如何创建动态 IF 条件

Question

我一直在写一个脚本，它将运行在 while 循环无限次中

如果满足所有条件，则只有脚本会中断并执行另一个命令

我的代码：

while true
do 
   
   # Note : below field will execute some command and generate value   
   field1=`some command which gives status`
   field2=`some command which gives status`
   field3=`some command which gives status`
   field4=`some command which gives status`

   if [ "$field1" == "A" ] &&  [ "$field2" == "A" ] && [ "$field3" == "A" ] && [ "$field4" == "A" ] 
   then
         break
   else
         echo "Conditions are not met !!!" 
   fi 
done

echo "Another command execution started ... "

这里的问题是字段数量可能会有所不同

需要使我的脚本通用，如果我有 10 个字段，它还应该构建一个

if 动态条件并开始执行，直到所有字段都等于 A 并中断以执行另一个命令

Answer 1

假设所有“成功”return状态为A，是单个字符长度。

我们可以将所有return状态码聚合成一个长字符串。比尝试搜索非 A 值。

local ret_val=""
while true; do 
   
   # Note : below field will execute some command and generate value   
   ret_val="${ret_val}$(some command1 which gives status)"
   ret_val="${ret_val}$(some command2 which gives status)"
   ret_val="${ret_val}$(some command3 which gives status)"
   ret_val="${ret_val}$(some command4 which gives status)"

   if [[ ${ret_val} =~ "[^A]*" ]]; then
     echo "Conditions are not met !!!" 
   else
     break
   fi 
done

echo "Another command execution started ... "

如果所有“成功”return 状态是一个 multi-digit 数字。

您可以将数字 return 状态转换为单个字符，请参阅此 answer。

Answer 2

是这样的吗？但这只适用于单行结果

A="A"
output="something to start"
until [ -z "$(echo $output | grep -v $A)" ]
do
    output=$(cat <<EOF
`cat A`  # First command
`cat B`  # Second command
EOF
)
    echo "Waiting for condition"
    sleep 1
done

你可以试试

echo "A" > A
echo "B" > B

停止条件

echo "A" > B

Answer 3

为字段使用数组可以循环遍历它们，将它放在函数中可以让您使用 return 结束执行，即使在多个嵌套循环中也是如此：

poll() {
  while true; do 
    declare -a fields=( )
    # Note : below field will execute some command and generate value   
    fields[1]=`some command which gives status`
    fields[2]=`some command which gives status`
    fields[3]=`some command which gives status`
    fields[4]=`some command which gives status`

    any_bad=0
    for field_idx in "${!fields[@]}"; do
      field_val=${fields[$field_idx]}
      if [[ $field_val != "A" ]]; then
        echo "Conditions not met (field $field_idx is not $field_val, not A)" >&2
        any_bad=1
        break
      fi
    done
    (( any_bad == 0 )) && return
  done
}
poll

Answer 4

因此只需检查 A 以外的任何行。

   res=$(
some command which gives status
some command which gives status
some command which gives status
some command which gives status
)
if <<<"$res" grep -xFqv A; then
     echo "Conditions is not met !!!"
fi

如何创建动态 IF 条件

How to create dynamic IF condition

shell

unix-text-processing