Bash script for keeping X number of zip files, deleting the oldest one when limit is exceeded

backuprotate.sh

#!/bin/bash

# Directory containing the zip files
backup_dir="/path/to/backups"
log_file="/var/log/purge-backups.log"

# Maximum number of zip files to keep
max_files=30

cd "$backup_dir" || exit

# Create log file
if [ ! -e "$log_file" ]; then
    if ! touch "$log_file" > /dev/null 2>&1; then
        echo "[FATAL] Failed to create log file" | ts
        exit 1
    fi
fi

# Trim the file to only contain 100 + last session lines of logs
log_content=$(tail -n 100 $log_file)
echo "$log_content" > $log_file
unset $log_content

echo "[SESSION]" | ts | tee -a $log_file

# Count the number of zip files
num_files=$(ls -1 *.zip 2>/dev/null | wc -l)

# If there are more than max_files, delete the oldest ones
if [ "$num_files" -ge "$max_files" ]; then
    expired=$(ls -1t *.zip | tail -n +"$((max_files + 1))")

    if [ -z "$expired" ];
        then echo "[INFO] No files to remove" | ts | tee -a $log_file
        exit 0
    fi

    while IFS= read -r file; do
        echo "[INFO] Removing file: $file" | ts | tee -a $log_file
        if ! rm -f "$file"; then
            echo "[WARN] Failed to remove file: $file" | ts | tee -a $log_file
        fi
    done <<< "$expired"


fi