(macOS) Rsync a file, check that backup was successful, and send a message to the printlog function

backup.sh

# Rsync a file, check that backup was successful, and send a message to the printlog function
# Printlog function is available at https://gist.github.com/bwmorales/86a1a8c4ec51c9e2ffba1499a2c211e0
# Example Usage:
# backup $HOME/Documents/myfile.txt

export TODAY=$(date +"%Y-%m-%d")

backup() {
    if [[ -e "${1}" ]]; then
        rsync -aE "${1}" "${1}.${TODAY}.bak"
        if [[ -e "${1}.${TODAY}.bak" ]]; then
            if [[ "$(shasum "${1}" | awk '{ print $1 }')" == "$(shasum "${1}.${TODAY}.bak" | awk '{ print $1 }')" ]]; then
                printlog -g "Backup of '${1}' succeeded."
                return 0
            else
                printlog -r "Backup of '${1}' failed."
                return 1
            fi
        else
            printlog -r "Backup of '${1}' failed."
            return 1
        fi
    else
        printlog -y "'${1}' does not exist. Skipping."
        return 0
    fi
}