Getting Started

As of V5R3, you can declare up to five files in a single CL program. In this utility, I declare two files and do two loops. You will need to download two utilities written by Mike Sansoterra, RUNSQL and LOOKUP. You'll also have to download the source code for my utility from the MC Press Web site. The DDS for the database file is provided, but to create the flat file, see the compile instructions at the top of the CLP.

Walking Through the Utility

At the beginning of the program, you will notice that two files are declared. The flat file will receive the data extracted from the Qshell command. This file cannot exist in QTemp because Qshell cannot access QTemp. The other file is simply for ease of querying the data.

Start by using Qshell to list all the stream files in the IFS folder.

CHGVAR VAR(&CMD) VALUE('cd' *BCAT &IFSPATH *BCAT '&&' +    
      *BCAT 'ls -lTtr >' *BCAT '/qsys.lib/' *CAT &FILELIB +
      *TCAT '.lib/ifsdirf.file/ifsdirf.mbr')               

Notice that there is a double ampersand (&&) after the second *BCAT. This simply means to run the next command if the preceding command was successful.

Now let's break down the Qshell command itself ('ls –lTtr'). The 'ls' (lowercase letter L) tells Qshell to list the contents of a directory. After the dash, the second lowercase L tells the program to produce a long listing that gives more detail about each file. This will allow you to be creative in selecting which records you would like to select to delete later in the program. The uppercase T tells Qshell to display full date and time information. The lowercase T tells Qshell to sort by date and time instead of alphabetically by file name. The last letter, the lowercase R, reverses the sort order to descending by date and time.

Now we get into the first loop of the program with a command label of LOOP1. You will notice a parameter on the RCVF command called OPNID. This is used to distinguish the fields between the two files that were declared. You must use a name of 10 characters or fewer, which will be appended with an underscore (_) in front of the field names much like SQL alias names. Below is a sample of what the flat file looks like after the Qshell command has been executed.

total: 14.472 megabytes                                                            
-rwxrwxrwx  1 DOWNING   0    617652 May  1 08:14:52 2006 BSALOAD.CSV   
-rwxrwxrwx  1 DOWNING   0    208139 May  4 10:53:33 2006 OCPORPT04P.CSV
-rwxrwxrwx  1 DOWNING   0    265547 May  4 10:54:41 2006 OCPORPT05P.CSV

After the file is loaded, the program goes to the command labeled NEXT. Here is where we use Mike's RUNSQL utility. I used this to delete the first record in the file with the total size information as shown above. I am just doing a little housecleaning before I import the needed data from the flat file into the database file.

In the second RUNSQL command, I use a user-defined function (UDF) called MONTHNBR, which I have provided in the downloadable source. This UDF takes either a fully spelled out month (JANUARY) or a month name abbreviation (JAN) and returns a '1' for month number one. This is used to build a numeric-style date such as 01/01/07. Take some time to research UDFs and try using them in some of your other applications.

Mike's LOOKUP utility is similar to the RUNSQL utility except that LOOKUP allows you to do a SELECT into a return variable to use later in the program. I use it to get the minimum date in my file.

In the third RUNSQL command, I delete the files from the database file where the month and year do not match the minimum date I selected in the LOOKUP command. This is where you can be creative and select just your own files, certain file types, certain file sizes, or whatever you may choose. Depending on the authorities set up on your system, you may not have authority to another programmer's files, so you might choose to delete your own files and a certain date range.

Finally, the last loop, LOOP2, will read through the remaining records in your database file and use the RMVLNK command to delete the files out of the selected IFS folder.

Delete Away!

This utility gives you a lot of versatility on what files you select and how you select them to be deleted from the folder. It also introduces you to two new utilities, RUNSQL and LOOKUP, which you can use in many other applications. You also have a chance to learn more about Qshell, UDFs, SQL, and multiple file declarations. Have fun deleting those old files!

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