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At command is used to execute commands at a specified time.
at a fairly complex method allows the use of a specified time. It can be accepted on the day of hh: mm (hours: minutes) formula specified time.
If the time has passed, then on the next execution. Of course, it is possible to use the midnight (midnight), noon (noon), teatime (tea time, usually 16:00) and other more obscure words to the specified time.
Users can also 12-hour clock, that is behind time plus AM (morning) or PM (afternoon) will be explained in the morning or afternoon. You can also specify the exact date command execution, specify the format for the month day (May day) or mm / dd / yy (month / day / year) or dd.mm.yy (day. Month, year). The specified date must follow the specified time in the back.
Described above are absolute timing method, in fact, also be able to use the relative timing method, which will soon be scheduled command execution is very good.
Specified as: now + count time-units, now is the current time, time-units is a unit of time, there can be minutes (min), hours (h), days (days), weeks (weeks). count the number of times, whether it is a few days or a few hours, and so on. More of a timing method is the direct use today (today), tomorrow (tomorrow) to specify the time to complete the command.
grammar
Options
-f: Specifies the task file contains specific instructions;
-q: Specifies the name of the new task queue;
-l: Displays a list of tasks to be performed;
-d: delete the specified task to be executed;
-m: Send E-mail task execution to the user upon completion.
parameter
Date Time: Specify task execution date and time.
Examples
17:00 After three days of execution / bin / ls:
[Root @ localhost ~] # at 5 pm+3 days
at> / bin / ls at> job 7 at 2016-01-08 17:00
17 o'clock tomorrow, output within the specified time to file:
[Root @ localhost ~] # at 17:20 tomorrow
at> date> /root/2016.log
at> job 8
at 2016-01-09 17:20
After the scheduled task set before us is not performed can atq command to view the system does not perform tasks:
[Root @ localhost ~] # atq
8 2016-01-06 17:20 a root
7 2016-01-08 17:00 a root
Delete a task that has been set:
[Root @ localhost ~] # atq
8 2016-01-06 17:20 a root
7 2016-01-08 17:00 a root
[Root @ localhost ~] # atrm 7
[Root @ localhost ~] # atq
8 2016-01-06 17:20 a root
Display the contents of the task has been set:
[Root @ localhost ~] # at -c 8
#! / Bin / sh
# Atrun uid = 0 gid = 0
# Mail root 0 umask 22 is omitted here n characters
date> /root/2016.log |
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