{"id":15781,"date":"2011-01-27T00:01:00","date_gmt":"2011-01-27T00:01:00","guid":{"rendered":"https:\/\/blogs.technet.microsoft.com\/heyscriptingguy\/2011\/01\/27\/use-powershell-to-toggle-the-archive-bit-on-files\/"},"modified":"2011-01-27T00:01:00","modified_gmt":"2011-01-27T00:01:00","slug":"use-powershell-to-toggle-the-archive-bit-on-files","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/scripting\/use-powershell-to-toggle-the-archive-bit-on-files\/","title":{"rendered":"Use PowerShell to Toggle the Archive Bit on Files"},"content":{"rendered":"

 <\/p>\n

Summary<\/b>: Learn how to use Windows PowerShell to toggle file attributes such as the archive bit.<\/p>\n

\"Hey, Hey, Scripting Guy! I have a number of files that have had the archive bit flipped. Unfortunately, our backup program relies on the archive bit to determine if it has backed up a file recently or if a file has changed and is in need of backup again. What I need is a way to flip all of the archive bits in a folder. <\/p>\n

— BW<\/p>\n

\"Hey, Hello BW, <\/p>\n

Microsoft Scripting Guy Ed Wilson here. Backup programs. Hmmm, I used to know a person who claimed he had an ideal business model. He said he would advertise extremely low-cost backup tape storage. The backup tapes would be stored in a big hole in the ground. When someone requested a tape from \u201cstorage,\u201d they would be given a blank tape. This model would work, he said, because no one ever tests backup tapes, and no one ever practices a file restore. Luckily, this person never went into business, and never implemented the \u201clow-cost storage\u201d solution. <\/p>\n

BW, I have seen the problem you mention occur when someone runs a scheduled daily backup to perform a custom ad hoc backup, instead of creating a custom on-demand job that does not flip archive bits. When this happens, backups get out of sequence, and it can be a real mess. <\/p>\n

\n

In yesterday\u2019s Hey, Scripting Guy! Blog post<\/a>, I began a discussion of using the Set-ItemProperty<\/b> Windows PowerShell cmdlet to work with archive bits on a file. <\/p>\n<\/blockquote>\n

The FSO library on my laptop contains a mixture of files. Some have the archive bit set and others do not. Some are compressed, others encrypted, and still others read-only. The folder is shown in the following image.<\/p>\n

\"Image<\/a><\/p>\n

The Get-FilesWithArchiveBitSet.ps1 script will go through a folder and report files that have the archive bit set. It does not matter if there are additional file attributes; the script will detect the presence of the archive bit. The use of the io.fileattributes<\/b> enumeration was discussed in yesterday\u2019s Hey, Scripting Guy! Blog post. <\/p>\n

The key to the script is the use of the If<\/b> statement to perform a bitwise AND operation on the file attributes:<\/p>\n

\n

If((Get-ItemProperty -Path $file.fullname).attributes -band $attribute)<\/font><\/font><\/span><\/p>\n<\/blockquote>\n

If the attribute is present, it is reported in green. If the attribute is not present, it is reported in blue:<\/p>\n

\n

{ Write-Host -ForegroundColor green `<\/font><\/font><\/span><\/p>\n

    <\/font><\/span>"$file.fullname has the $attribute bit set" }<\/font><\/font><\/font><\/span><\/p>\n

 <\/font><\/span>ELSE<\/font><\/font><\/font><\/span><\/p>\n

  <\/font><\/span>{ Write-host -ForegroundColor blue `<\/font><\/font><\/font><\/span><\/p>\n

    <\/font><\/span>"$file.fullname does not have the $attribute bit set"}<\/font><\/font><\/font><\/span><\/p><\/blockquote>\n

The complete script is shown here.<\/p>\n

\n

Get-FilesWithArchiveBitSet.ps1<\/font><\/font><\/span><\/p>\n

$path = "C:\\fso"<\/font><\/font><\/span><\/p>\n

$files = Get-ChildItem -Path $path -Recurse<\/font><\/font><\/span><\/p>\n

$attribute = [io.fileattributes]::archive<\/font><\/font><\/span><\/p>\n

 <\/font><\/font><\/span><\/p>\n

Foreach($file in $files)<\/font><\/font><\/span><\/p>\n

{<\/font><\/font><\/span><\/p>\n

 <\/font><\/span>If((Get-ItemProperty -Path $file.fullname).attributes -band $attribute)<\/font><\/font><\/font><\/span><\/p>\n

  <\/font><\/span>{ Write-Host -ForegroundColor green `<\/font><\/font><\/font><\/span><\/p>\n

    <\/font><\/span>"$file.fullname has the $attribute bit set" }<\/font><\/font><\/font><\/span><\/p>\n

 <\/font><\/span>ELSE<\/font><\/font><\/font><\/span><\/p>\n

  <\/font><\/span>{ Write-host -ForegroundColor blue `<\/font><\/font><\/font><\/span><\/p>\n

    <\/font><\/span>"$file.fullname does not have the $attribute bit set"}<\/font><\/font><\/font><\/span><\/p>\n

} #end Foreach<\/font><\/font><\/span><\/p><\/blockquote>\n

When the Get-FilesWithArchiveBitSet.ps1 script runs, the output appears that is shown in the following image:<\/p>\n

Now that we understand the basic process, let\u2019s add one additional concept. To toggle the archive bit, I need to use a Bitwise Exclusive Or (BXOR) operator. <\/p>\n

In the table that appears here, the first row is the decimal value of the position. In the second row is the binary representation of the number 33 that I obtained by using the convert<\/b> class. In the second row, notice there is a 1 in the 32 column, and a 1 in the 1 column. The third row is the binary value of the number 1 (the value of the read-only enumeration). The fourth row represents the results of performing a bitwise Exclusive OR (BXOR) operation. When performing a BXOR operation, the rules are thus: <\/p>\n

1 \u2013BXOR 1 = 0, 1 \u2013BXOR 0 = 1, 0 \u2013BXOR 0 = 0. <\/p>\n\n\n\n\n\n\n
\n

128<\/p>\n<\/td>\n

\n

64<\/p>\n<\/td>\n

\n

32<\/p>\n<\/td>\n

\n

16<\/p>\n<\/td>\n

\n

8<\/p>\n<\/td>\n

\n

4<\/p>\n<\/td>\n

\n

2<\/p>\n<\/td>\n

\n

1<\/p>\n<\/td>\n<\/tr>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

1<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

1<\/p>\n<\/td>\n<\/tr>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

1<\/p>\n<\/td>\n<\/tr>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

1<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

I can use this information to determine the attributes other than the archive bit of a file. This is illustrated here. Notice that when I use \u2013bxor<\/b> on the file attributes, and \u2013bxor<\/b> with the archive bit, what remains is the ReadOnly<\/b> attribute. <\/p>\n

\n

PS C:\\> (Get-ItemProperty C:\\fso\\a.txt).attributes<\/font><\/font><\/span><\/p>\n

ReadOnly, Archive<\/font><\/font><\/span><\/p>\n

PS C:\\> (Get-ItemProperty C:\\fso\\a.txt).attributes -bxor [io.fileattributes]::Archive<\/font><\/font><\/span><\/p>\n

1<\/font><\/font><\/span><\/p>\n

PS C:\\><\/font><\/font><\/span><\/span><\/p>\n<\/blockquote>\n

Armed with this information, I create a script that will toggle the archive bit of a file. If the archive bit exists, it is removed; if it does not exist, it is added to the file. The Set-FilesWithArchiveBit.ps1 script is shown here.<\/p>\n

\n

Set-FilesWithArchiveBit.ps1<\/font><\/font><\/span><\/p>\n

$path = "C:\\fso"<\/font><\/font><\/span><\/p>\n

$files = Get-ChildItem -Path $path -Recurse<\/font><\/font><\/span><\/p>\n

$attribute = [io.fileattributes]::archive<\/font><\/font><\/span><\/p>\n

 <\/font><\/font><\/span><\/p>\n

Foreach($file in $files)<\/font><\/font><\/span><\/p>\n

{<\/font><\/font><\/span><\/p>\n

 <\/font><\/span>If((Get-ItemProperty -Path $file.fullname).attributes -band $attribute)<\/font><\/font><\/font><\/span><\/p>\n

  <\/font><\/span>{ <\/font><\/font><\/font><\/span><\/p>\n

   <\/font><\/span>"$file.fullname has the $attribute bit set, removing the bit."<\/font><\/font><\/font><\/span><\/p>\n

   <\/font><\/span>Set-ItemProperty -Path $file.fullname -Name attributes `<\/font><\/font><\/font><\/span><\/p>\n

     <\/font><\/span>-Value ((Get-ItemProperty $file.fullname).attributes -BXOR $attribute)<\/font><\/font><\/font><\/span><\/p>\n

   <\/font><\/span>"New value of $file.Fullname attributes"<\/font><\/font><\/font><\/span><\/p>\n

   <\/font><\/span>(Get-ItemProperty -Path $file.fullname).attributes<\/font><\/font><\/font><\/span><\/p>\n

  <\/font><\/span>}<\/font><\/font><\/font><\/span><\/p>\n

 <\/font><\/span>ELSE<\/font><\/font><\/font><\/span><\/p>\n

  <\/font><\/span>{ <\/font><\/font><\/font><\/span><\/p>\n

    <\/font><\/span>Write-host -ForegroundColor blue `<\/font><\/font><\/font><\/span><\/p>\n

    <\/font><\/span>"$file.fullname does not have the $attribute bit set, setting the bit."<\/font><\/font><\/font><\/span><\/p>\n

    <\/font><\/span>Set-ItemProperty -Path $file.fullname -Name attributes `<\/font><\/font><\/font><\/span><\/p>\n

      <\/font><\/span>-Value ((Get-ItemProperty $file.fullname).attributes -BXOR $attribute)<\/font><\/font><\/font><\/span><\/p>\n

    <\/font><\/span>"New value of $file.Fullname attributes"<\/font><\/font><\/font><\/span><\/p>\n

   <\/font><\/span>(Get-ItemProperty -Path $file.fullname).attributes<\/font><\/font><\/font><\/span><\/p>\n

    <\/font><\/span>}<\/font><\/font><\/font><\/span><\/p>\n

} #end Foreach<\/font><\/font><\/span><\/p><\/blockquote>\n

The Set-FilesWithArchiveBit.ps1 script is similar to the earlier script except that the Set-ItemProperty<\/b> Windows PowerShell cmdlet is used to change the value of the attributes of the file. To do this, I use Get-ItemProperty<\/b> to retrieve the file attributes, and then I use BXOR to perform a bitwise exclusive OR operation with my chosen attribute. This portion of the code is shown here:<\/p>\n

\n

Set-ItemProperty -Path $file.fullname -Name attributes `<\/font><\/font><\/span><\/p>\n

     <\/font><\/span>-Value ((Get-ItemProperty $file.fullname).attributes -BXOR $attribute)<\/font><\/font><\/font><\/span><\/p>\n<\/blockquote>\n

When the Set-FilesWithArchiveBit.ps1 script runs, the output appears that is shown in the following image:<\/p>\n

\"Image<\/a><\/p>\n

One thing to keep in mind about using the Set-ItemProperty<\/b> cmdlet to work with file attributes through the FileSystem<\/b> provider is that it is limited to working with the following attributes: Archive<\/b>, Hidden<\/b>, Normal<\/b>, ReadOnly<\/b>, or System<\/b>. An error will be generated, and the attributes will not be modified if a file is compressed or encrypted.<\/p>\n

BW, that is all there is to using the Set-ItemProperty<\/b> cmdlet to toggle the archive bit. <\/p>\n

I invite you to follow me on Twitter<\/a> and Facebook<\/a>. If you have any questions, send email to me at scripter@microsoft.com<\/a>, or post your questions on the Official Scripting Guys Forum<\/a>. See you tomorrow. Until then, peace.<\/p>\n

 <\/p>\n

Ed Wilson, Microsoft Scripting Guy<\/b><\/p>\n","protected":false},"excerpt":{"rendered":"

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\"Image<\/a><\/p>\n