How to combine a scheduled task with a crontab

Wget and crontab combination scheduled task usage such as 0 4 *** wget -- spider http://www.google.com means to run wget at 04:00 every day ...... The following is a good introduction to crontab in the previous article: crontab task format ***** task minute-by-day, month, week, task, column 1st, minute 1 ~ 5 9 (0 indicates 0 points) 2nd columns hour 1 ~ 2 3 (0 indicates midnight) 3rd columns Day 1 ~ 3 1 4th columns Month 1 ~ 1 2 5th columns day of week 0 ~ 6 (0 indicates Sunday) Example of the command to be run in column 6th: 30 21 ***/apps/bin/cleanup. sh the above example indicates that c l e a n u p in the/a p s/B I n directory of 2 1: 3 0 every night. s h. 45 4, 10, 22 **/apps/bin/backup. sh the example above indicates that the 4: 4 5 run/a p s/B I n directory B a c k u p on the first, 1, 0, and 2 every month. s h. 10 1 ** 6, 0/bin/find-name "core"-exec rm {}/; the above example indicates 1 of every Saturday and Sunday: 1 0 run an f I n d command. 0, 30 18-23 ***/apps/bin/dbcheck. sh the above example indicates that every day 1 8: 0 0 to 2 3: run between 0 and every 3 0 minutes/a p s/B I n Directory d B c h e c k. s h. 0 23 ** 6/apps/bin/qtrend. sh the above example indicates that every Saturday's 11: 0 0 p m run/a p s/B I n directory q t r e n d. s h implements scheduled tasks in two ways: editing a file, loading with crontab one is to use crontab-e direct edit take effect I own an example every minute to a file into a bunch of characters First vi crontab1 # every minute echo char to file1-59 *** * echo 'date' "lj/n">/opt/lijie/lj.txt it is best to add comments to clarify the purpose of the current scheduled task and then load crontab crontab1 to the scheduled task crontab1. another type is crontab-e # every minute echo char to file1-59 *** echo 'date' "l J/n ">/opt/lijie/lj.txt date is enclosed in single quotes, indicating that if date is a command, it will be executed as a command. If you use date directly, the output is the string "date" instead of the execution result of the date command> appended to the end of the file,> directly overwrite the file. If crontab-e cannot be edited, the environment variable is not configured. Please go to vi/etc/profile and add EDITOR = viexport EDITORcrontab-l to list all scheduled tasks. to delete a scheduled task, comment out the corresponding scheduled task statement crontab-e, for example, delete the scheduled task I just defined # every minute echo char to file 1-59 **** echo 'date' "lj/n">/opt/lijie/lj.txt only needs # every minute echo char to file #1-59 **** e Cho 'date' "lj/n">/opt/lijie/lj.txt delete all scheduled tasks with crontab-r. Note: 1, if you use the crontab file to load a scheduled task, the scheduled task will be washed out. Therefore, if you want to add a scheduled task, you 'd better use crontab-e to add a scheduled task instead of the crontab file. 2. The crontab log file is/var/log/cron3. If you use crontab <filename> to set cron, be sure to pay attention to the file garbled. I encountered a problem. The/var/log/cron log shows Dec 28 11:34:00 TARGET CROND [13449]: (hnuc) CMD (/home/hnuc/shell/t. sh ^ M ~ M is garbled because: I used the cron file edited by editplus, and the carriage return line break symbol in it is dos rather than linux or unix. Here ^ M is actually a dos line break, which is parsed in linux.