File Handling In Rexx

File handling or Dataset Handling in REXX is done Using it's EXECIO function's.


To write a Dataset in Rexx

Write Link


To Read a Dataset in Rexx

Read Link

How To Write a Dataset In Rexx

Writing a file in REXX is a kind of a easy job . Generally we have to store all the lines which we want to WRITE in an array. And Once we are done with what we want to write in an array we can write it into a PS or member of PDS.

• Initializing  (i.e Array.="") the array which we are going to write is a very good practice.
• At times you end up with writing errors if we don't initialize the array.
• You can load any number of arrays and write one array in one or more dataset by repeating the dataset syntax for various PS or PDS.

       

                      "ALLOC FI(LNAME) DA('MY.PS.WRITE') SHR"
                      "EXECIO * DISKW LNAME(STEM ARRAY. FINIS"
                      "FREE FI(LNAME)"

      • Where LNAME is the logical name of the dataset 'MY.PS.WRITE'.

      •  Finally it is a good practice to free the file you are writing.

      •  Now you could also write the same array into a different Dataset in the same REXX program.

                      "ALLOC FI(LNAME) DA('MY.PS.WRITE.NEW') SHR"
                      "EXECIO * DISKW LNAME(STEM ARRAY. FINIS"
                      "FREE FI(LNAME)"

How To Read a Dataset In REXX

File handling is REXX is one of the most easiest thing to do. The file reading in rexx is done in a line by line reading format. For example this the below happens when a dataset in read in rexx

• Each line of the Dataset is stored in each subscript in a array . For example array.1 will have the first line of the dataset and array.2 will have the second one and so on.
• The total number of lines read will be available in array.0 variable which will be used to used to loop through the lines.
• Below is the example how to read a dataset 'MY.PS.READ' into array.

           

                      "ALLOC FI(LNAME) DA('MY.PS.READ') SHR"
                      "EXECIO * DISKR LNAME(STEM ARRAY. FINIS"
                      "FREE FI(LNAME)"

      • Where LNAME is the logical name of the dataset 'MY.PS.READ'.

      •  Finally it is a good practice to free the file you are reading

      •  Now if you want to display all the contents within the array can use this code.

                            DO I=1 TO ARRAY.0

                                  SAY ARRAY.I

                                         END



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How To Create a Dataset In Rexx

Hi folks,

It becomes necessary for us to create dataset for many programming purpose.As creating a dataset using rexx is easy , I am just placing the code to create dataset in rexx.

Due to Security issues we are often allowed to create datasets only starting with the our TSO sign on ID. Thats's the reason why i have created the dataset with the TSO logon id and then i have later altered to the Dataset name which we actually wanted.

/*************** REXX at REXXPROGRAMMING.BLOGSPOT.COM***************/
USER_ID = USERID()
ACTUAL_PDS_NAME ='ACTUAL.PDS,NAME'
PDS_NAME_TO_ALTERED= USER_ID||".PDS.NAME "
   "ALLOCATE DATASET('"PDS_NAME_TO_ALTERED"') CATALOG LRECL (80),           BLKSIZE(27920) RECFM(F B) DSORG(PO) TRACKS SPACE(1 5) DIR(30)"

         "ALTER '" PDS_NAME_TO_ALTERED "' NEWNAME('"ACTUAL_PDS_NAME"')"

EXIT.


This Should result in Creating a Dataset Named 'userid(tso id).pds.name' and altered to 'actual.pds.name'



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How To Check If a Dataset Already Exist In REXX Programming

Folks,

       At times we are in need to know if few datasets already exist in HOST.It's a very easy piece of code that would help us to know if dataset exist or not.


/***************REXX AT REXXPROGRAMMING.BLOGSPOT.COM***************/

 IF SYSDSN("dataset.name") = "OK" THEN
    DO
            SAY "DATASET EXISTING"
    END
   ELSE
   DO
SAY "DATASET DOES NOT EXIST"

END
EXIT

where 'dataset,name' is the dataset to be checked for existence.



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Rexx Program To Display a ISPF PANEL

hi folks,


This a sample piece of Code how to display a ISPF Panel Using Rexx.


/******************* REXX AT REXXPROGRAMMING.BLOGSPOT.COM*************************/

 ADDRESS ISPEXEC                                                     

 "LIBDEF ISPPLIB DATASET ID('YOUR.PANELPDS.NAME')"  

ADDRESS ISPEXEC                

 "DISPLAY PANEL(PANELNAME)"

EXIT

Where PANELNAME is the member inside YOUR.PANELPDS.NAME.

How To Call ISPF Panels From REXX PROGRAM

Hi folks,


      Create a panel and keep it in a separate PDS which is called 'ISPF PANEL LIBRARY'

In the Rexx program add the library using this piece of code

/*************** Rexx At REXXPROGRAMMING.BLOGSPOT.COM***************/

"ispexec libdef ispplib library id (PANEL.PDS.NAME)"

After this you can call using

"ispexec display panel(PANEL.MEMBER.NAME)"


Exit


Where


PANEL.PDS.NAME              - Is the PDS name where the panel actually exist
PANEL.MEMBER.NAME    - The member name  inside PANEL.PDS.NAME

Differences Between Mainframe rexx and Regina Rexx

There is Not much differences between Regina rexx and mainframe rexx, A person able to program any one of the rexx program could manage both and use both the forms uniformly.


Both the forms has its own advantages. Mainframe rexx has more powerful tools than Regina rexx. Take for example it can submit jcl's, Create or delete  PS,PDS and could execute any TSO command . In future posts i will be explaining all the possible commands in both Regina and mainframe rexx.

Rexx Programming Basics

Hi Folks,


              To start from the scratch . Rexx programming is done to basically automate few regular and frequent operations on data. Not restricting to Main Frame it can be used to create tools for any language. A simple example would be if there is a need to change a pin code starting with 145 to 551 which is repeated a 1000 times in your data. You can write a Rexx tool to change everything in seconds. But there's lot interesting in Rexx to do. One of the foremost thing to note in rexx is there is no kind of a syntax , data type declaration in Rexx. So its easy to learn learn. So common lets REXX!!!




Rexx Language is NOT case sensitive.Rexx Programming is mostly used in conversions , SQL Query generation with a set of input's you have. To write a set of mathematical instructions and execute it for all the data you. Going forward I will Post basic Program's in Rexx. And the various places you can use rexx and benefit using this very easy programming language.