Linux系统每日增量备份定时任务配置需求（支持tar/cpio/dump命令）

Hey there! Let's figure out how to set up a daily incremental backup that only grabs files modified in the previous day. I'll break down methods using tar, cpio, and dump—plus how to automate it with cron.

tar has a built-in --newer flag that makes filtering files by modification date straightforward. Here's how to use it:

Step 1: Test the Backup Command #

First, run this command manually to verify it works (replace /path/to/backup with the directory/files you want to back up):

tar -czf /backup/daily_incr_$(date +%Y%m%d).tar.gz \
  --newer=$(date -d "yesterday" +%Y-%m-%d) \
  /path/to/backup \
  --exclude=/proc --exclude=/sys --exclude=/dev

• -c: Create a new archive
• -z: Compress with gzip
• -f: Specify the output file name (we include the date for easy tracking)
• --newer=$(date -d "yesterday" +%Y-%m-%d): Only include files modified on or after yesterday's date
• --exclude: Skip system directories that don't need backing up (adjust these based on your setup)

Step 2: Automate with Cron #

Open your crontab editor (use sudo crontab -e if you need root access):

0 2 * * * /bin/bash -c 'tar -czf /backup/daily_incr_$(date +%Y%m%d).tar.gz --newer=$(date -d "yesterday" +%Y-%m-%d) /path/to/backup --exclude=/proc --exclude=/sys --exclude=/dev >> /var/log/daily_backup.log 2>&1'

This runs the backup every day at 2 AM. The >> /var/log/daily_backup.log 2>&1 part logs all output and errors to a file for troubleshooting.

cpio works with find to filter files by modification time. It's a bit more flexible for complex filtering:

Step 1: Test the Backup Command #

Run this to test (again, replace /path/to/backup):

find /path/to/backup -type f -mtime -1 \
  ! -path '/proc/*' ! -path '/sys/*' ! -path '/dev/*' \
  | cpio -ocv | gzip > /backup/daily_incr_$(date +%Y%m%d).cpio.gz

• find ... -mtime -1: Finds files modified in the last 24 hours (yesterday to now)
• ! -path: Excludes system directories
• cpio -ocv: Creates an archive (-o), uses ASCII format for compatibility (-c), and shows verbose output (-v)
• gzip: Compresses the archive to save space

Step 2: Automate with Cron #

Add this line to your crontab:

0 2 * * * /bin/bash -c "find /path/to/backup -type f -mtime -1 ! -path '/proc/*' ! -path '/sys/*' ! -path '/dev/*' | cpio -ocv | gzip > /backup/daily_incr_$(date +%Y%m%d).cpio.gz >> /var/log/daily_backup.log 2>&1"

Same as before—runs at 2 AM and logs activity.

dump is a filesystem-specific tool, so it works on entire partitions rather than individual directories. It's great for consistent backups of system partitions.

Step 1: First, Take a Full Backup #

Before doing incremental backups, you need a base full backup (replace /dev/sda1 with your target filesystem):

dump -0u -z -f /backup/full_$(date +%Y%m%d).dump.gz /dev/sda1

• -0: Full backup (level 0)
• -u: Updates /etc/dumpdates to track when the backup was run
• -z: Compresses the archive with gzip
• -f: Specifies the output file

Step 2: Daily Incremental Backups #

Now, set up daily incremental backups that only include files modified since the last backup:

dump -1u -z -f /backup/daily_incr_$(date +%Y%m%d).dump.gz /dev/sda1

• -1: Incremental backup (level 1), which backs up all files changed since the last level 0 or level 1 backup (since we run this daily, it'll only grab yesterday's changes)

Step 3: Automate with Cron #

Add these lines to your crontab to run a full backup on the first of every month, and incremental backups daily:

0 1 1 * * /bin/bash -c 'dump -0u -z -f /backup/full_$(date +%Y%m%d).dump.gz /dev/sda1 >> /var/log/daily_backup.log 2>&1'
0 2 * * * /bin/bash -c 'dump -1u -z -f /backup/daily_incr_$(date +%Y%m%d).dump.gz /dev/sda1 >> /var/log/daily_backup.log 2>&1'

The full backup runs at 1 AM on the first day of each month, and incremental backups run at 2 AM daily.

Important Notes for All Methods #

• Make sure the /backup directory exists and has write permissions for the user running the cron job (use sudo mkdir -p /backup if needed)
• Test restoring backups periodically to ensure they work—there's no point in backups you can't recover from!
• Adjust the exclude paths and backup times to fit your system's needs

内容的提问来源于stack exchange，提问作者Marcel Brou