Create crontab lines with scheduled random times

random_cron

#!/usr/bin/env bash
# ****************************************************************************
# Create radom cron job starting times
# for hourly, daily, weekly, monthly or yearly jobs
#
# https://gist.github.com/alainwolf/931316e4f5af0c45b352a1823ec3321c
# Copyright (C) 2024 Alain Wolf
# ****************************************************************************

# What kind of shedule do you want to create?
# hourly, daily, weekly or monthly
_SCHEDULE="$1"

# If three arguments are given, use the second as user and the third as the
# schduled command
if [ -n "$3" ]; then
    _USER="$2"
    _CMD="$3"
    printf "# min\thour\tmday\tmonth\twday\tuser\tcommand\n"

# If two arguments are given, use the second as command to schedule
elif [ -n "$2" ]; then
    _CMD="$2"
    printf "# min\thour\tmday\tmonth\twday\tcommand\n"
else
    printf "# min\thour\tmday\tmonth\twday\n"
fi

# Generate random values within the correct ranges
rand_min=$((RANDOM % 60))
rand_hour=$((RANDOM % 24))
rand_mday=$((1 + RANDOM % 28))
rand_month=$((1 + RANDOM % 12))
rand_wday=$((RANDOM % 7))

# Determine the cron schedule based on the provided schedule type
case "${_SCHEDULE}" in
hourly)
    printf "  %s\t%s\t%s\t%s\t%s" "$rand_min" "*" "*" "*" "*"
    ;;
daily)
    printf "  %s\t%s\t%s\t%s\t%s" "$rand_min" "$rand_hour" "*" "*" "*"
    ;;
weekly)
    printf "  %s\t%s\t%s\t%s\t%s" "$rand_min" "$rand_hour" "*" "*" "$rand_wday"
    ;;
monthly)
    printf "  %s\t%s\t%s\t%s\t%s" "$rand_min" "$rand_hour" "$rand_mday" "*" "*"
    ;;
yearly)
    printf "  %s\t%s\t%s\t%s\t%s" "$rand_min" "$rand_hour" "$rand_mday" "$rand_month" "*"
    ;;
*)
    echo "Usage: $0 hourly|daily|weekly|monthly|yearly [user] [command]"
    exit 1
    ;;
esac

# Append user and command if provided
if [ -n "$_USER" ]; then
    printf "\t%s" "$_USER"
fi

if [ -n "$_CMD" ]; then
    printf "\t%s" "$_CMD"
fi
# Print a newline at the end
echo