bash 脚本和单个命令行中的 IF 语句
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IF statement in script and in a single command line
提问by 71GA
My script below checks for the instance of opened window in X server and it prints some info in the terminal depending on the state.
下面的脚本检查 X 服务器中打开的窗口的实例，并根据状态在终端中打印一些信息。
#!/bin/bash
if [[ -z $(xwininfo -tree -root | grep whatsapp | grep chromium) ]]
then
echo "IT DOES NOT EXIST";
else
echo "IT EXIST";
fi
When I try to rewrite this into a one line terminal command I do it like this:
当我尝试将其重写为一行终端命令时，我会这样做：
if -z $(xwininfo -tree -root | grep whatsapp | grep chromium); then echo "IT DOES NOT EXIST"; else echo "IT EXIST"; fi
this returns error and a wrong state...
这将返回错误和错误状态...
bash: -z: command not found
IT EXISTS
Does anyone have any advice? I tried asking the ShellCheckbut it says I have everything in order...
有人有建议吗？我尝试询问ShellCheck，但它说我已准备好一切...
采纳答案by 71GA
I got messed with an online bash code checker which stated that [[and ]]are not needed. This worked for me:
我弄乱了一个在线 bash 代码检查器，它指出[[并且]]不需要。这对我有用：
if [[ -z $(xwininfo -tree -root | grep whatsapp | grep chromium) ]]; then chromium --app=\"https://web.whatsapp.com/\"; fi & if [[ -z $(xwininfo -tree -root | grep skype | grep chromium) ]]; then chromium --app=\"https://web.skype.com/en/\"; fi & if [[ -z $(xwininfo -tree -root | grep Viber) ]]; then viber; fi
回答by Charles Duffy
Correctly following the advice from http://shellcheck.net/would have looked like the following:
正确遵循来自http://shellcheck.net/的建议看起来如下所示：
if xwininfo -tree -root | grep whatsapp | grep -q chromium; then
echo "IT DOES NOT EXIST";
else
echo "IT EXIST";
fi
...thus, in one-liner form:
...因此，以单行形式：
if xwininfo -tree -root | grep whatsapp | grep -q chromium; then echo "IT DOES NOT EXIST"; else echo "IT EXIST"; fi
See the wiki page for SC2143, the shellcheck warning you received.
请参阅SC2143的 wiki 页面，您收到的 shellcheck 警告。
