Bash Shell 脚本：使用 Diff 命令
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Bash Shell Script: Using Diff command
提问by Gabriel
Can anyone help me out to figuring what is wrong with this program?
谁能帮我弄清楚这个程序有什么问题？
#!/bin/bash
find teste1 > names.lst
find teste2 > names2.lst
result=$(diff -y -W 72 $names $names2)
if [ $? -eq 0]; then
echo "files are the same"
else
echo "files are different"
echo "$result"
fi
It returns the following errors:
它返回以下错误：
diff: missing operand
差异：缺少操作数
teste.sh: [: missing ']'
teste.sh: [: 缺少 ']'
Files are different
文件不一样
(a blank space appears here)
（此处出现空格）
The blank space is the variable "result" but why did it not save the differences between the 2 files?
空格是变量“结果”，但为什么不保存两个文件之间的差异？
I am trying to use diff to find out the differences in the texts on both those files.
我正在尝试使用 diff 找出这两个文件中文本的差异。
回答by Raman Shah
In addition to diffing undefined variables $names and $names2 instead of the files you created (names.lst and names2.lst), there is a couple of syntax error: you need a space around square brackets to execute the conditional.
除了区分未定义的变量 $names 和 $names2 而不是您创建的文件（names.lst 和 names2.lst）之外，还有一些语法错误：您需要在方括号周围留一个空格来执行条件。
#! /bin/bash
find teste1 > names.lst
find teste1 > names2.lst
result=$(diff -y -W 72 names.lst names2.lst)
if [ $? -eq 0 ]
then
echo "files are the same"
else
echo "files are different"
echo "$result"
fi
回答by F. Hauri
There is some little errors...
有一些小错误...
teste.sh: [: missing ']': you miss a space after0variables
$nameand$name2seem not populated.
teste.sh: [: missing ']': 你错过了一个空格0变量
$name，$name2似乎没有填充。
And some improvement could be:
一些改进可能是：
But doing this under recent bash don't require to write a script:
但是在最近的 bash 下执行此操作不需要编写脚本：
result="$(diff -y <(find teste1) <(find teste2))" &&
echo files are the same ||
{ echo files differ; echo $result; }
or
或者
result="$(diff -y <(find teste1) <(find teste2))" &&
echo files are the same || printf "files differ:\n%s" "$result"
One of the main advantage of this is that there is no need of temporary files.
这样做的主要优点之一是不需要临时文件。
Of course this could be written properlyand more readable:
这当然可以写正确，更具可读性：
#!/bin/bash
files=(
"/path1/teste 1"
"/path2/teste 2"
)
if result="$(
diff -y -W78 <(
find ${files[0]}
) <(
find ${files[1]}
) )"
then
echo "Files are the sames"
else
echo "Files are differents"
echo "$result"
fi
