Linux 算术表达式：期待 EOF：“008 +1”
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arithmetic expression: expecting EOF: "008 +1"
提问by craphunter
My script ./make_shift_ln_o_dummy.sh:
我的脚本 ./make_shift_ln_o_dummy.sh：
for i in `seq -w 0 272`
do
y=0
x=1
echo $i
y=$(($i +$x))
echo $y
done
My output with error message: arithmetic expression: expecting EOF: "008 +1"
我的错误信息输出：算术表达式：期待 EOF：“008 +1”
000
1
001
2
002
3
003
4
004
5
005
6
006
7
007
8
008
./make_shift_ln_o_dummy.sh: 25: arithmetic expression: expecting EOF: "008 +1"
Why does it happen? What do I do wrong? How should I change it to the output of 272?
为什么会发生？我做错了什么？我应该如何将其更改为 272 的输出？
回答by anubhava
No need to use seqhere. You can use bash arithmetic features like this:
seq这里不需要使用。您可以像这样使用 bash 算术功能：
for ((i=0; i<272; i++))
do
y=0
x=1
printf "%03d\n" $i
y=$(($i + $x))
printf "%03d\n" $y
done
回答by msw
Why does it happen?
为什么会发生？
The bash expression evaluator sees the leading 0and assumes that an octal constant is going to follow but 8is not a valid octal digit.
bash 表达式计算器看到前导0并假设8后面跟着一个八进制常量，但不是一个有效的八进制数字。
Version 4.2 of bashgives a more helpful diagnostic:
的 4.2 版bash提供了更有用的诊断：
$ echo $((007 + 1))
8
$ echo $((008 + 1))
bash: 008: value too great for base (error token is "008")
The answer from anubhavaabove gave the "how to fix" which is why I upvoted it.
上面来自 anubhava的答案给出了“如何修复”，这就是我赞成它的原因。
回答by glenn Hymanman
008 is an octal number. You can specify you want to use a base-10 number in your arithmetic expression:
008 是八进制数。您可以指定要在算术表达式中使用以 10 为基数的数字：
y=$((10#$i +$x))
http://www.gnu.org/software/bash/manual/bashref.html#Shell-Arithmetic
http://www.gnu.org/software/bash/manual/bashref.html#Shell-Arithmetic
