我不确定您的输入内容或匹配要求，但是您可以轻松地使用Linq或 for 循环下面是两个简单的示例，它们读取输入文件 sample.txt 并写入输出文件 out.csv 。

使用Linq：

  string periodValue = 201410; 
 File.WriteAllLines（
 out.txt，
 File.ReadAllLines（ sample.txt）。
 Select（l = > l.Replace（ Attend_10， Attend_10_ + periodValue））
）; 
 

使用 for 循环：

  string periodValue = 201410; 
字符串[] l ines = File.ReadAllLines（ sample.txt）; 
 for（int i = 0; i< lines.Length; i ++）
 {
 lines [i] = lines [i] .Replace（ Attend_10， Attend_10_ + periodValue ）; 
} 
 File.WriteAllLines（ out.txt，行）; 
 

输入：sample.txt：

 < SomeTextHere> 
<文件名> = Attend_10 
< MoreTextHere> 
 

输出：out.txt

 < SomeTextHere> 
<文件名> = Attend_10_201410 
< MoreTextHere> 
 

如果您的匹配要求更高级，则可以使用RegEx来匹配每个字符串中的某些模式。 / p>

How can i read a certain portion of a text file and replace with another line?

Like in the file there is a part :"Attend_10" want to replace it with "Attend_10_[Variable_Value].

How can i Do this using script (C#) in SSIS?

I'm not sure exactly what your inputs are, or requirements for matching, but you could easily use Linq or a for loop to perform this. Below are two simple examples that read an input file sample.txt and write to an output file out.csv.

Using Linq:

string periodValue = "201410";
File.WriteAllLines(
    "out.txt",
    File.ReadAllLines("sample.txt").
        Select(l => l.Replace("Attend_10", "Attend_10_" + periodValue))
    );

Using a for loop:

string periodValue = "201410";
string[] lines = File.ReadAllLines("sample.txt");
for (int i = 0; i < lines.Length; i++)
{
    lines[i] = lines[i].Replace("Attend_10", "Attend_10_" + periodValue);
}
File.WriteAllLines("out.txt", lines);

Input: sample.txt:

<SomeTextHere>
<File Name>=Attend_10
<MoreTextHere>

Output: out.txt

<SomeTextHere>
<File Name>=Attend_10_201410
<MoreTextHere>

If your matching requirements are more advanced, you can use RegEx to match certain patterns in each string.