How to run a script at a certain time on Linux

Question

I have a text file containing a specific date and time   I want to be able to run a script at the time specified in that file  How would you achieve that  Create another script that runs in background  sort of a deamon  and checks every second if the current time is matching the time in the file  Is there another way  The machine is a linux server   Debian wheezy  Thanks in advance

User · Answer

The at command exists specifically for this purpose  unlike cron which is intended for scheduling recurring tasks    at   cat file   lt  path to script

User · Answer

Cron is good for something that will run periodically  like every Saturday at 4am   There s also anacron  which works around power shutdowns  sleeps  and whatnot   As well as at   But for a one-off solution  that doesn t require root or anything  you can just use date to compute the seconds-since-epoch of the target time as well as the present time  then use expr to find the difference  and sleep that many seconds

User · Answer

Usually in Linux you use crontab for this kind of scduled tasks  But you have to specify the time when you  setup the timer  - so if you want it to be configurable in the file itself  you will have to create some mechanism to do that    But in general  you would use for example   30 1     5  path to script script sh   Would execute the script every Friday at 1 30  AM  Here   30 is minutes  1 is hour  next 2   s are day of month and month  in that order  and 5 is weekday

User · Answer

Look at the following   echo  ls -l    at 07 00   This code line executes  ls -l  at a specific time  This is an example of executing something  a command in my example  at a specific time   at  is the command you were really looking for  You can read the specifications here   http   manpages ubuntu com manpages precise en man1 at 1posix html http   manpages ubuntu com manpages xenial man1 at 1posix html  Hope it helps

[linux] How to run a script at a certain time on Linux?

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