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Git Tags

A tag names a useful version. An annotated tag also stores tag metadata and a message; signing adds a separate verification step.

How it works

The desk names its initial inspection checklist v0.1.0 with an annotated tag. We confirm that it is a tag object and that peeling it resolves to the current commit. A tag name is not a release package or a deployed website. Hosting providers may create release pages around tags, but those pages are separate products.

Run the disposable lab

Use Windows PowerShell 5.1 or later and Git 2.28 or later. The reviewed CLI is Git for Windows 2.53.0.windows.2. These are PowerShell examples, not Git Bash commands. Save the download as tags.ps1 in a separate empty learning folder and run it in a separate process: powershell -NoProfile -ExecutionPolicy Bypass -File .\tags.ps1. The execution-policy option applies to that process, not your machine policy.

The script creates bhylu-git-tags and refuses an existing folder. It supplies two fictional seed files and repository-local settings, then runs the lesson commands. The literal separator is quoted as '--' so PowerShell passes it through the guard. A guard function named git calls the real CLI and stops on unexpected failures; Expect-GitFailure checks deliberately refused operations. Child-process configuration isolates your personal Git settings. File transports are allowed only for owned local remotes; internet transports are disabled in this lab. No hosting account, Apache or MySQL service is required. There is no Git playground. Leave the generated folder for inspection; choose another empty parent to run again.

Download the complete tags.ps1 lab

Example

tags.ps1

# Bhylu Git lab: Tags
# Run in a separate PowerShell process, in an empty learning folder.
# Existing lab folders are refused; nothing is pushed to an internet host.
$ErrorActionPreference = 'Stop'
$script:GitExe = (Get-Command git -CommandType Application | Select-Object -First 1).Source
$script:LabRoot = Join-Path (Get-Location) 'bhylu-git-tags'
if (Test-Path -LiteralPath $script:LabRoot) { throw 'Lab folder already exists. Choose another empty parent folder.' }
New-Item -ItemType Directory -Path $script:LabRoot | Out-Null
$env:GIT_CONFIG_NOSYSTEM = '1'
$env:GIT_CONFIG_GLOBAL = Join-Path $script:LabRoot 'empty-global-config'
[IO.File]::WriteAllText($env:GIT_CONFIG_GLOBAL, '')
$env:GIT_TERMINAL_PROMPT = '0'
$env:GIT_EDITOR = 'true'
$env:GIT_SEQUENCE_EDITOR = 'true'
$env:GIT_AUTHOR_DATE = '2026-01-10T10:00:00+00:00'
$env:GIT_COMMITTER_DATE = $env:GIT_AUTHOR_DATE
function git {
    & $script:GitExe -c protocol.allow=never -c protocol.file.allow=always @args
    if ($LASTEXITCODE -ne 0) { throw "Git exited with code $LASTEXITCODE" }
}
function Expect-GitFailure {
    & $script:GitExe -c protocol.allow=never -c protocol.file.allow=always @args
    if ($LASTEXITCODE -eq 0) { throw 'Expected Git to refuse this operation' }
}
function Assert-Equal($Actual, $Expected) {
    if ((($Actual | Out-String).Trim()) -cne (($Expected | Out-String).Trim())) { throw "Expected [$Expected], got [$Actual]" }
}
function Write-LabFile([string]$Name, [string]$Text) {
    $target = [IO.Path]::GetFullPath((Join-Path (Get-Location) $Name))
    if (!$target.StartsWith($script:LabRoot + [IO.Path]::DirectorySeparatorChar, [StringComparison]::OrdinalIgnoreCase)) { throw 'Path outside lab' }
    [IO.Directory]::CreateDirectory([IO.Path]::GetDirectoryName($target)) | Out-Null
    [IO.File]::WriteAllText($target, ($Text.Replace('\n', "`n") + "`n"), (New-Object Text.UTF8Encoding($false)))
}
function New-LabRepo([string]$Name) {
    New-Item -ItemType Directory -Path $Name | Out-Null
    Push-Location $Name
    try {
        git init --initial-branch=main
        git config --local user.name 'Repair Lab'
        git config --local user.email 'repair@example.invalid'
        git config --local core.autocrlf false
        git config --local commit.gpgSign false
        git config --local tag.gpgSign false
        git config --local core.hooksPath (Join-Path $script:LabRoot 'empty-hooks')
        Write-LabFile 'notes.md' 'Inspect hinge'
        Write-LabFile 'tasks.txt' 'desk=open'
        git add '--' notes.md tasks.txt
        git commit -m 'Record initial repair plan'
    } finally { Pop-Location }
}
Push-Location $script:LabRoot
try {
    New-LabRepo 'desk'
    Set-Location desk
    git tag -a v0.1.0 -m 'First inspection checklist'
    Assert-Equal (git cat-file -t v0.1.0) @('tag')
    Assert-Equal (git rev-parse 'v0.1.0^{}') (git rev-parse HEAD)
    git show --no-patch v0.1.0
    Write-Output 'Verified: tags'
} finally { Pop-Location }
Focus on the lesson commands

This excerpt omits the seed repository and guard helpers. Use the complete download to run it.

Lesson excerpt

git tag -a v0.1.0 -m 'First inspection checklist'
Assert-Equal (git cat-file -t v0.1.0) @('tag')
Assert-Equal (git rev-parse 'v0.1.0^{}') (git rev-parse HEAD)
git show --no-patch v0.1.0

Expected result

The annotated tag points to the current commit and carries First inspection checklist as its message.

The complete script ends with Verified: tags only after its checks pass. Object IDs, temporary paths and progress output can differ.

Tags normally stay fixed as named versions. Moving a published tag can surprise consumers who already fetched the earlier value. Push selected tags deliberately rather than assuming every branch push includes all tags.

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