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Git Reset

git reset can move a branch reference and, depending on its mode, change the index and working tree. Distinguish those effects before choosing it.

How it works

This exercise uses --soft on a private local commit. The branch returns to its parent while the new content stays staged. That lets you reconstruct a commit without discarding its files. The lesson does not use --hard; that mode can discard tracked working changes and needs a separate, deliberate recovery plan.

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 reset.ps1 in a separate empty learning folder and run it in a separate process: powershell -NoProfile -ExecutionPolicy Bypass -File .\reset.ps1. The execution-policy option applies to that process, not your machine policy.

The script creates bhylu-git-reset 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 reset.ps1 lab

Example

reset.ps1

# Bhylu Git lab: Reset
# 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-reset'
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
    Write-LabFile 'notes.md' 'Revised inspection draft'
    git add '--' 'notes.md'
    git commit -m 'Record draft too early'
    $draft = git rev-parse HEAD
    git branch saved-draft $draft
    git reset --soft HEAD~1
    Assert-Equal (git rev-list --count HEAD) @('1')
    Assert-Equal (git show :notes.md) @('Revised inspection draft')
    Assert-Equal (git show saved-draft:notes.md) @('Revised inspection draft')
    git status --short
    Write-Output 'Verified: reset'
} 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

Write-LabFile 'notes.md' 'Revised inspection draft'
git add '--' 'notes.md'
git commit -m 'Record draft too early'
$draft = git rev-parse HEAD
git branch saved-draft $draft
git reset --soft HEAD~1
Assert-Equal (git rev-list --count HEAD) @('1')
Assert-Equal (git show :notes.md) @('Revised inspection draft')
Assert-Equal (git show saved-draft:notes.md) @('Revised inspection draft')
git status --short

Expected result

main has one reachable commit, the revised note remains staged and saved-draft still names the original commit.

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

The saved branch makes the private tip easy to recover. A mixed reset also resets the index while preserving working files; a path-limited reset has different reference effects. Do not apply one simplified description to every reset form.

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