bash `and` 和 `or` 在一个 awk 命令中的多个条件
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multiple conditions of `and` and `or` in one awk command
提问by user7352907
I am trying to use multiple 'AND' and 'OR' condition in awk but it is not giving me the desired output. Instead it doesn't read the last &&conditions that i have given with time '030000'.
我试图在 awk 中使用多个“AND”和“OR”条件，但它没有给我想要的输出。相反，它不会读取&&我在时间“030000”时给出的最后条件。
awk -F, '{if(substr(,1,3)=="301" && =="996" || =="429" && >=030000 && <=035000) print "|""|"}' 2017020* | head -10
3014241320|996|235939
3017943809|996|235953
采纳答案by hek2mgl
Looks like you missed parentheses around the ORoperation. It should be:
看起来您错过了OR操作周围的括号。它应该是：
if(substr(,1,3)=="301" && (=="996" || =="429") && >=030000 && <=035000) ...
See boolean algebra.
请参阅布尔代数。
回答by aferber
In awk, &&has higher precedence than ||, so your condition actually means
在 awk 中，&&优先级高于||，因此您的条件实际上意味着
(substr(,1,3)=="301" && =="996")
||
(=="429" && >=030000 && <=035000)
Your tests for $5are only applied to lines where $15=="429"is true, which isn't the case in your example output lines.
您的测试$5仅适用于$15=="429"为真的行，而在您的示例输出行中并非如此。
Use parentheses to change that:
使用括号来改变它：
awk -F, '{if(substr(,1,3)=="301" && (=="996" || =="429") && >=030000 && <=035000) print "|""|"}' 2017020* | head -10
As a general rule, I would always parenthesize expressions with mixed logical AND and OR in any language even if not strictly necessary. This aids readability and avoids nasty surprises (there are languages out there with different precedence for AND and OR...).
作为一般规则，即使不是绝对必要的，我也会在任何语言中用混合的逻辑 AND 和 OR 将表达式括起来。这有助于提高可读性并避免令人讨厌的意外（有些语言对 AND 和 OR 具有不同的优先级......）。
