bash 如何检查传递给 shell 脚本的参数是否不是整数？
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How can I check whether an argument passed to a shell script is NOT an integer?
提问by Explosion Pills
I know how to check whether an argument is an integer using:
我知道如何使用以下方法检查参数是否为整数：
if [[ = *[[:digit:]]* ]]; then
# is a number
else
# is not a number
fi
However, I need to check whether the argument is nota integer. How can I do that?
但是，我需要检查参数是否不是整数。我怎样才能做到这一点？
回答by Explosion Pills
$2 = *[[:digit:]]*only checks whether $2containsa digit.
$2 = *[[:digit:]]*只检查是否$2包含数字。
# is an integer
[[ =~ ^[[:digit:]]+$ ]]
# is not an integer
[[ ! =~ ^[[:digit:]]+$ ]]
回答by jub0bs
A POSIX-compliant approach
符合 POSIX 的方法
A robust and portable (POSIX-compliant; tested in dash) approach is to check whether the shell can parse the variable as an integer, as demonstrated in the script below.
一种健壮且可移植（符合 POSIX 标准；在 中测试dash）的方法是检查 shell 是否可以将变量解析为整数，如下面的脚本所示。
#!/bin/sh
# test-int.sh
# A script that tests whether its first argument is an integer
if [ "" -eq 0 -o "" -ne 0 ] >/dev/null 2>&1; then
printf "integer: %s\n" ""
else
printf "not an integer\n"
fi
Tests
测试
$ dash test-int.sh foo
not an integer
$ dash test-int.sh 098234
integer: 098234
$ dash test-int.sh 77239asdfasf
not an integer
$ dash test-int.sh -77239
integer: -77239
Note that this approach also accepts negative integers out of the box, but you can easily modify it to only accept positive integers, for instance.
请注意，此方法还接受开箱即用的负整数，但您可以轻松地将其修改为仅接受正整数。
In my script, a successfully parsed integer is printed as a string, but, alternatively, you may want to print it as an integer, with %d.
在我的脚本中，成功解析的整数打印为string，但是，或者，您可能希望将其打印为integer，使用%d.
回答by The Dark Knight
Quite easy you know . You can do this :
很容易你知道。你可以这样做 ：
if echo $Myvar | egrep -q '^[0-9]+$'; then
# $Myvar is a number
else
# $Myvar is not a number
fi
This is some thing that i predominantly use for a number check.
这是我主要用于数字检查的一些东西。
回答by Till Varoquaux
You test only checks whether the input is a digit; for example is $2 is "43" then this will print: 43 is not a number Fixing your solution to check for actual numbers can be done with a regular expression:
您测试只检查输入是否为数字；例如 $2 是 "43" 那么这将打印： 43 is not a number 修复您的解决方案以检查实际数字可以使用正则表达式完成：
if [[ =~ ^-?[[:digit:]]+$ ]]; then
echo " is a number"
fi
Checking whether the input is not a number is then just a matter of negating the test:
检查输入是否不是数字只是否定测试的问题：
if [[ ! =~ ^-?[[:digit:]]+$ ]]; then
echo " is not a number"
fi
