Update all git repos in a directory

update.sh

#!/bin/bash

# Updates all git repositories in a directory, doing some housekeeping along the
# way

    nocol="\033[m"
    green="\033[0;32m"
   yellow="\033[1;33m"
lightgrey="\033[0;37m"
 darkgrey="\033[1;30m"

update() {
    echo -ne $lightgrey
    echo -n "$(git rev-parse --abbrev-ref HEAD)"

    local tracking
    tracking=$(git for-each-ref --format='%(upstream:short)' "$(git symbolic-ref -q HEAD)")

    if [ -n "$tracking" ]
    then
        echo -n " ➡ $tracking"
    fi
    echo -ne $nocol

    if git show-ref -q "$tracking"
    then
        local ahead_behind
        ahead_behind=$(git rev-list --left-right --count "$tracking"...HEAD)
        local behind
        behind=$(echo "$ahead_behind" | cut -d$'\t' -f1)
        local ahead
        ahead=$(echo "$ahead_behind" | cut -d$'\t' -f2)

        if [ "$behind" -ne "0" ]
        then
            echo -n ", $behind behind"
        fi

        if [ "$ahead" -ne "0" ]
        then
            echo -n ", $ahead ahead"
        fi

        if [ "$behind" -ne "0" ]
        then
            if git merge -q --ff-only 2> /dev/null
            then
                echo -ne ", ${green}updated${nocol}"
            else
                echo -ne ", ${yellow}no update${nocol}"
            fi
        fi
    elif [ -n "$tracking" ]
    then
        echo -ne ", ${yellow}tracked ref missing${nocol}"
    fi

    echo
}

SOURCE_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)

for dir in "$SOURCE_DIR/"*/
do
    cd "$dir" || exit 1
    if test -d .git
    then
        current=$(git rev-parse --abbrev-ref HEAD)
        echo -ne $darkgrey
        basename "$PWD"
        echo -ne $nocol
        git fetch -pq

        echo -n "  "
        update

        main_branch=$(git symbolic-ref refs/remotes/origin/HEAD | cut -d'/' -f4-)
        if ! git rev-parse --quiet --verify "$main_branch" > /dev/null
        then
            # update the default branch if it's changed
            echo -n "  "
            git remote set-head origin --auto
            new_main_branch=$(git symbolic-ref refs/remotes/origin/HEAD | cut -d'/' -f4-)
            if [ "$current" == "$main_branch" ]
            then
                git checkout "$new_main_branch"
                if git branch -d "$main_branch"
                then
                    echo -e "  ${yellow}couldn't delete old main branch: ${main_branch}${nocol}"
                fi
            fi
            main_branch="$new_main_branch"
        fi

        if [ "$current" != "$main_branch" ]
        then
            if git checkout -q "$main_branch"
            then
                echo -n "  "
                update
                git checkout -q -
            else
                echo -e "  ${yellow}couldn't update ${main_branch}${nocol}"
            fi
        fi
    fi
    cd ..
done