Linux 将命令输出重定向到 bash 中的变量失败
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Redirecting command output to a variable in bash fails
提问by roman
I'm trying to redirect command output to a variable:
我正在尝试将命令输出重定向到一个变量：
OUTPUT=$(sudo apache2ctl configtest)
and then to read it:
然后阅读它：
echo $OUTPUT
When running it the output is the following:
运行时输出如下：
19:19:12 user@user ~ OUTPUT=$(sudo apache2ctl configtest)
Syntax OK
Syntax OK
But the variable stays blank. I've tried the same for other commands and everything works fine.
但变量保持空白。我已经对其他命令尝试了相同的方法，一切正常。
OUTPUT=$(ls -l)
This writes file list to variable OUTPUTso that it can be read later.
What should i do to make it work?
这会将文件列表写入变量，OUTPUT以便稍后读取。我应该怎么做才能使它工作？
采纳答案by johnshen64
maybe the output goes to stderr, not stdout?
也许输出去stderr，不是stdout？
try this: OUTPUT=$(sudo apache2ctl configtest 2>&1)
尝试这个： OUTPUT=$(sudo apache2ctl configtest 2>&1)
回答by beliy
For nginx possible situation when configtest can be successful with error in config files. Example:
对于 nginx 可能的情况，当 configtest 可以成功但配置文件中出现错误时。例子：
nginx: [warn] conflicting server name "test.com" on 0.0.0.0:80, ignored
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
for correct check errors in bash scripts need use:
为了正确检查 bash 脚本中的错误，需要使用：
if [[ $((sudo /sbin/service nginx configtest) 2>&1 | grep "failed\|warn" ) ]]; then
echo "ERROR!!!"
else
echo "OK!!!"
fi
