Using get-content to rename a folder?

Question

I am attempting to rename a folder based on the first 10 characters inside a file using a powershell command.

I got as far as far as pulling the data I need to use to rename but I don't know how to pass it.

Get-Content 'C:\DATA\Company.dat' |
    Select-Object -first 10 |
    rename 'C:\DATA\FOLDER' 'C:\DATA\FOLDER (first 10)'

the part I'm stuck on is (first 10), I don't know what to pass to that section to complete my task?

score 3 · Accepted Answer · edited Apr 18 '19 at 14:02

3

Select-Object -first 10 will take the first 10 objects. In your case this will be the first 10 lines of the file, not 10 characters.

You can use something like this

Rename-Item -Path 'C:\DATA\FOLDER' -NewName "C:\DATA\$((Get-Content 'C:\DATA\Company.dat' | Select-Object -first 1).Substring(0,10))"

Using -first 1 to get the first line and .Substring(0,10) to get the first 10 characters.

Edit: Or as @AdminOfThings mentioned, without the Select-Object

Rename-Item -Path 'C:\DATA\FOLDER' -NewName "C:\DATA\$((Get-Content 'C:\DATA\Company.dat' -raw).Substring(0,10))"

edited Apr 18 '19 at 14:02

mklement0

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answered Apr 18 '19 at 13:07

Michael B.

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If you want to avoid piping to `Select`, you can use the `-Raw` switch on `Get-Content`. – AdminOfThings Apr 18 '19 at 13:10
This worked for what I needed to do. Thank you very much. – astanix Apr 18 '19 at 13:32

mklement0 · Answer 2 · 2019-04-18T15:09:07.073

To complement Michael B.'s helpful answer with a 3rd approach:

If the characters of interest are known to be all on the 1st line (which is a safe assumption in your case), you can use Get-Content -First 1 ... (same as: Get-Content -TotalCount 1 ...) to retrieve that 1st line directly (and exclusively), which:

performs better than Get-Content ... | Select-Object -First 1
avoids having to read the entire file into memory with Get-Content -Raw ...

 Rename-Item 'C:\DATA\FOLDER' `
             "FOLDER $((Get-Content -First 1 C:\DATA\Company.dat).Substring(0, 10))"

Note:

It is sufficient to pass only the new name to Rename-Item's 2nd positional argument (the -NewName parameter); e.g., FOLDER 1234567890, not the whole path. While you can pass the whole path, it must refer to the same location as the input path.
The substring-extraction command is embedded inside an expandable string ("...") by way of $(...) the subexpression operator.

As for what you tried:

Select-Object -First 10 gets the first 10 input objects, which are the file's lines output by Get-Content; in other words: you'll send 10 lines rather than 10 characters through the pipeline, and even if they were characters, they'd be sent one by one.

While it is possible to solve this problem in the pipeline, it would be cumbersome and slow:

-join ( # -join, given an array of chars., returns a string
  Get-Content -First 1 C:\DATA\Company.dat | # get 1st line
    ForEach-Object ToCharArray |  # convert to a char. array
      Select-Object -First 10 # get first 10 chars.
) | 
  Rename-Item 'C:\DATA\FOLDER' { 'FOLDER ' + $_ }

That said, you could transform the above into something faster and more concise:

-join (Get-Content -First 1 C:\DATA\Company.dat)[0..9] |
  Rename-Item 'C:\DATA\FOLDER' { 'FOLDER ' + $_ }

Note:

Get-Content -First 1 returns (at most) 1 line, in which case PowerShell returns that line as-is, not wrapped in an array.
Indexing into a string ([...]) with the range operator (..') - e.g., [0..9] - implicitly extracts the characters at the specified positions as an array; it is as if you had called .ToCharArray()[0..9]
Note how the new name is determined via a delay-bind script-block argument ({ ... }) in which $_ refers to the input object (the 10-character string, in this case); it is this technique that enables a renaming command to operate on multiple inputs, where each new name is derived from the specific input at hand.

Using get-content to rename a folder?

2 Answers2