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#PSTip Reading file content as a byte array

Note: This tip requires PowerShell 2.0 or above.

A few days ago I had to write a script to upload files to a remote FTP server. I needed to read the file (0.7 mb) and store it as a byte array. My first attempt to do this was to use the Get-Content cmdlet.

Get-Content c:\test.log -Encoding Byte

It works great but there’s only one downside to it–it is painfully slow–and I quickly resorted to an alternative method using a .NET class:

[System.IO.File]::ReadAllBytes('c:\test.log')

ReadAllBytes() worked incredibly fast in compare to the cmdlet. I measured how much it took for each command to finish. Get-Content took 18.308045 seconds to complete while ReadAllBytes() took only 0.2811065!

I had a time limit to finish the script so I left it with the .NET method and decided to check later what can be done to make Get-Content perform faster. Later on I came back to it and checked the help of Get-Content. The answer was found in the ReadCount parameter. The default behavior is sending one line at a time, in my case it was one byte at a time.

PS> Get-Help Get-Content -Parameter ReadCount

-ReadCount
    Specifies how many lines of content are sent through the pipeline at a time. The default value is 1. A value of 0
    (zero) sends all of the content at one time.

    This parameter does not change the content displayed, but it does affect the time it takes to display the content.
    As the value of ReadCount increases, the time it takes to return the first line increases, but the total time for
    the operation decreases. This can make a perceptible difference in very large items.

    Required?                    false
    Position?                    named
    Default value                1
    Accept pipeline input?       true (ByPropertyName)
    Accept wildcard characters?  false

I changed it to 0 so all content can be read in a single operation and then I measured again its execution time.

Get-Content c:\test.log -Encoding Byte -ReadCount 0

At first glance the result looked very similar to the .NET method, but to my big surprise, it was even faster to complete–only 0.2384541 seconds!

Filed in: Columns, Tips and Tricks Tags: , , ,

4 Responses to "#PSTip Reading file content as a byte array"

  1. Violetta says:

    Grate!!!

    Thank you!

  2. Thomas says:

    Thank you — this was incredibly helpful!

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