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How To: How and when to use CheckSum (MD5)

Summary

What is CheckSum?

A checksum is a string of numbers and letters used to uniquely identify a file. Checksum is most commonly used to verify if a copy of a file is identical to an original, such as downloaded copies of ArcGIS product installation or patch files.

How does CheckSum work?

A file is pushed through an algorithm, which outputs a unique alphanumeric string called a checksum, also known as a "hash". Different files, even those with minute differences, produce different checksum values.
There are multiple algorithms that can be used to produce a checksum value. The algorithm that Esri uses to provide checksum values is MD5. Other algorithms include SHA-1, SHA-256, and SHA-512.

What circumstances would warrant verifying a CheckSum value?

Files may be changed during download, transmission, or storage. For example, if there is an issue with network connectivity at the time of download, the file may not download correctly. Issues with hard drive storage could also lead to file alteration.

Procedure

How to calculate the CheckSum of a file (Windows)

  1. Open Windows Powershell from the Windows menu.
Windows Powershell
  1. Type Get-FileHash.
Windows Powershell Administrator pane
  1. Drag and drop the file from Windows File Explorer into the Powershell window. The file need not reside on the same machine as the one running Powershell. If the file exists on a network drive, open that directory either via a UNC path or a mapped letter drive in Windows File Explorer, then drag and drop that file into the Powershell window as shown below. 
Drag and drop file from Windows File Explorer
  1. After the filename, type a space then -Algorithm MD5 to ensure the MD5 algorithm is being used. The final command should look like the command below, where <filepath> is the full path of the file. In this example, the path is C:\arcgis\ArcGISPro_23_167023.exe.  
Get-FileHash <filepath> -Algorithm MD5
  1. Press Enter. The output is the checksum value using the MD5 algorithm.
Windows Powershell Administrator pane showing the output checksum value
 
  1. The output checksum value can be then compared to the checksum values provided by Esri. For example, product downloads can be verified with the Downloads page of My Esri:
    1. Go to my.esri.com
    2. Click My Organizations.
    3. Click Downloads.
    4. Select View Downloads for the appropriate product and version.
    5. In the Download Components tab, expand Product Components, and locate the appropriate product.
    6. Click the blue link for Additional Information, the checksum (MD5) is listed here.
My Esri Downloads

How to calculate the CheckSum of a file (Linux)

  1. Change directory to the location of the file.
  2. Type md5sum then a space, followed by the full name of the file.
md5sum ArcGIS_Server_Linux_1061_164044.tar.gz
  1. Press Enter to execute the command.
85bb36e13c3b00fabcd97ff3f244bd26  ArcGIS_Server_Linux_1061_164044.tar.gz
  1. The output is the checksum value using the MD5 algorithm followed by the filename.
  2. The output checksum value can then be compared to the checksum values provided by Esri. For example, product downloads can be verified with the Downloads page of My Esri:
    1. Go to my.esri.com.
    2. Click My Organizations.
    3. Click Downloads.
    4. Select View Downloads for the appropriate product and version.
    5. In the Download Components tab, expand Product Components to locate the appropriate product.
    6. Click the blue link for Additional Information. The checksum (MD5) is listed here.
My Esri Downloads

Related Information

Last Published: 12/8/2020

Article ID: 000020408

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