bash 检查用户输入是否正确
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/848342/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Check user input is correct
提问by Johannes Schaub - litb
I wrote a bash script which takes numbers for calculation via user input. The problem I have is if the user types a letter or a space by mistake, the whole script fails and the user must start again.
我编写了一个 bash 脚本，它通过用户输入获取数字进行计算。我遇到的问题是，如果用户错误地输入了一个字母或一个空格，整个脚本就会失败，用户必须重新开始。
There must be an easy way to check the input is numeric only that will ask for the input again if anything else is input accidentally?
必须有一种简单的方法来检查输入是否仅为数字，如果不小心输入了其他任何内容，它将再次要求输入？
回答by Johannes Schaub - litb
Use a while loop
使用while循环
number=""
while [[ ! $number =~ ^[0-9]+$ ]]; do
echo Please enter your age
read number
done
echo You are $number years old
回答by lhunath
And to avoid the heavy regex engine, use a simple glob:
为了避免繁重的正则表达式引擎，请使用一个简单的 glob：
if [[ ! $input || $input = *[^0-9]* ]]; then
echo "Error: '$input' is not a number." >&2
fi
回答by Mike Q
Allows space before and after the number, _33, or 33___ , but not 3__3. and no letters. 0 or
允许数字前后有空格，_33 或 33___，但不允许 3__3。没有字母。0 或
-- Get input from user until Correct
-- 从用户获取输入直到正确
# -- get input until Correct
unset get_num
while [[ ! ${get_num} =~ ^[0-9]+$ ]]; do
echo "Please enter in a number:"
read get_num
done
echo This is a number : ${get_num}
-- Get input until Correct (within range)
-- 获取输入直到正确（在范围内）
# -- get input until Correct (within range)
unset get_num
while [[ ! ${get_num} =~ ^[0-9]+$ ]]; do
echo "Please enter in a number within range of (1-30):"
read get_num
! [[ ${get_num} -ge 1 && ${get_num} -le 30 ]] && unset get_num
done
echo This is a number withn a range : ${get_num}
-- get input until Correct (within range) (full regex way)
-- 获取输入直到正确（在范围内）（完整的正则表达式方式）
"Since regular expressions deal with text rather than with numbers, matching a number in a given range takes a little extra care. You can't just write [0-255] to match a number between 0 and 255. Though a valid regex, it matches something entirely different. [0-255] is a character class with three elements: the character range 0-2, the character 5 and the character 5 (again). This character class matches a single digit 0, 1, 2 or 5, just like [0125]." ~ http://www.regular-expressions.info/numericranges.html
“由于正则表达式处理的是文本而不是数字，因此匹配给定范围内的数字需要格外小心。你不能只写 [0-255] 来匹配 0 到 255 之间的数字。虽然是一个有效的正则表达式，它匹配完全不同的东西。[0-255] 是一个包含三个元素的字符类：字符范围 0-2、字符 5 和字符 5（再次）。这个字符类匹配单个数字 0、1、2 或5，就像[0125]一样。” ~ http://www.regular-expressions.info/numericranges.html
# -- get input until Correct (within range) (another way)
unset get_num
while [[ ! ${get_num} =~ ^([1-9]|1[0-9]|2[0-9]|30)$ ]]; do
echo "Please enter in a number within range of (1-30):"
read get_num
done
echo This is a number withn a range : ${get_num}
-- Get input, and check it only (no while loop)
-- 获取输入，并只检查它（没有 while 循环）
# -- get input, and check it only (no while loop)
unset get_num
echo "Please enter in a number:"
read get_num
if [[ ! ${get_num} =~ ^[0-9]+$ ]] ;then
echo "${get_num} isn't a number"
else
echo "${get_num} is a number"
fi
