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Git Push and Upstream

git push asks a remote repository to update references. Setting an upstream records a default relationship for later branch operations.

How it works

After establishing a local origin, the desk creates a delivery branch and pushes it with -u. The remote now has that branch while main stays unchanged. The test checks both the actual remote file and the configured upstream. This demonstrates branch exchange without contacting GitHub.

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

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

Example

push.ps1

# Bhylu Git lab: Push and Upstream
# 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-push'
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 init --bare --initial-branch=main ../shared.git
    git remote add origin ../shared.git
    git push -u origin main
    git switch -c delivery-note
    Write-LabFile 'delivery.txt' 'Return before closing'
    git add '--' 'delivery.txt'
    git commit -m 'Add delivery reminder'
    git push -u origin delivery-note
    Assert-Equal (git rev-parse --abbrev-ref --symbolic-full-name '@{upstream}') @('origin/delivery-note')
    Assert-Equal (git --git-dir=../shared.git show delivery-note:delivery.txt) @('Return before closing')
    Write-Output 'Verified: push'
} 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 init --bare --initial-branch=main ../shared.git
git remote add origin ../shared.git
git push -u origin main
git switch -c delivery-note
Write-LabFile 'delivery.txt' 'Return before closing'
git add '--' 'delivery.txt'
git commit -m 'Add delivery reminder'
git push -u origin delivery-note
Assert-Equal (git rev-parse --abbrev-ref --symbolic-full-name '@{upstream}') @('origin/delivery-note')
Assert-Equal (git --git-dir=../shared.git show delivery-note:delivery.txt) @('Return before closing')

Expected result

The remote delivery-note branch contains the reminder and tracks origin/delivery-note locally.

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

A push can be rejected because of history, permissions or server policy. The upstream is a local convenience, not a grant of remote write access. Tags are separate references and should be pushed intentionally.

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