无法获取管道内设置shell变量的准确值

Question

我想设置一个变量的基础上，MySQL的声明是这样的执行结果：

errorOut=0 
    mysql -uroot -pinsite3 -rN --execute "select file_system_id from ifm.PartitionTable where physical_partition='$partName'" | while read myVal 
    do 
     echo "myVal = $myVal" 
     if [ $myVal -eq $fsId ];then 
     errorOut=1 
     echo "Found equal: errorOut = $errorOut" 
     fi 
    done 
    echo "Outside loop: errOut = $errorOut" 


Here is the output: 
myVal = 1 
myVal = 2 
Found equal: errorOut = 1 
Outside loop: errOut = 0 

正如你所看到的，由于管道我无法获得循环外的变量的值（因为管道内的变量，基本上设置分叉不同的过程）

有没有什么办法可以提取循环外的实际值？

Answer 1

如果您使用for...in而不是read，那么该怎么办？ ：

errorOut=0 
for myVal in $(mysql -uroot -pinsite3 -rN --execute "select file_system_id from ifm.PartitionTable where physical_partition='$partName'") 
do 
    echo "myVal = $myVal" 
    if [ $myVal -eq $fsId ];then 
    errorOut=1 
    echo "Found equal: errorOut = $errorOut" 
    fi 
done 
echo "Outside loop: errOut = $errorOut" 

Answer 2

将其写入文件，然后在循环外读取文件。

errorOut=0 
errOutFile=Err$$.txt 
mysql -uroot -pinsite3 -rN --execute "select file_system_id from ifm.PartitionTable where physical_partition='$partName'" | while read myVal 
do 
    echo "myVal = $myVal" 
    if [ $myVal -eq $fsId ];then 
    errorOut=1 
    echo "Found equal: errorOut = $errorOut" 
    echo "$errorOut" > $errOutFile 
    fi 
done 
errorOut="$(cat $errOutFile)"