bash：在 if 语句中使用 grep，防止回声
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bash: using grep in if statement, prevent echo
提问by Chris Seymour
I have this bash script:
我有这个 bash 脚本：
#!/bin/bash
external_output="Oliver's AirPort Express"
if ~/.bin/audiodevice | grep "$external_output"
then
~/.bin/audiodevice output "Internal Speakers"
echo "Internal Speakers"
else
~/.bin/audiodevice output "$external_output"
echo "Oliver's AirPort Express"
fi
If the grepis matched, then it of course echoes the match. As I am using it in an if statement, I don't want this to echo.
如果grep匹配，那么它当然会回显匹配。当我在 if 语句中使用它时，我不希望它回响。
How can I use grepin my ifstatement without having it announce the result to me when I run the script?
如何grep在我的if语句中使用而不在我运行脚本时向我宣布结果？
回答by Chris Seymour
You want grep -q "$external_output"to suppress the output. From man grep:
您想grep -q "$external_output"抑制输出。来自man grep：
-q, --quiet, --silent
Quiet; do not write anything to standard output. Exit immediately with zero status if any match is found, even if an error was detected (-q is specified by POSIX).
-q, --quiet, --silent
安静的; 不要向标准输出写入任何内容。如果找到任何匹配项，则立即以零状态退出，即使检测到错误（-q 由 POSIX 指定）。
