bash 如何简单地在bash中计算两个变量的最小值？
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how to calculate the minimum of two variables simply in bash?
提问by m-ric
I have a bash script checking the number of CPUs on the platform to efficiently use -joption for make, repo, etc. I use this:
我有一个 bash 脚本检查平台上的 CPU 数量以有效地使用-jmake、repo 等选项。我使用这个：
JOBS=$(cat /proc/cpuinfo | grep processor | tail -1 | sed "s,^.*:.*\([0-9].*\)$,,")
echo -e "4\n$JOBS" | sort -r | tail -1
It works fine. But, I am wondering if there was any built-in function which does the same thing (i.e. calculating the minimum, or maximum)?
它工作正常。但是，我想知道是否有任何内置函数可以做同样的事情（即计算最小值或最大值）？
回答by mvds
If you mean to get MAX(4,$JOBS), use this:
如果您想获取MAX(4,$JOBS)，请使用以下命令：
echo $((JOBS>4 ? JOBS : 4))
回答by Arnon Zilca
Had a similar situation where I had to find the minimum out of severalvariables, and a somewhat different solution I found useful was sort
有一个类似的情况，我必须从几个变量中找到最小值，我发现有用的一个有点不同的解决方案是sort
#!/bin/bash
min_number() {
printf "%s\n" "$@" | sort -g | head -n1
}
v1=3
v2=2
v3=5
v4=1
min="$(min_number $v1 $v2 $v3 $v4)"
I guess It's not the most efficient trick, but for a small constant number of variables, it shouldn't matter much - and it's more readable than nesting ternary operators.
我想这不是最有效的技巧，但对于少量恒定数量的变量，它应该没有太大关系 - 它比嵌套三元运算符更具可读性。
EDIT: Referring Nick's great comment - this method can be expanded to any type of sort usage:
编辑：参考尼克的精彩评论 - 此方法可以扩展到任何类型的排序用法：
#!/bin/bash
min() {
printf "%s\n" "${@:2}" | sort "" | head -n1
}
max() {
# using sort's -r (reverse) option - using tail instead of head is also possible
min r ${@:2}
}
min -g 3 2 5 1
max -g 1.5 5.2 2.5 1.2 5.7
min -h 25M 13G 99K 1098M
max -d "Lorem" "ipsum" "dolor" "sit" "amet"
min -M "OCT" "APR" "SEP" "FEB" "JUL"
