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Running the Operational Codes for the Brahmaputra

Running the Operational Codes for the Brahmaputra. Tom Hopson. Automatic (background) Job Processing: CRON.

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Running the Operational Codes for the Brahmaputra

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  1. Running the Operational Codes for the Brahmaputra Tom Hopson

  2. Automatic (background) Job Processing: CRON Cron is a time-base job scheduler in Unix-like computer operating systems. 'cron' is short for 'chronograph’. Cron enables users to schedule jobs (commands or shell scripts) to run automatically at a certain time or date. It is commonly used to perform system maintenance or administration, though its general purpose nature means that it can be used for other purposes, such as connecting to the Internet and downloading email.

  3. Crontab file: .---------------- minute (0 - 59) | .------------- hour (0 - 23) | | .---------- day of month (1 - 31) | | | .------- month (1 - 12) OR jan,feb,mar,apr ... | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat | | | | | * * * * * command to be executed There are several special entries, most of which are just shortcuts, that can be used instead of specifying the full cron entry: Entry Description Equivalent To @reboot Run once, at startup. None @yearly Run once a year 0 0 1 1 * @annually (same as @yearly) 0 0 1 1 * @monthly Run once a month 0 0 1 * * @weekly Run once a week 0 0 * * 0 @daily Run once a day 0 0 * * * @midnight (same as @daily) 0 0 * * * @hourly Run once an hour 0 * * * * Note: you may need to specify full paths of programs since SHELL (“dot” files) are not used by CRON

  4. More on crontab file execution timing: Some examples …

  5. First steps using Linux commands: Go to the directory cd /home/administrator/Desktop

  6. CRON file example: Create a file called, say, “cron_ex”, with: * * * * * echo "trying this out!" >> /home/administrator/Desktop/cron_test Then type: >crontab cron_ex (to install the CRON job) >crontab -l (to see if it is working in the CRON environment >date (to make sure a minute has passed) After a minute in your directory, you should see a file “cron_test” >cat cron_test (to see the output) Then type >crontab -r (to remove)

  7. Next, we want to use cron to control a computer program – In this case, an IDL program. But lets start with the basics first … Text edit: firstprog.pro In the file, type: print,'this is my program’ end Then, start idl Inside IDL, type: .r firstprog To exit IDL, type: exit … what do you get?

  8. CRON IDL example: Create a file called, say, “cron_idl”, with: * * * * * /usr/local/bin/idl</home/administrator/Desktop/infile_IDL Then create infile_IDL with: .rnew /home/administrator/Desktop/testcron.pro testcron exit And create testcron.pro with PRO testcron spawn,"echo 'trying this out!' > /home/administrator/Desktop/cron_test2" openw,1,’/home/administrator/Desktop/cron_test3' printf,1,'trying this out!' close,1 end

  9. Let’s run the program first to see what the output should look like: Start IDL: >idl To compile the procedure, type: >.r testcron To run the procedure, type: >testcron And exit idl >exit In a linux window, look at the file: >cat cron_test3 Now lets go back and have cron control this program …

  10. CRON IDL example: Create a file called, say, “cron_idl”, with: * * * * * /usr/local/bin/idl</home/administrator/Desktop/infile_IDL Then create infile_IDL with: .rnew /home/administrator/Desktop/testcron.pro testcron exit And create testcron.pro with PRO testcron spawn,"echo 'trying this out!' >> /home/administrator/Desktop/cron_test2" openw,1,’/home/administrator/Desktop/cron_test3' printf,1,'trying this out!' close,1 end And do as before to install … (then type >crontab -r to remove when finished)

  11. CRON IDL example 2: Now do as before with the file getRT.pro, to download satellite precip … first, let’s look at the file: ;--------------------------------------------------------------- ; program to download both 3-hr TRMM data ;--------------------------------------------------------------- PRO getRT,year,month,day,HISTDAYS gpcp3hrdir='/Users/hopson/WorldBank/Training_CWC_June2012/Labs/Day2/CRON/' gpcp3hrprefix='3B42RT.' gpcp3hrsuffix='.bin.gz' gpcp3hrftpsite= $ 'ftp://trmmopen.gsfc.nasa.gov/pub/merged/mergeIRMicro/' TRITIM=8 trihourly=['00','03','06','09','12','15','18','21'] ; note: added "-r" on Dec 30, 2006 to stop multiple file creation (i.e. *.1, *.2, etc.) ; that occurred around the beginning of Dec, 2006 ;***wgetcmd='/usr/bin/wget -N ' wgetcmd='/usr/local/bin/wget -N ' ; check last "HISTDAYS" days, including current day, to see if data exists if n_elements(year) eq 0 then begin HISTDAYS=1 ; number of past days to query if data retrieved ; get dates to check/download (earliest to latest) today=systime(/julian) endif else begin ; get dates to check/download (earliest to latest) today=JULDAY(month,day,year) endelse datenam=STRARR(HISTDAYS) for i=0,HISTDAYS-1 do begin caldat,(today-i),month,day,year stryear=strtrim(year,2) strmonth=strtrim(month,2) if month LT 10 then strmonth='0'+strtrim(month,2) strday=strtrim(day,2) if day LT 10 then strday='0'+strtrim(day,2) ;***datenam(i)=stryear+strmonth+strday ; latest to earliest datenam(HISTDAYS-1-i)=stryear+strmonth+strday ; earliest to latest endfor ; do for current and past days for i=0,HISTDAYS-1 do begin cd,gpcp3hrdir spawn,wgetcmd+'"'+gpcp3hrftpsite+gpcp3hrprefix+datenam(i)+'*'+'"' endfor RETURN end

  12. CRON IDL example 2: Now do as before with the file getRT.pro, and do as before to install … … and you’re now downloading NASA TRMM satellite precipitation data automatically! (then type >crontab -r to remove when finished) Note about the “wget” command: GNU Wget is a computer program that retrieves content from web servers, and is part of the GNU Project. Its name is derived from World Wide Web and get, connotative of its primary function. It currently supports downloading via HTTP, HTTPS, and FTP protocols, the most popular TCP/IP-based protocols used for web browsing.

  13. To run the forecasting codes: Go to the Desktop/practical cd /home/administrator/Desktop/practical Type the following in the “practical directory” >tar xspjSlf tarForecast.tbz2 Then go to the created Training/ directory Modify line 20 of the program se_fcstwkarma_w2s.pro to specify the working directory of the codes Start up IDL, then type >se_fcstwkarma_w2s,1 … and off it goes When finished, look at the plots in the “scratch” directory

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