重定向bash while循环中的变量丢失
我有以下代码重定向bash while循环中的变量丢失,bash,while-loop,process-substitution,Bash,While Loop,Process Substitution,我有以下代码 for ip in $(ifconfig | awk -F ":" '/inet addr/{split($2,a," ");print a[1]}') do bytesin=0; bytesout=0; while read line do if [[ $(echo ${line} | awk '{print $1}') == ${ip} ]] then increment=$(echo ${lin
for ip in $(ifconfig | awk -F ":" '/inet addr/{split($2,a," ");print a[1]}')
do
bytesin=0; bytesout=0;
while read line
do
if [[ $(echo ${line} | awk '{print $1}') == ${ip} ]]
then
increment=$(echo ${line} | awk '{print $4}')
bytesout=$((${bytesout} + ${increment}))
else
increment=$(echo ${line} | awk '{print $4}')
bytesin=$((${bytesin} + ${increment}))
fi
done < <(pmacct -s | grep ${ip})
echo "${ip} ${bytesin} ${bytesout}" >> /tmp/bwacct.txt
done
我对Bash的理解是重定向的for循环应该保留变量。我做错了什么?首先,简化您的脚本!在bash中通常有很多更好的方法。大多数时候,您也可以依赖纯bash解决方案,而不是运行awk或其他工具。
然后添加一些去毛刺! 下面是一个带调试的重构脚本
#!/bin/bash
for ip in "$(ifconfig | grep -oP 'inet addr:\K[0-9.]+')"
do
bytesin=0
bytesout=0
while read -r line
do
read -r subIp _ _ increment _ <<< "$line"
if [[ $subIp == "$ip" ]]
then
((bytesout+=increment))
else
((bytesin+=increment))
fi
# some debugging
echo "line: $line"
echo "subIp: $subIp"
echo "bytesin: $bytesin"
echo "bytesout: $bytesout"
done <<< "$(pmacct -s | grep "$ip")"
echo "$ip $bytesin $bytesout" >> /tmp/bwacct.txt
done
#/bin/bash
对于“$(ifconfig | grep-oP'inet addr:\K[0-9.]+]”中的ip
做
bytesin=0
bytesout=0
而read-r行
做
read-r subIp uu uu u增量uu调试的可能重复:如果在循环中回送变量,它们是否包含非零值?这可以通过一些简单的调试轻松解决:打印所有相关变量。注意:为什么您更喜欢笨拙的${var}
表示法?此循环与最终的echo
运行在同一个shell中,因此建议的重复项不适用。这并不能解决您的问题,但看起来您可以使用:大大简化,同时读取ip a b增量c
,并保存所有awk
字段剪切。
#!/bin/bash
for ip in "$(ifconfig | grep -oP 'inet addr:\K[0-9.]+')"
do
bytesin=0
bytesout=0
while read -r line
do
read -r subIp _ _ increment _ <<< "$line"
if [[ $subIp == "$ip" ]]
then
((bytesout+=increment))
else
((bytesin+=increment))
fi
# some debugging
echo "line: $line"
echo "subIp: $subIp"
echo "bytesin: $bytesin"
echo "bytesout: $bytesout"
done <<< "$(pmacct -s | grep "$ip")"
echo "$ip $bytesin $bytesout" >> /tmp/bwacct.txt
done