr/bin/env jshell –show-version “$0” “$@”; exit $? System.out.println(“Hello World”) /exit The command line option –show-version is optional, of course, but gives immediate feedback that the tool is running. The extra command line option … Read more
Why should the shebang line always be the first line?
The shebang must be the first line because it is interpreted by the kernel, which looks at the two bytes at the start of an executable file. If these are #! the rest of the line is interpreted as the executable to run and with the script file available to that program. (Details vary slightly, … Read more
Shebang line limit in bash and linux kernel
Limited to 127 chars on 99.9% of systems due to kernel compile time buffer limit. It’s limited in the kernel by BINPRM_BUF_SIZE, set in include/linux/binfmts.h.
How can I use a shebang in a PowerShell script?
Quick note for Linux/macOS users finding this: Ensure the pwsh or powershell command is in PATH Use this interpreter directive: #!/usr/bin/env pwsh Ensure the script uses Unix-style line endings (\n, not \r\n) Thanks to briantist’s comments, I now understand that this isn’t directly supported for PowerShell versions earlier than 6.0 without compromises: …[in PowerShell Core … Read more
what is the use of “#!/usr/local/bin/ruby -w” at the start of a ruby program
It is called a Shebang. It tells the program loader what command to use to execute the file. So when you run ./myscript.rb, it actually translates to /usr/local/bin/ruby -w ./myscript.rb. Windows uses file associations for the same purpose; the shebang line has no effect (edit: see FMc’s answer) but causes no harm either. A portable … Read more
Use shebang/hashbang in Windows Command Prompt
Yes, this is possible using the PATHEXT environment variable. Which is e.g. also used to register .vbs or .wsh scripts to be run “directly”. First you need to extend the PATHEXT variable to contain the extension of that serve script (in the following I assume that extension is .foo as I don’t know Node.js) The … Read more
Invoking a script, which has an awk shebang, with parameters (vars)
Try using: #!/usr/bin/awk -f as an interpreter
shebang: use interpreter relative to the script path
There is a healthy set of multi-line shebang scripts on this page for a lot of languages, example: #!/bin/sh “exec” “`dirname $0`/python” “$0” “$@” print copyright And if you want one-line shebang, this answer (and question) explains the issue in the details and suggests the following approaches using additional scripts inside the shebang: Using AWK … Read more
Should I use a Shebang with Bash scripts?
On UNIX-like systems, you should always start scripts with a shebang line. The system call execve (which is responsible for starting programs) relies on an executable having either an executable header or a shebang line. From FreeBSD’s execve manual page: The execve() system call transforms the calling process into a new process. The new process … Read more