我对以下语法有点困惑。虽然它有效，但它不明白为什么它有效。似乎有两个管道连接到 diff 命令。但不是只有一个STDIN吗？
例子：
diff <(echo "foobar") <(echo "barbaz")
diff <(cat foo.txt) <(cat bar.txt)
我刚刚生成了一个新的 GPG 密钥对，gpg 显示了一些随机的加号、减号、大于、小于和抑扬符符号。我一直想知道他们是什么意思。你能给我解释一下吗？
iblue@nerdpol:~$ gpg --gen-key
[... snip ...]
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
.........+++............<+++++>.+++++...............>..+++++..<
...+++++............>+++++<.+++++.....................<+++++..>
.................................................+++++^^^^