Here is myscript.sh
这是myscript.sh
#!/bin/bash
for i in {1..
Here is myscript.sh
这是myscript.sh
#!/bin/bash
for i in {1..$1};
do
echo $1 $i;
done
If I run myscript.sh 3 the output is
如果我myscript运行。输出是。
3 {1..3}
instead of
而不是
3 1
3 2
3 3
Clearly $3 contains the right value, so why doesn't for i in {1..$1} behave the same as if I had written for i in {1..3} directly?
显然$3包含正确的值，所以为什么不在{1}中为i。$1}的行为与我在{1}中为I所写的一样。直接3 } ?
5 个解决方案
#1
50
You should use a C-style for loop to accomplish this:
您应该使用C-style for循环来实现以下目标:
for ((i=1; i<=$1; i++)); do
echo $i
done
This avoids external commands and nasty eval statements.
这避免了外部命令和讨厌的eval语句。
#2
23
Because brace expansion occurs before expansion of variables. https://www.gnu.org/software/bash/manual/bashref.html#Brace-Expansion.
因为支撑展开发生在变量展开之前。https://www.gnu.org/software/bash/manual/bashref.html Brace-Expansion。
If you want to use braces, you could so something grim like this:
如果你想用牙套，你可以做一些像这样可怕的事情:
for i in `eval echo {1..$1}`;
do
echo $1 $i;
done
Summary: Bash is vile.
摘要:Bash是可耻的。
#3
11
You can use seq command:
您可以使用seq命令:
for i in `seq 1 $1`
Or you can use the C-style for...loop:
或者你也可以使用C-style for…
for((i=1;i<=$1;i++))
#4
1
I know you've mentioned bash in the heading, but I would add that 'for i in {$1..$2}' works as intended in zsh. If your system has zsh installed, you can just change your shebang to zsh.
我知道你在标题中提到了bash，但是我要在{$1}中加上它。$2}在zsh中的工作。如果您的系统已经安装了zsh，您可以将shebang更改为zsh。
Using zsh with the example 'for i in {$1..$2}' also has the added benefit that $1 can be less than $2 and it still works, something that would require quite a bit of messing about if you wanted that kind of flexibility with a C-style for loop.
使用zsh和示例“for i in{$1..”$2}也有额外的好处，1美元可以少于2美元，而且它仍然有效，如果你想要那种带有c型循环的灵活性，那就需要相当多的麻烦。
#5
1
Here is a way to expand variables inside braces without eval:
这里有一种方法可以在不使用eval的括号内展开变量:
end=3
declare -a 'range=({'"1..$end"'})'
We now have a nice array of numbers:
我们现在有了一个漂亮的数字数组:
for i in ${range[@]};do echo $i;done
1
2
3
};
do
echo
Here is myscript.sh
这是myscript.sh
#!/bin/bash
for i in {1..$1};
do
echo $1 $i;
done
If I run myscript.sh 3 the output is
如果我myscript运行。输出是。
3 {1..3}
instead of
而不是
3 1
3 2
3 3
Clearly $3 contains the right value, so why doesn't for i in {1..$1} behave the same as if I had written for i in {1..3} directly?
显然$3包含正确的值，所以为什么不在{1}中为i。$1}的行为与我在{1}中为I所写的一样。直接3 } ?
5 个解决方案
#1
50
You should use a C-style for loop to accomplish this:
您应该使用C-style for循环来实现以下目标:
for ((i=1; i<=$1; i++)); do
echo $i
done
This avoids external commands and nasty eval statements.
这避免了外部命令和讨厌的eval语句。
#2
23
Because brace expansion occurs before expansion of variables. https://www.gnu.org/software/bash/manual/bashref.html#Brace-Expansion.
因为支撑展开发生在变量展开之前。https://www.gnu.org/software/bash/manual/bashref.html Brace-Expansion。
If you want to use braces, you could so something grim like this:
如果你想用牙套，你可以做一些像这样可怕的事情:
for i in `eval echo {1..$1}`;
do
echo $1 $i;
done
Summary: Bash is vile.
摘要:Bash是可耻的。
#3
11
You can use seq command:
您可以使用seq命令:
for i in `seq 1 $1`
Or you can use the C-style for...loop:
或者你也可以使用C-style for…
for((i=1;i<=$1;i++))
#4
1
I know you've mentioned bash in the heading, but I would add that 'for i in {$1..$2}' works as intended in zsh. If your system has zsh installed, you can just change your shebang to zsh.
我知道你在标题中提到了bash，但是我要在{$1}中加上它。$2}在zsh中的工作。如果您的系统已经安装了zsh，您可以将shebang更改为zsh。
Using zsh with the example 'for i in {$1..$2}' also has the added benefit that $1 can be less than $2 and it still works, something that would require quite a bit of messing about if you wanted that kind of flexibility with a C-style for loop.
使用zsh和示例“for i in{$1..”$2}也有额外的好处，1美元可以少于2美元，而且它仍然有效，如果你想要那种带有c型循环的灵活性，那就需要相当多的麻烦。
#5
1
Here is a way to expand variables inside braces without eval:
这里有一种方法可以在不使用eval的括号内展开变量:
end=3
declare -a 'range=({'"1..$end"'})'
We now have a nice array of numbers:
我们现在有了一个漂亮的数字数组:
for i in ${range[@]};do echo $i;done
1
2
3
$i;
done
#!/bin/ba
