Process substitution is written using parentheses and behind the scenes uses named pipes.

#### Example 1
```plaintext
cat <(ls) <(echo hello)
```
This takes the command `ls` and sends its output to a named pipe (say `pipe_a`), does similar with the echo command, to say `pipe_b`, and then runs `cat` as
```plaintext
cat pipe_a pipe_b
```
The actual pipe filenames will look something like 
```plaintext
/dev/fd/11
```
as you can verify by running e.g.
```plaintext
echo <(ls)
```

Note that this does //not// use stdin, and requires that the command (here `cat`) reads from files specified on the command line.