我正在尝试在centos中使用crontab。如果我在cron选项卡中按如下方式设置时间，它是如何工作的
* 5 * * *
取自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"