Show all branches and whether they are up to date on the remote

gstrep.sh

#!/bin/bash

git fetch --quiet

message="Does not exist on remote!"
all_remote_branches=$(git branch -r)

echo -e "\n\e[1m remote\tlocal\tbranch name\e[0m"

git branch | while read line ; do
  output_line=""
        branch_name=${line//"* "}
        if [[ $all_remote_branches =~ .*origin\/$branch_name[[:space:]]+.* ]]; then
                branch_status=$(git rev-list --left-right --count origin/${branch_name}...${branch_name})
    output_line=" $branch_status\t"
                if [[ $branch_status =~ .*0[[:space:]]+0.* ]]; then
                        echo -e "$output_line\e[32m${branch_name}\e[0m"
                elif [[ $branch_status =~ .*[0-9][[:space:]]+0.* ]]; then
                        echo -e "$output_line\e[33m${branch_name}\e[0m"
    else
            echo -e "$output_line\e[31m${branch_name}\e[0m"
                fi
        else
                 echo -e " -\t-\t\e[31m${branch_name}\e[0m -> $message"
        fi
done

#!/bin/bash

Thanks @floriantschopp