jq具有来自不同来源的多个输入

问题描述：

使用jq时如何混合不同的输入源? 对于特定的用例，我想将文件中的一些数据添加到标准输出中通过管道传输的Feed中.

How can we mix different input sources when using jq ? For a specific usecase, I'd like to add some data from a file into a feed that was pipe in stdout.

$ echo '[{"a": 1}]' > /tmp/a1
$ echo '[{"a": 2}]' > /tmp/a2
$ jq --slurp '.[0] + .[1]' /tmp/a1 /tmp/a2
[
  {
    "a": 1
  },
  {
    "a": 2
  }
]
$ cat /tmp/a1 | jq --slurp '.[0] + .[1]' /tmp/a2  # Expecting the same result
[
  {
    "a": 2
  }
]

如您所见，最后一个命令没有解释管道数据.

As you can see, the last command didn't interpret the piped data.

现在，我被迫将第一个操作的输出保存到一个临时文件中，以便我可以执行jq合并操作，然后再将其发送回网络.拥有单个流会更有效率

Right now, I'm forced to save the output from the first operation into a temporary file, so that I can do the jq merging operation, before sending it back to the network. Having a single stream would be much more efficient

答

我想将文件中的某些数据添加到标准输出中通过管道传输的Feed中.

I'd like to add some data from a file into a feed that was pipe in stdout.

有多种方法可以执行此操作，具体取决于外壳以及所使用的jq的版本.

There are various ways to do this, depending on the shell and also the version of jq you are using.

假设您的jq支持--argfile选项，您可能会发现它很合适:

Assuming your jq supports the --argfile option, you might find that quite congenial:

cat /tmp/a1 | jq --argfile a2 /tmp/a2 '. + $a2'

这是另一个变种，它暗示了其他一些可能性:

Here is another variation that suggests some of the other possibilities:

jq -n --argfile a1 <(cat /tmp/a1) --argfile a2 <(cat /tmp/a2) '$a1 + $a2'

更有趣的是:

(cat /tmp/a1 ; cat /tmp/a2) | jq '. + input'

最后是一种适用于每个jq版本的方法:

And finally an approach that should work for every version of jq:

jq -s '.[0] + .[1]' <(cat /tmp/a1) /tmp/a2

但是，通常最好避免使用-s选项.

In general, though, it's best to avoid the -s option.

如果您比较由以下人员产生的输出:

If you compare the outputs produced by:

echo '1 2' |
  jq -s --debug-dump-disasm --debug-trace  '.[0], .[1]'

和

echo '1 2' |
  jq --debug-dump-disasm --debug-trace  '., input'

您会注意到，前者必须使用PUSHK_UNDER来存储整个数组[1,2]，而后一个程序只是分别读取两个输入.

you'll notice the former has to PUSHK_UNDER to store the entire array [1,2], whereas the latter program just reads the two inputs separately.

在第一个程序中，要等到之后才能释放阵列的内存指向它的所有指针都已被处理，而在第二个程序中，的记忆.可以在第一个RET之后释放.

In the first program, the memory for the array cannot be freed until after all the pointers into it have been processed, whereas in the second program, the memory for . can be freed after the first RET.

jq具有来自不同来源的多个输入

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