一种方法是使用正则表达式，如下所示:

One approach is to use a regular expression, like so:

re='^[0-9]+$'
if ! [[ $yournumber =~ $re ]] ; then
   echo "error: Not a number" >&2; exit 1
fi

如果该值不一定是整数，请考虑适当修改正则表达式；例如:

If the value is not necessarily an integer, consider amending the regex appropriately; for instance:

^[0-9]+([.][0-9]+)?$

...或者，处理带符号的数字:

...or, to handle numbers with a sign:

^[+-]?[0-9]+([.][0-9]+)?$