How to combine Bash's process substitution with HERE-document?

 You can combine Bash's process substitution with a HERE-document to feed the output of a command into a command that expects input from a file or standard input. Here's an example of how to do this:


```bash

command1 < <(command2 <<EOF

This is the content of the HERE-document.

You can include multiple lines.

EOF

)

```


In this example:


- `command2` is a command that reads from a HERE-document.

- The `<<EOF` syntax is used to define the HERE-document. You can choose any marker (e.g., `<<END`), but it should match the marker used within the `command2`.

- The content of the HERE-document is provided between the `<<EOF` and `EOF` markers.


The `< <(command2 ...)` part is where process substitution comes into play. It takes the output of the HERE-document and provides it as input to `command1`. This is especially useful when `command1` expects input from a file or standard input, and you want to provide the content from the HERE-document dynamically.


Here's a practical example using `cat` to read the content of the HERE-document and `grep` to search for a specific pattern:


```bash

grep pattern < <(cat <<EOF

This is some text containing the pattern.

You can search for it using process substitution.

EOF

)

```


In this example, `cat` reads the HERE-document's content, and `grep` searches for the specified pattern within that content.

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