1. Verifying on Linux (Ubuntu, Debian, Fedora)
Use the standard `sha256sum` utility built into GNU coreutils:
BASHSyntax Example
# Single file check:
sha256sum ubuntu-24.04-desktop-amd64.iso
# Automated batch verification against published SHA256SUMS file:
sha256sum -c SHA256SUMS 2>&1 | grep OK2. Verifying on macOS (Terminal)
Use the built-in `shasum` command with the `-a 256` flag:
BASHSyntax Example
shasum -a 256 /path/to/downloaded-installer.dmg3. Verifying on Windows (PowerShell)
Open PowerShell and execute `Get-FileHash`:
POWERSHELLSyntax Example
Get-FileHash -Algorithm SHA256 .\software-installer.exe4. What to Do If Checksums Do Not Match
If the computed checksum differs by even a single character from the vendor’s published hash:
1. Do NOT execute or open the file.
2. Delete the file immediately.
3. Re-download from an authentic official mirror over HTTPS.