UNIX for Dummies Questions & Answers

i need a basic tutorial on running cron jobs. i have no clue where to even begin. the only solid info i have found thusfar is that i need a scheduler script in flat text format called a crontrab. ive seen what appear to be scripts, but have no idea if those posts are partial scripts (and other pertinent info).

purpose: i am using an xml parsing script to display user hwadlines.

need: bottom line instructions and detailed explanation.

i cannot use a script, even ask the right questions, without knowing 'something'. please post links, etc. so i can begin. im sure with the right start i can figure the better part of it out in a short amount of time.

thanks

Hi Hon,
I don't know any links off the top of my head but I am sure you can find some by searching the web. Two other resources I can think of are doing a man on both cron and crontab as well as buying a copy of "Essential System Administration". This is a really good resource for all kinds of basic unix info. Check out http://www.oreilly.com/catalog/esa2/.
The method I use to update cron is to do this:

crontab -l > cron.txt

This will output the cron jobs for the user you are logged in as into a file called cron.txt. You can vi cron.txt to add your entries and run:

crontab cron.txt

This will change the cron accordingly.
Hope this helps,
TioTony

Thank you TioTony for your help.

what im looking for is very basic instructions. please note: i am at the point of understand this as i was when i opened a perl script for the very first time (shudder). i dont understand coded lines and need step one. most info i find starts me off at what seems to be the middle. example: ive taken "vi cron.txt" to be a misspelling of "view cron.txt" but i cant even be sure of that!

"crontab -l > cron.txt " am i telnetting in and typing this or does this go in a file somewhere or something totally different?



thanks in advance to anyone who can help out!

(((i have no clue where to even begin.)))

Hi Hon!
I use a different variation of invoking cron. YOu are correct in that you need to be at the unix command prompt. From here I would type:

crontab -e

This should open up your specified cron file for this user to edit with the vi editor (vi is a standard unix editor). The layout for entering entries can be seen in the man pages, but generally it goes like this:

minute hour monthday month weekday command

for example to run 'test.sh' at 7:30 am on Sunday ...

30 07 * * 0 $WHATEVER_LOCATION/test.sh

asterisks indicate that it occurs all the time in that entry (in this case, every month day, and every month.)

Just be sure when scheduling that the person invoking the script has the correct permissions on the script. And also be sure to export any variables that the script might need. (for example, I have Oracle scripts that run sql based reports, in order to invoke sqlplus, I have to source its run location, database name, etc or else you will get errors).

Hope this helps!

im getting there! thanks to both for the help

try these helpful links......this is where i was educated

http://www.superscripts.com/tutorial/crontab.html
http://www.nerc-online.com/support/www/crontab.html

------Jeff

thank you very much. those tuts helped tremendously. i have root access on one server on which im hosted, but one other i do not. on the first i set up my file and went back to edit it the correct way after reading the tut. on the oddball-with-many-limits server i am using a script that simulates cron. the script can be found at http://www.smartCGIs.com and is appropriately called Fake Cron.

thanks again!