mathjs/examples/node_modules/cross-spawn/lib/util/readShebang.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with dif

'use strict';

const fs = require('fs');
const shebangCommand = require('shebang-command');

function readShebang(command) {
    // Read the first 150 bytes from the file
    const size = 150;
    const buffer = Buffer.alloc(size);

    let fd;

    try {
        fd = fs.openSync(command, 'r');
        fs.readSync(fd, buffer, 0, size, 0);
        fs.closeSync(fd);
    } catch (e) { /* Empty */ }

    // Attempt to extract shebang (null is returned if not a shebang)
    return shebangCommand(buffer.toString());
}

module.exports = readShebang;