1. The difference between atd and crond task management programs
2. Specify to write the time into the testmail.txt file at 2023/03/29 19:00
3. Specify the time before the time point at 4:00 every day The system log information is backed up to a directory (/var/log/messages), and the log file name display format after backup is logfileYY-MM-DD HH-MM 4. Add two network cards to the current host, and bind the two network cards to
achieve NIC redundant operation.
1. The difference between atd and crond
atd is a single-execution routine work : it is only processed once and it ends;
crontab is a routine job that is executed cyclically : it needs to be executed every certain period.
2. Specify to write the time into the testmail.txt file at 2023/03/29 19:00
The entered time is the expiration time, you need to re-enter the valid time.
3. Specify to back up the system log information before this time point to a directory (/var/log/messages) at 4:00 a.m. every day, and the log file name display format after backup is logfileYY-MM-DD HH-MM
输入：0 4 * * * root cp /var/log/messages /logfile ' date +%F%R ' ; echo > /var/log/messages
4. Add two network cards to the current host, and bind the two network cards to realize network card redundancy operation.
Add two network cards
IP a ：
Activate network card:
IP a：
Add virtual network card team0: