Bash function to check for git updates in the current repo with nice output

git_check.sh

# Check to see if there are new commits on the current branch
function check() {

  # Check if in a git repo
  git status &>/dev/null
  test $? -ne 0 && printf "Not a git repo\n" && return 1

  # Fetch latest commits from git remote
  printf "\n${details}Checking for latest git changes...$n"
  git fetch &>/dev/null
  test $? -ne 0 && printf "\rFailed to check for updates from the git repo.\n\n" && return 1

  # Define variables
  if [[ $(tput colors) -eq 256 ]]; then
    # 256 color support
    local c_header="\e[4m\e[38;5;15m"
    local c_message="\e[1;80m"
    local c_hash="\e[38;5;178m"
    local c_committed="\e[38;5;110m"
    local c_author="\e[38;5;85m"
    local c_current="\e[38;5;15m"
    local c_newer="\e[38;5;185m"
    local c_older="\e[38;5;245m"
  else
    # 16 colors only
    local c_header="\e[1;32m"
    local c_message="\e[1;36m"
    local c_hash="\e[0;33m"
    local c_committed="\e[1;34m"
    local c_author="\e[1;36m"
    local c_current="\e[1;33m"
    local c_newer="\e[1;15m"
    local c_older="\e[37m"
  fi
  local n="\e[m" # Reset to normal
  local s=$'\x01' # Obscure ASCII character as a separator
  local counter=-1
  local show_previous=3
  local git_log_format="%h$s%cr$s%cd$s%s$s%an"
  local git_branch=$(git branch | grep '*' | cut -d' ' -f2)
  local not_yet_pulled="$(git log HEAD..origin/$git_branch --date=default --pretty=format:"$git_log_format" --decorate=full)"
  local local_commits="$(git log --date=default --pretty=format:"$git_log_format")"
  local count_available=$(echo -n "$not_yet_pulled" | grep -c '^')
  local output=$(printf "Timeline \b${s}Hash${s}Committed${s}Author${s}Commit Message$n")
  test $count_available -eq 1 && local is_or_are="is" || local is_or_are="are"

  # Display status line
  printf "\rThere $is_or_are $c_message$count_available$n new updates available on the $c_message$git_branch$n branch which can be pulled.\n\n$c_header"

  # Function to display a single line with the proper formatting
  print_git_log() {
    test -z "$1" && return
    if [[ $counter -eq 0 ]]; then
      local marker="${c_current}Current \b$n" # \b is a hack to get columns to line up due to multi-byte characters for Newer and Older arrows
    elif [[ $counter -lt 0 ]]; then
      local marker="${c_newer}Newer ▲$n"
    else
      local marker="${c_older}Older ▼$n"
    fi
    IFS="$s" read -r -a column <<< "$1"
    local hash="${column[0]}"
    local committed="${column[1]}"
    local commit_msg="${column[3]}"
    local author="${column[4]}"
    output="$( \
      printf "$output\n" && \
      printf "%s$s$c_hash%s$n$s$c_committed%s$n$s$c_author%s$n$s%s\n\n" "$marker" "$hash" "$committed" "$author" "$commit_msg" \
    )"
  }

  # Display Newer commits
  while read line; do
    print_git_log "$line"
  done <<< "$not_yet_pulled"

  # Display Current and Older commits
  counter=0
  while read line; do
    test $counter -eq $show_previous && break
    print_git_log "$line"
    let counter++
  done <<< "$local_commits"

  # Display the output in columns
  printf "$output\n" | column -s "$s" -t
  echo
}

check