如何在Powershell脚本中匹配文本文件内容的每一行

Question

I have a text file 'abc.txt' that contains the below.
hello_1
hello_2
..
..
hello_n

I need to write a script to open the file abc.txt and read each line and store that each line in a variable called $temp. I need to read the line only that starts with 'hello'. What is wrong with the below code?
I have the below Code:

foreach ($line in Get-Content "c:\folder\abc.txt")    
{    
    if($line Select-String -Pattern 'hello')
    $temp=$line
}

Answer 1

You missing pipeline after $line , and curly braces are missing in the whole scriptblock { and } after the foreach , should be:

foreach ($line in Get-Content "c:\folder\abc.txt")    
{    
    {
    if($line | Select-String -Pattern 'hello')
    $temp=$line
    }
}

Also, I don't know what is your purpose, but if you want $line will not be overwrited each time you should create an array outside of the iterration and fill it each time:

so first is: $line = @() and instead of $temp=$line change to $temp += $line

But then again if all your purpose is to filter the hello string from the text file then this should be enough:

$temp = (Get-Content "c:\folder\abc.txt") -match '^hello'

Answer 2

Try this -

$temp = @()
(Get-Content "c:\folder\abc.txt") | % {$temp += $_ | Select-String -Pattern "hello"}
$temp

The code is getting the content of abc.txt , and for each object checking if the pattern matches hello . If it's a match, then it stores the corresponding value in the array defined as $temp .

OR

You can rephrase your original code like this -

$temp = @()
foreach ($line in Get-Content "c:\folder\abc.txt")    
{    
    if($line | Select-String -Pattern 'hello') {
    $temp += line
    }
}

In you original code, you are missing a pipeline in the statement if($line Select-String -Pattern 'hello') . And you are missing braces {} to enclose the if statement.