Gerald Wheeler wrote: > >>>> Rob Dixon <[EMAIL PROTECTED]> 4/3/2008 3:49 PM >>> > Gerald Wheeler wrote: >> Need some assistance: >> A script that writes (will usually appends) 8 records >> (rows/lines/whatever) to a flat file >> problem: >> If there are NO records with the date (date format: 03-Apr-08) >> of the "incoming data" I want to write/append these records to the > file >> If there are existing records with the date (03-Apr-08) of the >> "incoming data" I want to simply exit the script. >> The script will run multiple times per day, everyday. >> Sample input (8 records) >> "use these values(1234,'03-Apr-08',1234.56);" >> "use these values(1357,'03-Apr-08',1234);" >> "use these values(2468,'03-Apr-08',333666);" >> "use these values(4567,'03-Apr-08',3456);" >> "use these values(2233,'03-Apr-08',3234.56);" >> "use these values(3356,'03-Apr-08',2234);" >> "use these values(5577,'03-Apr-08',633666);" >> "use these values(5577,'03-Apr-08',2456);" >> >> Using the date as the determining factor as to write/append or > simply >> exit the script because the data already exist from a prior run, how > is >> the best way to do this and how do I easily compare dates in Perl > > If this data is at all critical then you need to account for the > possibility that the program fails before it completes. For instance, > if > only the first line of many with the new date is appended and then the > program dies, all subsequent runs will find a record with the current > date and assume it is complete. > > ..... Let's assume the transaction completes..........
If you're certain that that's safe, then I can't disagree. But if you find you're losing records once or twice a year then remember what I advised. > Does your data format support comments? If so then writing a comment > line at the end of each run's additions will show that it has > completed. > If a later run finds that there is no closing comment then it should > delete all entries for that date and try to rewrite them. > > ... Not necessary ....... w/abv assumption > > There is no need to compare dates. Your program is already generating > a > date string, and it can simply check to see if the tail records of the > data file contain that string. > > .... OK... so how would I use the system date "sysdate" to check > against the date of the records in the file.. > That's what I really need to know how to do.. ............ OK, your program generates lines like use these values(5577,'03-Apr-08',2456); and somewhere it generates the text string '03-Apr-08' to produce those lines. Suppose it is stored in a variable called $date_string. You need to read through the file to see if the condition $line =~ /$date_string/ or index $line, $date_string >= 0 is true for any line in the file. If the file is expected to become significantly large, then the File::ReadBackwards module may help you to start reading the file from the end. -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/
