如何编写一个带有可选输入参数的bash脚本？

最新推荐文章于 2024-04-25 16:39:08 发布

翻译最新推荐文章于 2024-04-25 16:39:08 发布 · 773 阅读

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原文链接：https://oldbug.net/q/d9t4/How-to-write-a-bash-script-that-takes-optional-input-arguments

文章标签：

#bash #arguments #parameter-passing

本文介绍了如何在bash脚本中添加可选输入参数。通过设置默认值和利用变量替换，可以实现参数的灵活性。文章提供了一些示例，包括处理带有空格的文件路径的问题，并展示了一种方法，允许脚本接受日期作为可选参数。

本文翻译自：How to write a bash script that takes optional input arguments?

I want my script to be able to take an optional input, 我希望我的脚本能够获取可选输入，

eg currently my script is 例如，目前我的剧本是

#!/bin/bash
somecommand foo

but I would like it to say: 但我想说：

#!/bin/bash
somecommand  [ if $1 exists, $1, else, foo ]

#1楼

参考：https://stackoom.com/question/d9t4/如何编写一个带有可选输入参数的bash脚本

#2楼

please don't forget, if its variable $1 .. $n you need write to a regular variable to use the substitution 请不要忘记，如果它的变量$ 1 .. $ n你需要写一个常规变量来使用替换

#!/bin/bash
NOW=$1
echo  ${NOW:-$(date +"%Y-%m-%d")}

#3楼

You can set a default value for a variable like so: 您可以为变量设置默认值，如下所示：

somecommand.sh somecommand.sh

#!/usr/bin/env bash

ARG1=${1:-foo}
ARG2=${2:-bar}
ARG3=${3:-1}
ARG4=${4:-$(date)}

echo "$ARG1"
echo "$ARG2"
echo "$ARG3"
echo "$ARG4"

Here are some examples of how this works: 以下是一些如何工作的示例：

$ ./somecommand.sh
foo
bar
1
Thu Mar 29 10:03:20 ADT 2018

$ ./somecommand.sh ez
ez
bar
1
Thu Mar 29 10:03:40 ADT 2018

$ ./somecommand.sh able was i
able
was
i
Thu Mar 29 10:03:54 ADT 2018

$ ./somecommand.sh "able was i"
able was i
bar
1
Thu Mar 29 10:04:01 ADT 2018

$ ./somecommand.sh "able was i" super
able was i
super
1
Thu Mar 29 10:04:10 ADT 2018

$ ./somecommand.sh "" "super duper"
foo
super duper
1
Thu Mar 29 10:05:04 ADT 2018

$ ./somecommand.sh "" "super duper" hi you
foo
super duper
hi
you

#4楼

For optional multiple arguments, by analogy with the ls command which can take one or more files or by default lists everything in the current directory: 对于可选的多个参数，可以通过类似于ls命令来获取一个或多个文件，或者默认列出当前目录中的所有内容：

if [ $# -ge 1 ]
then
    files="$@"
else
    files=*
fi
for f in $files
do
    echo "found $f"
done

Does not work correctly for files with spaces in the path, alas. 对于路径中包含空格的文件，它无法正常工作，唉。 Have not figured out how to make that work yet. 还没弄明白如何做到这一点。

#5楼

It's possible to use variable substitution to substitute a fixed value or a command (like date ) for an argument. 可以使用变量替换来替换参数的固定值或命令（如date ）。 The answers so far have focused on fixed values, but this is what I used to make date an optional argument: 到目前为止，答案都集中在固定值上，但这是我过去将日期作为可选参数的原因：

~$ sh co.sh
2017-01-05

~$ sh co.sh 2017-01-04
2017-01-04

~$ cat co.sh

DAY=${1:-$(date +%F -d "yesterday")}
echo $DAY

#6楼

This allows default value for optional 1st arg, and preserves multiple args. 这允许可选1st arg的默认值，并保留多个args。

 > cat mosh.sh
   set -- ${1:-xyz} ${@:2:$#} ; echo $*    
 > mosh.sh
   xyz
 > mosh.sh  1 2 3
   1 2 3