delete_branches_by_date.sh

#!/bin/bash

### Copy of https://gist.github.com/redthor/3776c1f726cafff41c9eda6f271466c3
### Adding in comments explaining each line/command in order to help learning
### Set DRY_RUN=1 to only echo the commands instead of executing them

#DRY_RUN=1



# Date parameter uses git log --since syntax
# i.e. "2 months ago" or just a simple date
date=$1


branches=           # store results of our filtered branch list to prevent 
                    # multiple calls to remote to get each branch again

for branch in $(git branch -a |     # call git for list of branches
    sed 's/^\s*//' |                # pipe list of branches to remove any whitespace
    sed 's/^remotes\///' |          # pipe list to remove remote/ from each branch
    grep -v 'main$' |               # pipe to grep to exclude main
    grep -v 'develop$'); do         # pipe to grep to exclude develop

    # Set of conditionals executed for each branch 
    if [[ "$(git log $branch --since $date | wc -l)" -eq 0 ]]; then # does branch log since date have wc > 0
        if [[ "$branch" =~ "origin/" ]]; then       # does branch start with origin/
            if [[ -z $branches ]]; then                             # if $branches is empty
                branches=$(echo "$branch" | sed 's/^origin\///')    # remove 'origin/' from $branch and add to branches
            else
                branches="$branches "$(echo "$branch" | sed 's/^origin\///') # add to branches
            fi
        fi
    fi
done


if [[ ! -z $branches ]]; then       # if $branches is not empty
    if [[ "$DRY_RUN" -eq 1 ]]; then # if DRY_RUN=1 then we just echo commands
        echo git branch -D $branches
        echo git push --delete origin $branches
    else                            # else we execute the commands to remove
        git branch -D $branches
        git push --delete origin $branches

        # clean up locally
        git remote prune origin
    fi
fi