Crontab周四定时任务异常求助：配置周四23:55执行重启脚本却在周一或周二触发

Hey there, let's get this sorted out quickly—your current crontab entry is running every single day at 11:55 PM, which explains why it's triggering on Mondays/Tuesdays instead of only Thursdays.

The Root Cause #

Crontab follows a 5-field schedule structure (plus the command to run):

分钟 小时 日 月 星期几 命令

Your existing entry 55 23 * * * /usr/html/scheduler/restart.sh > /usr/html/scheduler/file.log uses a * in the 5th field (day of week), which translates to "every day". That's why it's firing daily instead of just your intended Thursdays.

The Correct Crontab Entry #

To restrict the task to only Thursdays, set the 5th field to 4 (note: in most crontab implementations, 0=Sunday, 1=Monday, ..., 4=Thursday, 7=Sunday). Here's the fixed line:

55 23 * * 4 /usr/html/scheduler/restart.sh >> /usr/html/scheduler/file.log 2>&1

I added two small but useful tweaks:

• Changed > to >> to append log entries instead of overwriting the file each time (so you can keep a full history of runs)
• Added 2>&1 to capture both standard output and error messages in the log—this makes it way easier to debug if the script fails silently

Additional Troubleshooting Steps #

If you still hit issues after updating the entry:

• Confirm the crontab was saved properly with crontab -l (this lists all your scheduled tasks)
• Check system cron logs (usually at /var/log/cron or /var/log/syslog) to verify the task is being triggered on Thursdays
• Ensure your script has execute permissions: run chmod +x /usr/html/scheduler/restart.sh
• Test the script manually first to confirm it works as expected: /usr/html/scheduler/restart.sh

内容的提问来源于stack exchange，提问作者Elaine Byene