如何删除Powershell中的第一行和最后一行

Question

This script will do some processing on csv file notably removing first line (subsequent to How to export to "non-standard" CSV with Powershell ) :

Import-Csv in.csv -header Date,Time,O,H,L,C,V|select * -ExcludeProperty time|
%{$_.date = [datetime]::ParseExact($_.date,"yyyy.MM.dd",$null).tostring("yyMMdd");$_.v=1;$_}|
ConvertTo-Csv -NoTypeInformation|
select -skip 1|
%{$_ -replace '"'}|
Set-Content out.csv -encoding ascii

Now I need to refine it by also removing last line. I tried to add :

select -skip ($_.Count - 1)

but it generates exception.

So what the right syntax ?

Answer 1

Depending on the version of PowerShell you have, you can use the -SkipLast parameter, eg:

... | Select -Skip 1 | Select -SkipLast 1

SkipLast is available for PowerShell 5.0 and higher.

If you don't have that parameter, you can install it via the Microsoft Website. Windows 7 is the earliest OS version that can run PowerShell 5.

If that's not possible, use:

$csv = Import-Csv in.csv -header Date,Time,O,H,L,C,V | `
       Select * -ExcludeProperty time | `
       Foreach {$_.date = [datetime]::ParseExact($_.date,"yyyy.MM.dd",$null).tostring("yyMMdd");$_.v=1;$_} | `
       ConvertTo-Csv -NoTypeInformation

for ($i = 1; $i -lt ($csv.Length - 1); $i++) { 
    $csv[$i] -replace '"' | Add-Content out.csv -encoding ascii
}

Answer 2

If you cannot run -SkipLast because you don't have Powershell 5, rather than using a for loop, I would suggest using this :

$csv[1..$($csv.Count - 2)]

This way, you will skip the first and last line. Then, you must do some checks on your $csv variable (length, etc.) add your set-content code, and it should work fine.