bash shell 脚本的可变参数
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Variable arguments to a shell script
提问by Kitcha
I would like to have my script accepting variable arguments. How do I check for them individually?
我想让我的脚本接受可变参数。我如何单独检查它们？
For example
例如
./myscript arg1 arg2 arg3 arg4
or
./myscript arg4 arg2 arg3
The arguments can be any number and in any order. I would like to check if arg4 string is present or not irrespective of the argument numbers.
参数可以是任何数字和任何顺序。无论参数编号如何，我都想检查 arg4 字符串是否存在。
How do I do that?
我怎么做？
Thanks,
谢谢，
回答by ruakh
The safest way — the way that handles all possibilities of whitespace in arguments, and so on — is to write an explicit loop:
最安全的方法——处理参数中所有可能的空格的方法，等等——是编写一个显式循环：
arg4_is_an_argument=''
for arg in "$@" ; do
if [[ "$arg" = 'arg4' ]] ; then
arg4_is_an_argument=1
fi
done
if [[ "$arg4_is_an_argument" ]] ; then
: the argument was present
else
: the argument was not present
fi
If you're certain your arguments won't contain spaces — or at least, if you're not particularly worried about that case — then you can shorten that to:
如果您确定您的参数不包含空格——或者至少，如果您不是特别担心这种情况——那么您可以将其缩短为：
if [[ " $* " == *' arg4 '* ]] ; fi
: the argument was almost certainly present
else
: the argument was not present
fi
回答by chbrown
This is playing fast and loose with the typical interpretation of command line "arguments", but I start most of my bash scripts with the following, as an easy way to add --helpsupport:
这是对命令行“参数”的典型解释的快速和松散，但我使用以下内容开始我的大多数 bash 脚本，作为添加--help支持的简单方法：
if [[ "$@" =~ --help ]]; then
echo 'So, lemme tell you how to work this here script...'
exit
fi
The main drawback is that this will also be triggered by arguments like request--help.log, --no--help, etc. (not just --help, which might be a requirement for your solution).
主要缺点是，这也将受到类似的论点被触发request--help.log，--no--help等等（不只是--help，这可能是您的解决方案的要求）。
To apply this method in your case, you would write something like:
要在您的情况下应用此方法，您可以编写如下内容：
[[ "$@" =~ arg4 ]] && echo "Ahoy, arg4 sighted!"
Bonus!If your script requires at least one command line argument, you can similarly trigger a help message when no arguments are supplied:
奖金！如果您的脚本至少需要一个命令行参数，则您可以在未提供任何参数时类似地触发帮助消息：
if [[ "${@---help}" =~ --help ]]; then
echo 'Ok first yer gonna need to find a file...'
exit 1
fi
which uses the empty-variable-substitution syntax ${VAR-default}to hallucinate a --helpargument if absolutely no arguments were given.
如果绝对没有给出参数，它使用空变量替换语法${VAR-default}来产生幻觉--help。
回答by Umae
maybe this can help.
也许这会有所帮助。
#!/bin/bash
# this is myscript.sh
[ `echo $* | grep arg4` ] && echo true || echo false
