Git Version Control Tutorial

$ git config --list
core.repositoryformatversion=0 (1)
core.filemode=true (2)
core.bare=false (3)
core.logallrefupdates=true (4)

$ git config --global --add user.name "Urs Roesch" (1)
$ git config --global --add user.email "****@bun.ch" (2)
$ git config --list
user.email=****@bun.ch
user.name=Urs Roesch
core.repositoryformatversion=0
core.filemode=true
core.bare=false
core.logallrefupdates=true

$ cat ~/.gitconfig
[user]
        email = ****@bun.ch
        name = Urs Roesch
$ cat .git/config
[core]
        repositoryformatversion = 0
        filemode = true
        bare = false
        logallrefupdates = true

git config --global core.editor emacs (1)

git config --global core.pager '' (1)

git config --global color.ui false (1)

$ git config --list color.TabTab
color.advice
color.advice.hint
color.blame.highlightRecent
color.blame.repeatedLines
color.branch
...

git config --local credential.https://git.bun.ch/repo/foobar.git urs.roesch (1)

git config --global credential.helper 'cache --timeout=86400' (1)

$ mkdir git-repo
$ cd git-repo
$ git init (1)
Initialized empty Git repository in .../git-repo/.git/

$ echo "This is my first file in a git repo" > first-file.txt (1)
$ git status (2)
On branch main (3)

No commits yet

Untracked files:
  (use "git add <file>..." to include in what will be committed)

        first-file.txt

nothing added to commit but untracked files present (use "git add" to track) (4)

$ git add . (1)
$ git status
On branch main

No commits yet

Changes to be committed:
  (use "git rm --cached <file>..." to unstage) (2)

        new file:   first-file.txt (3)

$ git commit -m "My first git commit" (1)
[main (root-commit) 307c1a0] My first git commit (2)
 1 file changed, 1 insertion(+) (3)
 create mode 100644 first-file.txt (4)
$ git status
On branch main
nothing to commit, working tree clean (5)

$ git mv first-file.txt first_file.txt (1)
$ git status
On branch main
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
        renamed:    first-file.txt -> first_file.txt (2)

$ git rm first_file.txt (1)
rm 'first_file.txt'
$ git status
On branch main
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
        deleted:    first_file.txt (2)

$ git log
commit 307c1a0a537758f3d4b6ecea98e9af2e5d0b7b88 (HEAD -> main) (1)
Author: Urs Roesch <****@bun.ch> (2)
Date:   Sun Aug 26 12:09:57 2018 +0200 (3)

    My first git commit (4)

$ git log --stat
commit 307c1a0a537758f3d4b6ecea98e9af2e5d0b7b88 (HEAD -> main)
Author: Urs Roesch <urs++git@bun.ch>
Date:   Sun Aug 26 12:09:57 2018 +0200

    My first git commit

 first-file.txt | 1 + (1)
 1 file changed, 1 insertion(+) (2)

$ git log --oneline
307c1a0 (HEAD -> main) My first git commit (1)

$ git show
commit 307c1a0a537758f3d4b6ecea98e9af2e5d0b7b88 (HEAD -> main)
Author: Urs Roesch <urs++git@bun.ch>
Date:   Sun Aug 26 12:09:57 2018 +0200

    My first git commit

diff --git a/first-file.txt b/first-file.txt (1)
new file mode 100644
index 0000000..e7e0b37
--- /dev/null
+++ b/first-file.txt
@@ -0,0 +1 @@
+This is my first file in a git repo

$ git show --stat (1)
commit 307c1a0a537758f3d4b6ecea98e9af2e5d0b7b88 (HEAD -> main)
Author: Urs Roesch <urs++git@bun.ch>
Date:   Sun Aug 26 12:09:57 2018 +0200

    My first git commit

 first-file.txt | 1 +
 1 file changed, 1 insertion(+)

$ mkdir tmp
$ echo temporary > tmp/tmp.txt (1)
$ git status --short
?? tmp/ (2)
echo tmp > .gitignore (3)
git status --short
?? .gitignore (4)

$ git add .gitignore  (1)
$ git commit -m "Excluding files with .gitignore" (2)
[main 33d3825] Excluding files with .gitignore
 1 file changed, 1 insertion(+)
 create mode 100644 .gitignore
$ git log --oneline (3)
33d3825 (HEAD -> main) Excluding files with .gitignore
307c1a0 My first git commit

$ cat .gitignore
*.a (1)

!lib.a (2)

[0-9]*.html (3)

/TODO (4)

build/ (5)

doc/*.txt (6)

doc/**/*.pdf (7)

$ git init --shared --bare remote-repo.git (1) (2)
Initialized empty shared Git repository in .../remote-repo.git/

$ git clone remote-repo.git (1) (2)
Cloning into 'remote-repo'...
warning: You appear to have cloned an empty repository.
done.

$ git config --list
user.email=urs++git@bun.ch
user.name=Urs Roesch
core.repositoryformatversion=0
core.filemode=true
core.bare=false
core.logallrefupdates=true
remote.origin.url=.../remote-repo.git (1)
remote.origin.fetch=+refs/heads/*:refs/remotes/origin/* (2)
branch.main.remote=origin (3)
branch.main.merge=refs/heads/main (4)

$ echo 'First remote repository content!' > first_file.txt (1)
$ git add first_file.txt (2)
$ git commit -m 'Initial commit' (3)
[main (root-commit) 45d5290] Initial commit
 1 file changed, 1 insertion(+)
 create mode 100644 first_file.txt
$ git log --oneline
45d5290 (HEAD -> main) Initial commit

$ git push
Counting objects: 3, done. (1)
Writing objects: 100% (3/3), 250 bytes | 250.00 KiB/s, done. (2)
Total 3 (delta 0), reused 0 (delta 0)
To .../remote-repo.git (3)
 * [new branch]      main -> main (4)

$ cd ..
$ git clone remote-repo.git remote-repo2
Cloning into 'remote-repo2'...
done.
$ cd remote-repo2/
$ git log --oneline
45d5290 (HEAD -> main) Initial commit
$ echo "Second file" > second_file.txt
$ git add second_file.txt
$ git commit -m "Second commit"
[main 885f6c7] Second commit
 1 file changed, 1 insertion(+)
 create mode 100644 second_file.txt
$ git push
Counting objects: 3, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 290 bytes | 290.00 KiB/s, done.
Total 3 (delta 0), reused 0 (delta 0)
To .../remote-repo.git
   45d5290..885f6c7  main -> main
$ cd ../remote-repo

$ git fetch
remote: Counting objects: 3, done. (1)
remote: Compressing objects: 100% (2/2), done.
remote: Total 3 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (3/3), done.
From .../remote-repo
   45d5290..885f6c7  main     -> origin/main (2)

$ ls
first_file.txt (1)
$ git log --oneline
45d5290 (HEAD -> main) Initial commit (2)

$ git log origin/main (1)
commit 885f6c751abb430cb48c0903fcd82a2d35a77d25 (origin/main) (2)
Author: Urs Roesch <urs++git@bun.ch>
Date:   Thu Sep 6 06:57:50 2018 +0200

    Second commit

commit 45d52900b73a5bd461cbaef2652b9d1ed8220b3b (HEAD -> main) (3)
Author: Urs Roesch <urs++git@bun.ch>
Date:   Thu Sep 6 06:37:46 2018 +0200

    Initial commit

$ git merge origin/main (1)
Updating 45d5290..885f6c7
Fast-forward
 second_file.txt | 1 + (2)
 1 file changed, 1 insertion(+)
 create mode 100644 second_file.txt
$ git log
commit 885f6c751abb430cb48c0903fcd82a2d35a77d25 (HEAD -> main, origin/main) (3)
Author: Urs Roesch <urs++git@bun.ch>
Date:   Thu Sep 6 06:57:50 2018 +0200

    Second commit

commit 45d52900b73a5bd461cbaef2652b9d1ed8220b3b
Author: Urs Roesch <urs++git@bun.ch>
Date:   Thu Sep 6 06:37:46 2018 +0200

    Initial commit

$ git log origin/main
commit 45d52900b73a5bd461cbaef2652b9d1ed8220b3b (HEAD -> main, origin/main)
Author: Urs Roesch <urs++git@bun.ch>
Date:   Thu Sep 6 06:37:46 2018 +0200

    Initial commit
$ git pull
remote: Counting objects: 3, done. (1)
remote: Compressing objects: 100% (2/2), done.
remote: Total 3 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (3/3), done.
From .../remote-repo
   45d5290..885f6c7  main     -> origin/main
Updating 45d5290..885f6c7
Fast-forward (2)
 second_file.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 second_file.txt

$ echo 'second line in first file' >> first_file.txt (1)
$ cat first_file.txt (2)
First remote repository content!
second line in first file
$ git diff (3)
diff --git a/first_file.txt b/first_file.txt
index 697ffc4..f79ba9f 100644
--- a/first_file.txt
+++ b/first_file.txt
@@ -1 +1,2 @@
 First remote repository content!
+second line in first file

$ git add first_file.txt (1)
$ git diff (2)
$ git diff --cached (3)
diff --git a/first_file.txt b/first_file.txt
index 697ffc4..f79ba9f 100644
--- a/first_file.txt
+++ b/first_file.txt
@@ -1 +1,2 @@
 First remote repository content!
+second line in first file

$ git commit -m "Second line in first file" (1)
[main 3fb25c5] Second line in first file
 1 file changed, 1 insertion(+)
$
urs@automatix:~/var/work/git-tutorial/remote-repo$ git diff HEAD~1 (2)
diff --git a/first_file.txt b/first_file.txt
index 697ffc4..f79ba9f 100644
--- a/first_file.txt
+++ b/first_file.txt
@@ -1 +1,2 @@
 First remote repository content!
+second line in first file

$ git diff --stat HEAD~2 (1)
 first_file.txt  | 1 +
 second_file.txt | 1 +
 2 files changed, 2 insertions(+)

$ git diff HEAD~2 second_file.txt (1)
diff --git a/second_file.txt b/second_file.txt
new file mode 100644
index 0000000..20d5b67
--- /dev/null
+++ b/second_file.txt
@@ -0,0 +1 @@
+Second file

$ git blame first-file.txt
^8070030 (Urs Roesch        2018-10-06 13:06:01 +0000  1) First file (1)
2e97d380 (Linux Torvalds    2019-12-25 08:07:28 +0000  2) Second line (2)
e5149955 (Junio C Hamano    2020-01-04 11:08:45 +0000  3) Third line (3)
e5149955 (Junio C Hamano    2020-01-04 11:08:45 +0000  4) Fourth line
e5149955 (Junio C Hamano    2020-01-04 11:08:45 +0000  5) Fifth line
00000000 (Not Committed Yet 2020-10-03 09:10:49 +0000  6) (4)
00000000 (Not Committed Yet 2020-10-03 09:10:49 +0000  7)
00000000 (Not Committed Yet 2020-10-03 09:10:49 +0000  8)
00000000 (Not Committed Yet 2020-10-03 09:10:49 +0000  9)
00000000 (Not Committed Yet 2020-10-03 09:10:49 +0000 10) Apologies, I lost count

$ git blame 2e97d380.. -- first-file.txt
^2e97d38 (Linux Torvalds    2019-12-25 08:07:28 +0000  1) First file (1)
^2e97d38 (Linux Torvalds    2019-12-25 08:07:28 +0000  2) Second line
e5149955 (Junio C Hamano    2020-01-04 11:08:45 +0000  3) Third line (2)
e5149955 (Junio C Hamano    2020-01-04 11:08:45 +0000  4) Fourth line
e5149955 (Junio C Hamano    2020-01-04 11:08:45 +0000  5) Fifth line (3)

$ git blame 80700303..2e97d380 -- first-file.txt
^8070030 (Urs Roesch        2018-10-06 13:06:01 +0000  1) First file (1)
2e97d380 (Linux Torvalds    2019-12-25 08:07:28 +0000  2) Second line (2)

$ git blame ..2e97d380 -- first-file.txt
^8070030 (Urs Roesch        2018-10-06 13:06:01 +0000  1) First file (1)
2e97d380 (Linux Torvalds    2019-12-25 08:07:28 +0000  2) Second line (2)

$ git blame -L 2,4 first-file.txt
2e97d380 (Linux Torvalds    2019-12-25 08:07:28 +0000  2) Second line (1)
e5149955 (Junio C Hamano    2020-01-04 11:08:45 +0000  3) Third line
e5149955 (Junio C Hamano    2020-01-04 11:08:45 +0000  4) Fourth line (2)

$ cat first-file.txt
First file
Second line
Third line
Fourth line
Fifth line

$ git grep First
first-file.txt:First file (1)

$ cp first-file.txt first-file.copy (1)
$ git add first-file.copy (2)

$ git grep First
first-file.txt:First file
first-file.copy:First file (3)

$ git grep First -- '*.txt' (4)
first-file.txt:First file (5)

$ echo "Second file" > second-file.txt (1)
$ git grep --untracked Second (2)
second-file.txt:Second file (3)

$ git tag (1)
v1.0.0 (2)
v1.1.0

$ git tag v1.3.0 (1)

$ git tag v1.2.0 64b67952 (1)

$ git tag -a milestone_1 -m "This is the first milestone" (1)
$ git show milestone_1 (2)
tag milestone_1 (3)
Tagger: Urs Roesch <Urs Roesch>
Date:   Sun Nov 8 17:17:17 2020 +0100

This is our first milestone (4)

commit 45a6088dd900e5363dddbb656360661adb94c1a1 (HEAD -> production, tag: milestone_1) (5)
Author: Urs Roesch <Urs Roesch>
Date:   Sun Nov 8 10:47:36 2020 +0100

    first-file: New milestone reached

$ git push --tags (1)
Enumerating objects: 9, done. (2)
Counting objects: 100% (9/9), done.
Delta compression using up to 8 threads
Compressing objects: 100% (5/5), done.
Writing objects: 100% (7/7), 748 bytes | 748.00 KiB/s, done.
Total 7 (delta 0), reused 0 (delta 0), pack-reused 0
To https://github.com/octocatterpillar/git-tutorial.git
 * [new tag]         milestone_1 -> milestone_1 (3)

$ git tag -d v1.1.0 (1)

$ git tag -d v1.1.0 (1)

$ git branch
* main (1)

$ git branch testing (1)
$ git branch
* main (2)
  testing
$ git checkout testing (3)
Switch to branch 'testing'
$ git branch
  main
* testing (4)

$ echo 'Branched file' > branched-file.txt (1)
$ git add branched-file.txt
$ git commit -a -m  "First file under branch testing" (2)
[testing 4b9b86d] First file under branch testing
 1 file changed, 1 insertion(+)
 create mode 100644 branched-file.txt

$ git checkout main
Switched to branch 'main'
$ git branch
* main (1)
  testing

$ git checkout -b bugfix (1)
Switched to a new branch 'bugfix'
$ git branch
* bugfix (2)
  main
  testing

$ git diff
diff --git a/first-file.txt b/first-file.txt
index 4c5fd91..aa24abd 100644
--- a/first-file.txt
+++ b/first-file.txt
@@ -1 +1 @@
-First file
+First file with bugfix (1)
$ git commit -a -m "Bugfix for first file"
[bugfix a27a927] Bugfix for first file
 1 file changed, 1 insertion(+), 1 deletion(-)

$ git checkout main (1)
Switched to branch 'main'
$ git branch
* main (2)
  testing
$ git merge bugfix (3)
Updating e303af7..a27a927
Fast-forward
 first-file.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

$ git branch
  bugfix
* main (1)
  testing
$ git branch -d  bugfix (2)
Deleted branch bugfix (was a27a927).
$ git log  --oneline -n 1
a27a927 (HEAD -> main) Bugfix for first file (3)

$ git branch (1)
* main
  testing
$ git checkout testing (2)
Switched to branch 'testing'
$ git rebase main (3)
Successfully rebased and updated refs/heads/testing. (4)

$ git branch (1)
* main
  testing
$ git checkout testing (2)
Switched to branch 'testing'
$ git branch -m production (3)
$ git branch
  main
* production (4)

$ git checkout main (1)
Switched to branch 'main'
$ vi first-file.txt (2)
$ cat first-file.txt
First file with bugfix from branch "main" (3)
$ git commit -m "first-file: Add from 'main'" first-file.txt  (4)
[main 64b6795] first-file: Add from 'main'
 1 file changed, 1 insertion(+), 1 deletion(-)

$ git checkout production (1)
Switched to branch 'production'
$ vi first-file.txt (2)
$ cat first-file.txt (3)
First file with bugfix from branch "production"
$ git commit -m "first-file: Add from 'production'" first-file.txt (4)
[production bdfdc4a] first-file: Add from 'production'
 1 file changed, 1 insertion(+), 1 deletion(-)

$ git rebase main
Auto-merging first-file.txt (1)
CONFLICT (content): Merge conflict in first-file.txt (2)
error: could not apply bdfdc4a... first-file: Add from 'production'
Resolve all conflicts manually, mark them as resolved with (3)
"git add/rm <conflicted_files>", then run "git rebase --continue".
You can instead skip this commit: run "git rebase --skip".
To abort and get back to the state before "git rebase", run "git rebase --abort".
Could not apply bdfdc4a... first-file: Add from 'production'

$ git branch (1)
* (no branch, rebasing production) (2)
  main
  production

$ cat first-file.txt (1)
<<<<<<< HEAD (2)
First file with bug fix from branch "main" (3)
======= (4)
First file with bug fix from branch "production" (5)
>>>>>>> bdfdc4a... first-file: Add from 'production' (6)

$ vi first-file.txt (1)
$ cat first-file.txt
First file with bugfix from branch "main" and from "production" (2)
$ git add first-file.txt (3)
$ git rebase --continue (4)
(5)
[detached HEAD 7c857af] first-file: Add from 'main' and 'production'
 1 file changed, 1 insertion(+), 1 deletion(-)
Successfully rebased and updated refs/heads/production.
$ git branch
  main
* production (6)

$ git checkout --theirs -- first-file.txt (1)
$ cat first-file.txt
First file with bugfix from branch "production" (2)
$ git add first-file.txt (3)
$ git rebase --continue (4)
(5)
[detached HEAD 45a6088] first-file: Add from 'production'
 1 file changed, 1 insertion(+), 1 deletion(-)
Successfully rebased and updated refs/heads/production.
$ git branch
  main
* production (6)

$ git checkout --ours -- first-file.txt (1)
$ cat first-file.txt
First file with bugfix from branch "main" (2)
$ git add first-file.txt (3)
$ git rebase --continue (4)
Successfully rebased and updated refs/heads/production.
$ git branch
  main
* production (5)

$ git config --global alias.co checkout (1)
$ git config --global alias.ci commit
$ git config --global alias.br branch
$ git config --global alias.st status

$ git st --short (2)
A  second-file.txt

$ git config --global alias.lol  'log --oneline --no-decorate' (1)
$ git config --global alias.top 'log -n 3 HEAD' (2)

$ git lol
49b7a9c The rest (3)
e514995 Third line
2e97d38 Second line
8070030 First commit

$ git config --global alias.top 'log -n 1 HEAD' (1)

$ git top
commit 49b7a9cf2a8f1ae6ba94141268716ba0b07949d6 (HEAD -> main)
Author: Urs Roesch <github@bun.ch>
Date:   Tue Nov 3 05:23:49 2020 +0000

    The rest

$ git config --global --unset alias.top (1)
$ git config --global --get-regex 'alias.*' (2)
alias.st=status
alias.lol=log --oneline --no-decorate
alias.co=checkout
alias.ci=commit
alias.br=branch

$ git config --global alias.sync-upstream \
  '!sh -x -c "git fetch upstream && git rebase upstream/main main"' (1)

$ git sync-upstream
+ git fetch upstream (2)
From https://github.com/sample/repository (3)
   41cc734..1bd94bb  main       -> upstream/main
 * [new tag]         v1.60      -> v1.60
+ git rebase upstream/main main (4)
Current branch main is up to date. (5)

$ git config --global alias.vi '!sh -x -c "vi \"$@\" && git add \"$@\""' (1)

$ git vi second-file.txt
+ vi second-file.txt (2)
+ git add second-file.txt

#!/usr/bin/env bash

# -----------------------------------------------------------------------------
# Small script to push upstream without a fuss
# -----------------------------------------------------------------------------

# -----------------------------------------------------------------------------
# Setup
# -----------------------------------------------------------------------------
set -o errexit
set -o nounset
set -o pipefail

# check bash version compatiblity requires 4.2 or better
shopt -u compat41 2>/dev/null || {
  echo -n "\nBash Version 4.2 or higher is required!\n";
  exit 127;
}

# -----------------------------------------------------------------------------
# Globals
# -----------------------------------------------------------------------------
declare -r SCRIPT=${0##*/}
declare -r VERSION=0.6.1
declare -r AUTHOR="Urs Roesch <github@bun.ch>"
declare -r LICENSE="GPLv2"
declare -g FORCE=""
declare -g BASE=""
declare -g REMOVE=""
declare -a DEFAULT_BASES=( master main )

# -----------------------------------------------------------------------------
# Functions
# -----------------------------------------------------------------------------
function usage() {
  local exit_code=${1:-1}
  cat <<USAGE

  Usage:
    ${SCRIPT/-/ } [options]

  Opttions:
    -h | --help    This message
    -f | --force   Force a push to upstream
    -r | --remove  Remove the repository from upstream
    -b | --base    Set the default base branch
                   Default: 'main' or 'master'
    -V | --version Display version and exit

  Description:
    Origin push to upstream without a fuss. Exludes pushes to master/main.

USAGE

  exit ${exit_code}
}

# -----------------------------------------------------------------------------

function parse_options() {
  while [[ ${#} -gt 0 ]]; do
    case ${1} in
    -h|--help)    usage 0;;
    -b|--base)    shift; BASE=${1};;
    -f|--force)   FORCE="true";;
    -r|--remove)  REMOVE="true";;
    -V|--version) version;;
    -*)           usage 1;;
    esac
    shift
  done
}

# -----------------------------------------------------------------------------

function version() {
  printf "%s v%s\nCopyright (c) %s\nLicense - %s\n" \
    "${SCRIPT/-/ }" "${VERSION}" "${AUTHOR}" "${LICENSE}"
  exit 0
}

# -----------------------------------------------------------------------------

function current_branch() {
  git rev-parse --abbrev-ref HEAD
}

# -----------------------------------------------------------------------------

function join_array() {
  local -- char=${1}; shift;
  local -a array=( "${@}" )
  printf -v string "%s${char}" "${array[@]}"
  echo "${string%${char}}"
}

# -----------------------------------------------------------------------------

function which_base() {
  [[ -n ${BASE} ]] && return 0
  # prefer master over main
  local pattern=$(join_array '|' "${DEFAULT_BASES[@]}")
  local -a branches=( $(git branch | grep -oE "\<(${pattern})\>" | sort -r ) )
  BASE=${branches[0]:-}
}

# -----------------------------------------------------------------------------

function push_origin() {
  local branch=$(current_branch)
  if [[ ${branch} == ${BASE} ]]; then
    echo "Not pushing ${BASE}!"
    exit 1
  fi
  git push ${FORCE:+-f} origin ${REMOVE:+:}${branch}
}

# -----------------------------------------------------------------------------

function push_tags() {
  git push --tags
}

# -----------------------------------------------------------------------------
# Main
# -----------------------------------------------------------------------------
parse_options "${@}"
which_base
push_origin
push_tags

$ git opush
Not pushing main!