Bash 测试参数是否存在
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Bash test if an argument exists
提问by Aleksandr Levchuk
I want to test if an augment (e.g. -h) was passed into my bash script or not.
我想测试是否将增强（例如 -h）传递到我的 bash 脚本中。
In a Ruby script that would be:
在 Ruby 脚本中：
#!/usr/bin/env ruby
puts "Has -h" if ARGV.include? "-h"
How to best do that in Bash?
如何在 Bash 中最好地做到这一点？
回答by Jonathan Leffler
It is modestly complex. The quickest way is also unreliable:
它是适度复杂的。最快的方法也不可靠：
case "$*" in
(*-h*) echo "Has -h";;
esac
Unfortunately that will also spot "command this-here" as having "-h".
不幸的是，这也会发现“ command this-here”具有“ -h”。
Normally you'd use getoptsto parse for arguments that you expect:
通常你会getopts用来解析你期望的参数：
while getopts habcf: opt
do
case "$opt" in
(h) echo "Has -h";;
([abc])
echo "Got -$opt";;
(f) echo "File: $OPTARG";;
esac
done
shift (($OPTIND - 1))
# General (non-option) arguments are now in "$@"
Etc.
等等。
回答by kitingChris
The simplest solution would be:
最简单的解决方案是：
if [[ " $@ " =~ " -h " ]]; then
echo "Has -h"
fi
回答by Aleksandr Levchuk
#!/bin/bash
while getopts h x; do
echo "has -h";
done; OPTIND=0
As Jonathan Leffler pointed out OPTIND=0 will reset the getopts list. That's in case the test needs to be done more than once.
正如 Jonathan Leffler 指出的那样 OPTIND=0 将重置 getopts 列表。以防万一测试需要进行多次。
回答by keyvan
I found the answer in a dupe question here: https://serverfault.com/questions/7503/how-to-determine-if-a-bash-variable-is-empty
我在这里找到了一个欺骗性问题的答案：https: //serverfault.com/questions/7503/how-to-determine-if-a-bash-variable-is-empty
See my function mt() below for an example usage:
有关示例用法，请参阅下面的函数 mt()：
# mkdir -p path to touch file
mt() {
if [[ -z ]]; then
echo "usage: mt filepath"
else
mkdir -p `dirname `
touch
fi
}
