以相反的顺序打印 bash 参数
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Print bash arguments in reverse order
提问by Morten Telling
I have to write a script, which will take all arguments and print them in reverse.
我必须编写一个脚本，它将接受所有参数并反向打印它们。
I've made a solution, but find it very bad. Do you have a smarter idea?
我已经做了一个解决方案，但发现它很糟糕。你有更聪明的想法吗？
#!/bin/sh
> tekst.txt
for i in $*
do
echo $i | cat - tekst.txt > temp && mv temp tekst.txt
done
cat tekst.txt
回答by 123
Could do this
可以这样做
for (( i=$#;i>0;i-- ));do
echo "${!i}"
done
This uses the below
c style for loop
Parameter indirect expansion(${!i}towards the bottom of the page)
这使用以下
c 样式的循环
参数间接扩展（${!i}朝向页面底部）
And $#which is the number of arguments to the script
而$#这是脚本变量的数量
回答by Mohammad Razeghi
you can use this one liner:
你可以使用这个衬垫：
echo $@ | tr ' ' '\n' | tac | tr '\n' ' '
回答by Isaac
Portably and POSIXly, without arrays and working with spaces and newlines:
便携和 POSIXly，没有数组并使用空格和换行符：
Reverse the positional parameters:
反转位置参数：
flag=''; c=1; for a in "$@"; do set -- "$a" ${flag-"$@"}; unset flag; done
Print them:
打印它们：
printf '<%s>' "$@"; echo
回答by Vrata Blazek
bash:
重击：
#!/bin/bash
for i in "$@"; do
echo "$i"
done | tac
call this script like:
将此脚本称为：
./reverse 1 2 3 4
it will print:
它会打印：
4
3
2
1
回答by F. Hauri
Reversing a simple string, by spaces
用空格反转一个简单的字符串
Simply:
简单地：
#!/bin/sh
o=
for i;do
o="$i $o"
done
echo "$o"
will work as
将作为
./rev.sh 1 2 3 4
4 3 2 1
Or
或者
./rev.sh world! Hello
Hello world!
If you need to output one line by argument
如果需要逐行输出
Just replace echoby printf "%s\n":
只需替换echo为printf "%s\n"：
#!/bin/sh
o=
for i;do
o="$i $o"
done
printf "%s\n" $o
Reversing an array of strings
反转字符串数组
If your argument could contain spaces, you could use bash arrays:
如果您的参数可能包含空格，则可以使用 bash 数组：
#!/bin/bash
declare -a o=()
for i;do
o=("$i" "${o[@]}")
done
printf "%s\n" "${o[@]}"
Sample:
样本：
./rev.sh "Hello world" print will this
this
will
print
Hello world
