Test a weekly cron job

Question

I have a    bin bash file in cron week directory   Is there a way to test if it works  Can t wait 1 week  I am on Debian 6 with root

User · Answer

The solution I am using is as follows    Edit crontab use command  crontab -e  to run the job as frequently as    needed  every 1 minute or 5 minutes  Modify the shell script which should be executed using cron to prints    the output into some file  e g  echo  Working fine     output txt  Check the output txt file using the command   tail -f output txt     which will print the latest additions into this file  and thus you can track the execution of the script

User · Answer

None of these answers fit my specific situation  which was that I wanted to run one specific cron job  just once  and run it immediately   I m on a Ubuntu server  and I use cPanel to setup my cron jobs   I simply wrote down my current settings  and then edited them to be one minute from now  When I fixed another bug  I just edited it again to one minute from now  And when I was all done  I just reset the settings back to how they were before   Example  It s 4 34pm right now  so I put 35 16        for it to run at 16 35   It worked like a charm  and the most I ever had to wait was a little less than one minute   I thought this was a better option than some of the other answers because I didn t want to run all of my weekly crons  and I didn t want the job to run every minute  It takes me a few minutes to fix whatever the issues were before I m ready to test it again  Hopefully this helps someone

User · Answer

After messing about with some stuff in cron which wasn t instantly compatible I found that the following approach was nice for debugging   crontab -e             path to prog var1 var2  amp  gt  gt  tmp cron debug log log   This will run the task once a minute and you can simply look in the  tmp cron debug log log file to figure out what is going on   It is not exactly the  fire job  you might be looking for  but this helped me a lot when debugging a script that didn t work in cron at first

User · Answer

A wee bit beyond the scope of your question    but here s what I do   The  how do I test a cron job   question is closely connected to  how do I test scripts that run in non-interactive contexts launched by other programs     In cron  the trigger is some time condition  but lots of other  nix facilities launch scripts or script fragments in non-interactive ways  and often the conditions in which those scripts run contain something unexpected and cause breakage until the bugs are sorted out    See also  https   stackoverflow com a 17805088 237059    A general approach to this problem is helpful to have   One of my favorite techniques is to use a script I wrote called  crontest    It launches the target command inside a GNU screen session from within cron  so that you can attach with a separate terminal to see what s going on  interact with the script  even use a debugger   To set this up  you would use  all stars  in your crontab entry  and specify crontest as the first command on the command line  e g              crontest  command to be tested --param1 --param2   So now cron will run your command every minute  but crontest will ensure that only one instance runs at a time    If the command takes time to run  you can do a  screen -x  to attach and watch it run    If the command is a script  you can put a  read  command at the top to make it stop and wait for the screen attachment to complete  hit enter after attaching   If your command is a bash script  you can do this instead             crontest --bashdb  command to be tested --param1 --param2   Now  if you attach with  screen -x   you ll be facing an interactive bashdb session  and you can step through the code  examine variables  etc      bin bash    crontest   See https   github com Stabledog crontest for canonical source     Test wrapper for cron tasks   The suggested use is       1  When adding your cron job  use all 5 stars to make it run every minute    2  Wrap the command in crontest                Example         crontab -e                  usr local bin crontest  HOME bin my-new-script --myparams      Now  cron will run your job every minute  but crontest will only allow one    instance to run at a time         crontest always wraps the command in  screen -d -m  if possible  so you can    use  screen -x  to attach and interact with the job          If --bashdb is used  the command line will be passed to bashdb   Thus you    can attach with  screen -x  and debug the remaining command in context       NOTES      - crontest can be used in other contexts  it doesn t have to be a cron job          Any place where commands are invoked without an interactive terminal and         may need to be debugged        - crontest writes its own stuff to  tmp crontest log       - If GNU screen isn t available  neither is --bashdb    crontestLog  tmp crontest log lockfile   if    -d  var lock     then echo  var lock crontest lock  else echo  tmp crontest lock  fi   useBashdb false useScreen    if which screen  amp  gt  dev null  then echo true  else echo false  fi   innerArgs      screenBin   which screen 2 gt  dev null   function errExit       echo   -err-        tee -a  crontestLog  gt  amp 2    function log       echo   -stat-       gt  gt   crontestLog    function parseArgs       while      -z  1     do         case  1 in             --bashdb                  if    useScreen  then                     errExit  --bashdb invalid in crontest because GNU screen not installed                  fi                 if   which bashdb  amp  gt  dev null  then                     errExit  --bashdb invalid in crontest  no bashdb on the PATH                  fi                  useBashdb true                                --                  shift                 innerArgs                      return 0                                                   innerArgs                      return 0                            esac         shift     done    if    -z   sourceMe     then       Lock the lockfile  no  we do not wish to follow the standard       advice of wrapping this in a subshell       exec 9 gt  lockfile     flock -n 9    exit 1        Zap any old log data         -f  crontestLog     amp  amp  rm -f  crontestLog      parseArgs           log  crontest starting at   date       log  Raw command line          log  Inner args          log  screenBin   screenBin      log  useBashdb     if  useBashdb  then echo YES  else echo no  fi        log  useScreen     if  useScreen  then echo YES  else echo no  fi           Were building a command line      cmdline           If screen is available  put the task inside a pseudo-terminal       owned by screen   That allows the developer to do a  screen -x  to       interact with the running command      if  useScreen  then         cmdline   screenBin -D -m       fi        If bashdb is installed and --bashdb is specified on the command line        pass the command to bashdb   This allows the developer to do a  screen -x  to       interactively debug a bash shell script      if  useBashdb  then         cmdline   cmdline   which bashdb        fi        Finally  append the target command and params      cmdline   cmdline  innerArgs       log  cmdline   cmdline          And run the whole schlock       cmdline       res         log  Command result   res        echo   -result-    if     res -eq 0     then echo ok  else echo fail  fi    gt  gt   crontestLog        Release the lock      9 lt  amp - fi

User · Answer

What about putting it into cron hourly  waiting until the next run of hourly cron jobs  then removing it   That would run it once within an hour  and in the cron environment   You can also run   your script  but that won t have the same environment as under cron

User · Answer

I d use a lock file and then set the cron job to run every minute   use crontab -e and            path to job  That way you can just keep editing the files and each minute they ll be tested out  Additionally  you can stop the cronjob by just touching the lock file          bin sh     if   -e  tmp cronlock       then         echo  cronjob locked          exit 1     fi      touch  tmp cronlock      lt    do your regular cron here      gt      rm -f  tmp cronlock

User · Answer

Aside from that you can also use    http   pypi python org pypi cronwrap   to wrap up your cron to send you an email upon success or failure

User · Answer

I normally test by running the job i created like this   It is easier to use two terminals to do this   run job      jobname sh   go to      var log and run    run the following    tailf  var log cron   This allows me to see the cron logs update in real time  You can also review the log after you run it  I prefer watching in real time   Here is an example of a simple cron job  Running a yum update        bin bash YUM  usr bin yum  YUM -y -R 120 -d 0 -e 0 update yum  YUM -y -R 10 -e 0 -d 0 update   Here is the breakdown    First command will update yum itself and next will apply system updates   -R 120   Sets the maximum amount of time yum will wait before performing a command  -e 0   Sets the error level to 0  range 0 - 10   0 means print only critical errors about which you must be told   -d 0   Sets the debugging level to 0 - turns up or down the amount of things that are printed   range  0 - 10    -y   Assume yes  assume that the answer to any question which would be asked is yes  After I built the cron job I ran the below command to make my job executable    chmod  x  etc cron daily jobname sh    Hope this helps  Dorlack

User · Answer

Just do what cron does  run the following as root   run-parts -v  etc cron weekly       or the next one if you receive the  Not a directory  -v  error   run-parts  etc cron weekly -v   Option -v prints the script names before they are run

User · Answer

sudo run-parts --test  var spool cron crontabs    files in that crontabs  directory needs to be executable by owner - octal 700  source  man cron and NNRooth s

User · Answer

I m using Webmin because its a productivity gem for someone who finds command line administration a bit daunting and impenetrable       There is a  Save and Run Now  button in the  System   Scheduled Cron Jobs   Edit Cron Job  web interface     It displays the output of the command and is exactly what I needed

[linux] Test a weekly cron job

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