Crontab timing in Ubuntu

Crontab timing in Ubuntu is a scheduled execution in linux. The following describes some problems I encountered when using crontab: 1. crontab-e [UserName]: Execute the text editor to set the time table crontab-r [UserName]: Delete the current time table crontab-l [UserName]: to list the current time table crontab-v [UserName]: to list the state of the user cron job crontab file: replace the original crontab file 2. when the crontab file is saved for the first time, a new file named after the current user name is created in the/var/spool/cron/crontabs folder, the content in the file is what you see when you edit crontab-e. 3. The statement ***** for adding a scheduled task to www.2cto.com indicates that the command is minute 1 ~ In column 1st of the daily and monthly command ~ 59 every minute, use * or */1 to indicate 2nd columns to indicate hour 1 ~ 23 (0 indicates 0 points) column 3rd indicates date 1 ~ 31 column 4th indicates the month 1 ~ 12 column ID No. 0 ~ 6 (0 indicates Sunday) The *** wget-q -- spider http: // localhost/xxx command to be run in column 6th. php calls a webpage every minute.