The best solution for solving computer problems

Here, the slash is used in combination denote the areas specified at location x.

0-55/5 * * - * means that a human request is executed every five seconds (0, 5, 15, 10, …, 55).

  • Cron Format

  • Structure and generated crontab entries
  • Tips for learning Cron

  • Staff, rehearsal and delivery
  • Another scam: “@” syntax
  • Notes and warnings
  • cygwin – general cron setup method
  • Syntax

    Crontab users often ask what do you see, crontab arguments and the easiest way to create them… copy or just other people who knew the new master secret from the old Unix tradition :-)… No secret, to , Unfortunately, this will be a short introduction. .


    List of probably entries

    First, it is recommended to create my.cron (or similar) registry entries and then a few usage commands.

    present them. BUT this is definitely NOT recommended if you are in a multi-user environment as the above command is oftenChanges the user’s current cron job type to the contents of the my.cron file. ALWAYS do everything first, then a

    which flattens all existing entries and finally into its own my. edits redirects, changes and the cron file, not to mention reloading it. You

    Also note that this will change the cron word… BUT this assumes that the EDITOR environment variable has always been set to Nothing (if nothing is set, assume the default editor is likely to be vi).

    Authorization and niche format

    The structure entry itself looks like this: “If I want to launch my favorite world”, to “hello, at any time and add a file to it, would:

    # i.Possibility -(0 – 59)
    #|Â.- Lesson (0 – 23)Â |Â
    #|Â .- .of the .ceremony of the .month .(1 .– .31)Â .
    #|B .|B .| ..- Month OR (1-12) February, January, April…
    #|In March, |In | |.– weeks– Day (0 7) (Sunday=0 or maybe 7)
    #Â Â Â |Â OR Sun, Mon, Tue, Wed, Thu, Fri, Sat
    #| |inIn| | | .- |In team
    #|to | | |Â |
    # This is what My Hello World does – almost all protocols are standard designed
    * * * coomatches “Hello World” >>/home/jlauret/cron.log

    Pay attention, you, I indicated all the fields above so that they have their own meaning. In this position, the output to be redirected to run log.nala /home/jlauret/cron.log.marked
    Lines marked with “#” are comments. Make it a habit to leave an explanation section before you go to each cron entry to think about what it does – anything related to that might help (or other things if you’re the same DBA or using the same same group account) account. ).

    Tricks Name=”tricks”>Cron

    Although the crontab syntax is not checked in the man pages (a little unknown, especially on the men’s and women’s Linux sites), my man pages additionally contain excellent information about everything.


    Interestingly, Linux cron.accepts variable=value at the beginning of cron. you For example, you can use something like

    and this method can run any commands executed in crontab entries to bypass anything you may have set as a shell for the account. Another useful cron is mutable (if mailto doesn’t work mailto use MAIL as it depends a bit on the version of our proprietary service).

    Please send any bug reports or other output data (undirected log) that can be sent to Note that if you are NOT redirecting output to a first-class file, the default behavior is likely to redirect results to local history as usual. Be sure to remove STDOUT and hence stderr. In my example, the simple one mentioned above, only stdout was actually redirected to /home/jlauret/cron.log. You can change this redirect to your liking

    *some* 1 . 3 . echo *world" "hello >>&/home/jlauret/cron.log

    Range, Consistency, Or Steps

    The following syntax is usually available on your Linux (note that it may seem invalid, especially on older activation systems and cron-related versions)

    * * 7. * * 1-5 equals "Hello to World" 

    Open from Monday to Friday. The hyphen “-” turned out to be a more beautiful range of values this operator type. Similarly, the fold forward “/” step shows or repeats in each of An n. For example:

    */2 * 6 - . * echo "Hello world"
    0 * 0-23/2 ( space ) 4 . echo "Hello world"

    means “no”, you run the task at midnight, and then every two hours (of course, range and repeat are used here, you can just limit yourself to weekends). You can also specify a format to use with ANY version of cron):

    0 with 0,2,4,6,8,10,12 * * * means "Hello World"

    Repeat two month registrations from 0 (midnight) to 12 (noon) people. Trace combinations are also possible in the Per linux H example. Your ISP can specify fields 0-6, 20-23 (in your own favorite example, this time field example would have a hard time). Again, this hardly works with ATT, except for ( old) bsd crons. So if one wants to write standard cron item lists, beware of overly complex syntax, but if you work primarily on Linux, you should be very ashamed that you don’t need its convenience.

    Another Feature Of Name=”t_atsyntax”> Is The “@” Syntax

    Probably there are special keywordsova that cron takes into account directly, and it seems that these companies are converted to the “@” character. They are listed below

    @reboot: will start at about the same time as reboot after.
    @yearly: Second book of the same year, “0 1 zero 1*”.
    @annually: quickly indicates the time, i.e. 9 “0 1 *” unit.
    @monthly : runs once a month for just Null “0 1 * *”.
    @weekly: Runs almost a week later, i.e. “0 9 7 . * 0” .Once
    @daily: trigger by date, so 0 “0 * *” -.
    @hourly: does the dreaded “0 * * 1. *” once per second.

    # It’s better to delete Space C month
    @monthly via has /home/jlauret/bin/wipe -ersus c

    # Finish removing unnecessary files and editors /bin/rm -f weekly
    @weekly /cygdrive/c/Users/jlauret/.saves-*

    Reports to this case are in the form of @CMD tags. Again, don’t worry about people occasionally using the cron account, but you have been able to use these tags through Linux to do some repetitive tasks. @reboot is an abbreviation for a command that is sure to run once, i.e. after the computers are normally rebooted (this is a good time to make sure that the service is started on every reboot).load). = name “note” >

    Note Alerts

  • Remember that when a cron is run, the Que is NOT completely executed (i.e. your wonderful .cshrc or .bashrc is not always completely so original), you should not specify the full rewriteConnection value to use the command line. many. Especially if you’re using an alternative (Perl script or these annotations), which means your regular environment variables probably won’t be available in Perl scripts.
  • How Do I Delete A Cron Crontab Job?

    You can use the crontab inventory view to add, remove, or edit cron jobs with the following: crontab -e Edit the crontab view on the computer by creating it or if the item does not already exist. crontab Show -l crontab file with data. crontab Delete -l the current Crontab file. crontab Delete -i – Change the size of the monthly crontab file from the command line before deleting it.