Bash 中一系列数字的用例
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Using case for a range of numbers in Bash
提问by Luis Alvarado
I am trying to do the following using casein Bash (in Linux).
我正在尝试case在 Bash（在 Linux 中）中执行以下操作。
If X is between 460 and 660, output X information.
如果 X 在 460 到 660 之间，则输出 X 信息。
If X is between 661 and 800, do something else.
如果 X 介于 661 和 800 之间，请执行其他操作。
Etc.
等等。
Right now this is what I have:
现在这就是我所拥有的：
case $MovieRes in
[461-660]*) echo "$MovieName,480p" >> moviefinal ;;
[661-890]*) echo "$MovieName,720p" >> moviefinal ;;
[891-1200]*) echo "$MovieName,1080p" >> moviefinal ;;
*) echo "$MovieName,DVD" >> moviefinal ;;
esac
But somehow many of the ones that are 480p, 720p or 1080p are ending with DVD instead. The variable $MovieResis a simple list that shows, for each line, a number between 1 and 1200. Depending on the value, casedecides which "case" to apply.
但不知何故，许多 480p、720p 或 1080p 都以 DVD 结尾。该变量$MovieRes是一个简单的列表，它为每一行显示一个 1 到 1200 之间的数字。根据值，case决定应用哪种“案例”。
I would like to know how to actually use caseto accomplish this since it is a bit confusing when dealing with ranges like this.
我想知道如何实际使用case来实现这一点，因为在处理这样的范围时有点混乱。
回答by kev
In bash, you can use the arithmetic expression: ((...))
在 bash 中，您可以使用arithmetic expression：((...))
if ((461<=X && X<=660))
then
echo "480p"
elif ((661<=X && X<=890))
then
echo "720p"
elif ((891<=X && X<=1200))
then
echo "1080p"
else
echo "DVD"
fi >> moviefinal
回答by dogbane
The bash casestatement doesn't understand number ranges. It understands shell patterns.
bashcase语句不理解数字范围。它理解shell 模式。
The following should work:
以下应该工作：
case $MovieRes in
46[1-9]|4[7-9][0-9]|5[0-9][0-9]|6[0-5][0-9]|660) echo "$MovieName,480p" >> moviefinal ;;
66[1-9]|6[7-9][0-9]|7[0-9][0-9]|8[0-8][0-9]|890) echo "$MovieName,720p" >> moviefinal ;;
89[1-9]|9[0-9][0-9]|1[0-1][0-9][0-9]|1200) echo "$MovieName,1080p" >> moviefinal ;;
*) echo "$MovieName,DVD" >> moviefinal ;;
esac
However, I'd recommend you use an if-else statement and compare number ranges as in the other answer. A caseis not the right tool to solve this problem. This answer is for explanatory purposes only.
但是，我建议您使用 if-else 语句并比较其他答案中的数字范围。Acase不是解决这个问题的正确工具。此答案仅用于说明目的。
回答by Alvaro
Just for the pleasure of subverting case to do as you want,
you can use $((...))
只是为了颠覆案例的乐趣，你可以使用 $((...))
case 1 in
$(($MovieRes<= 460)))echo "$MovieName,???";;
$(($MovieRes<= 660)))echo "$MovieName,480p";;
$(($MovieRes<= 890)))echo "$MovieName,720p";;
$(($MovieRes<=1200)))echo "$MovieName,1080p";;
*)echo "$MovieName,DVD";;
esac >> moviefinal
回答by Mike Q
Similar issue which might be useful to someone ... Random additional thing I just tried out where it checks also that it is an integer, for me I wanted it to have a preset value, let the user change it, if they input the wrong data it sets to default.
类似的问题可能对某人有用......我刚刚尝试了随机附加的东西，它也检查它是否是一个整数，对我来说我希望它有一个预设值，如果他们输入错误，让用户更改它它设置为默认值的数据。
func_set_num_files(){
echo "How many files do you want to create? (input a number 1-10000)"
read X
# 1, is it a number, #2 is it within max range?
if [[ $X != *[!0-9]* ]]; then
if ((1<=X && X<=10000)) ;then
echo "NUM_FILES=$X"
NUM_FILES=$X
else
echo "Invalid input, setting to default value [ $NUM_FILES ].";sleep 3
fi
else
echo "Invalid input, non-numeric values entered, setting to default value [ $NUM_FILES ].";sleep 3
fi
}
Another example using 'case' to check that a variable is in a range of integers :
另一个使用 'case' 检查变量是否在整数范围内的示例：
check that $MAX is a number and that it's between 50-100 :
检查 $MAX 是一个数字并且它在 50-100 之间：
case $MAX in
''|*[!0-9]*)
echo "The value $MAX is not a number !"
exit 1
;;
*)
if [ $MAX -lt 50 ] || [ $MAX -gt 100 ] ;then
echo "The value $MAX is not between 50-100"
exit 1
fi
echo "Looks like we are good !"
;;
esac
回答by TheRusko0
I was looking for the simplest solution and found it difficult to use a case statementwith a number range.
我正在寻找最简单的解决方案，发现很难使用带有数字范围的case 语句。
Finally i found a really simple solution for zsh:
最后我找到了一个非常简单的zsh解决方案：
#!/usr/bin/zsh
case "${var}" in
<0-5461>)
printf "${var} is between 0 and 5461"
;;
<5462-10922>)
printf "${var} is between 5462-10922"
;;
esac
and for Bash:
对于Bash：
#!/bin/bash
case $((
(var >= 0 && var <= 5461) * 1 +
(var > 5462 && var <= 10922) * 2)) in
(1) printf "${var} is between 0 and 5461";;
(2) printf "${var} is between 5461 and 10922";;
esac
Hope it helps someone .
希望它可以帮助某人。
