如何在使用crontab发送邮件时自定义带日期的邮件主题？

Got it, let's adjust your cron job so it sends emails with that custom subject you want. The default cron email subject is auto-generated, so we need to override how the email is sent instead of relying on cron's default behavior. Here are two straightforward methods:

Method 1: Modify the Cron Entry Directly #

Update your crontab line to pipe the script's output to the mail command, which lets you specify a custom subject (including the dynamic date).

Your modified crontab will look like this:

# 1am every day (EST)
00 05 * * * /bin/bash /home/ubuntu/mongo_backup.sh | mail -s "MyProjectName Backup - $(date +\%Y-\%m-\%d)" example@gmail.com

Key Notes: #

• The \% is critical! In crontab, the % character is a special symbol (it denotes a newline), so we have to escape it with a backslash for the date command to work correctly.
• The date +\%Y-\%m-\%d generates a date in YYYY-MM-DD format (e.g., 2024-05-20). You can tweak the format string if you want a different style (like \%d-\%m-\%Y for DD-MM-YYYY).
• This replaces cron's default email sending, so you can remove the MAILTO= line if you use this method—we're explicitly specifying the recipient in the mail command.

Method 2: Handle Email Inside Your Backup Script #

If you prefer to keep your crontab clean, you can add the email logic directly to your mongo_backup.sh script. This gives you more control over what's included in the email body too.

1. First, update your crontab to suppress cron's default email (we'll let the script handle sending):

MAILTO=example@gmail.com
# 1am every day (EST)
00 05 * * * /bin/bash /home/ubuntu/mongo_backup.sh >/dev/null 2>&1

2. Then, add this to the end of your mongo_backup.sh script (adjust the backup output capture as needed for your workflow):

# Capture the output of your backup process (replace with your actual backup command logs)
BACKUP_LOG=$(tail -n 20 /var/log/mongo_backup.log)

# Set the custom subject with dynamic date
SUBJECT="MyProjectName Backup - $(date +%Y-%m-%d)"

# Send the email with the log content
echo "$BACKUP_LOG" | mail -s "$SUBJECT" "$MAILTO"

Prerequisite: #

Make sure the mail utility is installed on your Ubuntu server. If not, install it with:

sudo apt update && sudo apt install mailutils

Either method will give you the custom email subject you're looking for—pick whichever fits your workflow better!

内容的提问来源于stack exchange，提问作者Profer