进程替换 - Node.js child_process

I'm trying to run a child process to modify a file (in two steps) before reading the modified content from stdout. I'm trying to do this by using process substitution which works perfectly in bash but not when i try it from node.

我正在尝试运行子进程来修改文件（分两步），然后再从stdout读取修改后的内容。我试图通过使用进程替换来做到这一点，它在bash中完美运行，但是当我从节点尝试时却没有。

This is kind of, what the command looks like..

这是什么，命令看起来像..

var p = exec('command2 <(capture /dev/stdout | command1 -i file -) -',
function (error, stdout, stderr) {
   console.log(stderr);
});

stderr prints:

stderr打印：

/bin/sh: -c: line 0: syntax error near unexpected token `('

What is the proper way of doing this in node?

在节点中执行此操作的正确方法是什么？

3 个解决方案

#1

I solved this by putting the commands in a shell script and calling the script from the node child process. I also needed to add the following to set bash in posix mode to allow process substitution:

我通过将命令放在shell脚本中并从节点子进程调用脚本来解决这个问题。我还需要添加以下内容以在posix模式下设置bash以允许进程替换：

set +o posix

There is probably a nicer way of doing this directly from within node but it did the job. Cheers!

可能有更好的方法直接从节点内执行此操作，但它完成了这项工作。干杯!

#2

You can spawn a child_process with bash substitution in Node by invoking the sh command with the -c flag.

您可以通过使用-c标志调用sh命令在Node中生成带有bash替换的child_process。

The sh command uses your default bash interpreter, and the -c flag asks the interpreter to read commands from within the string, Ie: $(echo $PATH). Additional flags are then passed to their normal positional references, such as: $0, $1, ect.

sh命令使用默认的bash解释器，-c标志要求解释器从字符串中读取命令，即：$（echo $ PATH）。然后将其他标志传递给它们的正常位置引用，例如：$ 0，$ 1等。

So an example might be:

所以一个例子可能是：

const spawn = require('child_process').spawn;

const prg = 'sh',

    args = [
        '-c',
        'echo $($0 $1)',
        'ls', // $0
        '-la' // $1
    ],

    opts = {
        stdio: 'inherit'
    };

// Print a directory listing, Eg: 'ls -la'
const child = spawn(prg, args, opts);

#3

you can have bash evaluate a command with bash -c 'command'. I've tested this and it works with process substitution and child_process.

你可以使用bash -c'命令'来bash评估一个命令。我测试了这个，它适用于进程替换和child_process。

#1