我在 crontab 中有一个与计划相关的问题

Question

我正在尝试在 centos 中使用 crontab。如果我在 cron 选项卡中如下设置时间，它是如何工作的

* 5 * * *

Answer 1

摘自 crontab 手册页：

   The time and date fields are:

          field          allowed values
          -----          --------------
          minute         0-59
          hour           0-23
          day of month   1-31
          month          1-12 (or names, see below)
          day of week    0-7 (0 or 7 is Sunday, or use names)

   A  field  may  contain  an  asterisk  (*),  which  always  stands   for
   "first-last".

   Ranges of numbers are allowed.  Ranges are two numbers separated with a
   hyphen.  The specified range is inclusive.  For example, 8-11 for an

   Lists are allowed.  A list is a set of numbers (or ranges) separated by
   commas.  Examples: "1,2,5,9", "0-4,8-12".

   Step  values can be used in conjunction with ranges.  Following a range
   with "/<number>" specifies skips of  the  number's  value  through  the
   range.  For example, "0-23/2" can be used in the 'hours' field to specâ
   ify command execution for every other hour (the alternative in  the  V7
   standard  is  "0,2,4,6,8,10,12,14,16,18,20,22").   Step values are also
   permitted after an asterisk, so if specifying a job to be run every two
   hours, you can use "*/2".

   Names  can  also be used for the 'month' and 'day of week' fields.  Use
   the first three letters of the particular day or month (case  does  not
   matter).  Ranges or lists of names are not allowed.

   The  "sixth"  field  (the rest of the line) specifies the command to be
   run.  The entire command portion of the line, up to a newline or a  "%"
   character, will be executed by /bin/sh or by the shell specified in the
   SHELL variable of the cronfile.  A "%" character in the command, unless
   escaped  with a backslash (\), will be changed into newline characters,
   and all data after the first % will be sent to the command as  standard
   input.

   Note:  The day of a command's execution can be specified in the followâ
   ing two fields â 'day of month', and 'day of week'.  If both fields are
   restricted  (i.e.,  do not contain the "*" character), the command will
   be run when either field matches the current time.  For example,
   "30 4 1,15 * 5" would cause a command to be run at 4:30 am on  the  1st
   and 15th of each month, plus every Friday.

   EXAMPLE CRON FILE
   # use /bin/sh to run commands, no matter what /etc/passwd says
   SHELL=/bin/sh
   # mail any output to `paul', no matter whose crontab this is
   MAILTO=paul
   #
   CRON_TZ=Japan
   # run five minutes after midnight, every day
   5 0 * * *       $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
   # run at 2:15pm on the first of every month -- output mailed to paul
   15 14 1 * *     $HOME/bin/monthly
   # run at 10 pm on weekdays, annoy Joe
   0 22 * * 1-5    mail -s "It's 10pm" joe%Joe,%%Where are your kids?%
   23 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
   5 4 * * sun     echo "run at 5 after 4 every sunday"

我在 crontab 中有一个与计划相关的问题

I have a schedule related question in the crontab

linux

cron