bash 将结果保存到变量
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save result to variable
提问by user2129825
How can I save result from nc to the variable?
如何将结果从 nc 保存到变量？
I want:
我想要：
nc: connect to localhost port 1 (tcp) failed: Connection refused
nc：连接到本地主机端口 1 (tcp) 失败：连接被拒绝
on my variable. I tried:
在我的变量上。我试过：
a="$(nc -z -v localhost 1)"
echo $a
but output is empty.
但输出为空。
回答by fedorqui 'SO stop harming'
Just use $()to get the result of the command:
只是$()用来获取命令的结果：
your_var=$(nc -z -v localhost 1)
If you also want the error to be stored, then redirect the 2(error) to 1(normal output):
如果您还希望存储错误，则将2（错误）重定向到1（正常输出）：
your_var=$(nc -z -v localhost 1 2>&1)
回答by Micka?l Le Baillif
Just redirect stderrto stdout, expressed by 2>&1:
只需重定向stderr到stdout，表示为2>&1：
a="$(nc -z -v localhost 1 2>&1)"
echo $a
nc: connect to localhost port 1 (tcp) failed: Connection refused
File descriptor 2is attached (unless redirected) to stderr, and fd 1is attached to stdout. The bashsyntax $( ... )only captures stdout.
文件描述符2附加（除非重定向）到stderr，fd 1并附加到stdout。该 bash语法$( ... )仅捕获stdout。
回答by Anuj Sethi
-wis your friend in this case
-w在这种情况下是你的朋友
-w timeout Connections which cannot be established or are idle timeout after timeout seconds. The -w flag has no effect on the -l option, i.e. nc will listen forever for a connection, with or without the -w flag. The default is no timeout.
-w timeout 无法建立的连接或在 timeout 秒后空闲超时。-w 标志对 -l 选项没有影响，即 nc 将永远侦听连接，无论是否带有 -w 标志。默认是没有超时。
nc -z -w 3 $serverName $serverPort
Now you can use the $? variable to use it in your script.
现在您可以使用 $? 变量以在脚本中使用它。
if [ $? == 0 ]can be used to use the output of above command in the scripts.
Above command will timeout the connection after 3 seconds if it not able to establish.
if [ $? == 0 ]可用于在脚本中使用上述命令的输出。如果无法建立，上述命令将在 3 秒后超时连接。
