Using IBM Application Development Tools for z/OS and OS/390

Chapter 2. Introducing File Manager 41

2.1.10 Replace a string in a specific location in a file

If you need to unconditionally replace a string in one location of a file, you can use this utility.

The code to perform this function with File Manager is shown in Example 2-11.

Example 2-11 File Manager string replace batch step

//*

//* FILE MANAGER BATCH: REPLACE A STRING IN A SPECIFIC LOCATION

//*

//STEP01 EXEC PGM=FMNMAIN

//STEPLIB DD DSN=FMN.V4R1M0.SFMNMOD1,DISP=SHR

//* DD DSN=IGY.SIGYCOMP,DISP=SHR

//SYSPRINT DD SYSOUT=*

//FMNTSPRT DD SYSOUT=*

//SYSTERM DD SYSOUT=*

//EDITFILE DD DISP=OLD,DSN=YOUR.FILE.TO.EDIT

//SYSIN DD *

$$FILEM DSU INPUT=EDITFILE,

$$FILEM PROC=*

OUTREC=OVERLAY(‘vaLUE’,INREC,11)

/+

What is happening in this step

The File Manager program keyword DSU invokes the Data Set Update utility, which is only

available in batch.

The utility reads records sequentially from the input file. When File Manager processes them,

it uses two built-in REXX variables, INREC and OUTREC to refer to the input and output records.

In this case, we use a standard REXX function, OVERLAY, to indicate a string should be placed

at a specific location. This is assigned to the output record that is written to the file a portion of

which is shown in Example 2-12.

Example 2-12 Output from string replace batch job

IBM File Manager for z/OS and OS/390

$$FILEM DSU DSNIN=DAVIN6.FILE.TO.EDIT,

$$FILEM PROC=*

13 record(s) read

13 record(s) updated

2.1.11 Copy selected variably blocked records to another file

If you need to copy selected records from a production file to a test file, you can use this

utility. In this case there are multiple criteria and there is only one output file. This example

also demonstrates how File Manager processes new file allocation and variable blocked

records.

The steps necessary to perform this function using REXX with File Manager follow. First you

select option 3.3 from the main FM menu, producing a panel as shown in Figure 2-21.

42 Using IBM Application Development Tools for z/OS and OS/390

Figure 2-21 Option selection from main File Manager panel

By selecting Use proc with the generic ‘*’ and pressing Enter, you can now enter record

selection criteria for the copy. In this example we are selecting only those records with either

a C, G, L, M, or S in column 3, as shown in Figure 2-22.

Figure 2-22 Record selection criteria

By pressing Enter, followed by PF3, you can now enter the name of the file to which the data

is to be copied. In this example, we are dynamically defining a new file (SEQFILEX) with the

same characteristics as the input file. These steps are shown in Figure 2-23, Figure 2-24, and

Figure 2-25.

Chapter 2. Introducing File Manager 43

Figure 2-23 Name of file to be copied to 1 of 3

Figure 2-24 Name of file to be copied to 2 of 3

44 Using IBM Application Development Tools for z/OS and OS/390

Figure 2-25 Name of file to be copied to 2 of 3

Since we selected Batch execution for this Copy job, we are presented with the JCL as

shown in Example 2-13.

Example 2-13 JCL for batch

//FILEMGR EXEC PGM=FMNMAIN

//STEPLIB DD DSN=FMN.V4R1M0.SFMNMOD1,DISP=SHR

//* DD DSN=IGY.SIGYCOMP,DISP=SHR

//SYSPRINT DD SYSOUT=*

//FMNTSPRT DD SYSOUT=*

//SYSTERM DD SYSOUT=*

//SYSIN DD *

$$FILEM DSC DSNIN=REDBK2.TEST.SEQFILE,

$$FILEM POSITION=0,

$$FILEM DISP=MOD,

$$FILEM DSNOUT=REDBK2.TEST.SEQFILEX,

$$FILEM PROC=*

*FASTPROC

INCLUDE COND=(3,1,SS,EQ,C'C,G,L,M,S')

/+

Submitting this job, we see the successful execution report as shown in Example 2-14.

Example 2-14 Successful completion

IBM File Manager for z/OS

$$FILEM DSC DSNIN=REDBK2.TEST.SEQFILE,

$$FILEM POSITION=0,

$$FILEM DISP=MOD,

$$FILEM DSNOUT=REDBK2.TEST.SEQFILEX,

$$FILEM PROC=*

67 record(s) read

20 record(s) successfully copied

Chapter 2. Introducing File Manager 45

Alternatively, we could have used a REXX procedure to obtain the same result. For this

method, we coded the procedure as shown in Figure 2-26. Remember, though, that the

performance when processing large data sets is significantly better if DFSORT can be used.

Figure 2-26 REXX procedure

Following this through, we see JCL created as shown in Example 2-15.

Example 2-15 JCL created

//FILEMGR EXEC PGM=FMNMAIN

//STEPLIB DD DSN=FMN.V4R1M0.SFMNMOD1,DISP=SHR

//* DD DSN=IGY.SIGYCOMP,DISP=SHR

//SYSPRINT DD SYSOUT=*

//FMNTSPRT DD SYSOUT=*

//SYSTERM DD SYSOUT=*

//SYSIN DD *

$$FILEM DSC DSNIN=REDBK2.TEST.SEQFILE,

$$FILEM POSITION=0,

$$FILEM DISP=MOD,

$$FILEM DSNOUT=REDBK2.TEST.SEQFILEX,

$$FILEM PROC=*

IF CO(FLD(3,1),C,G,L,M,S) THEN

RETURN

ELSE

RETURN 'DROP'

/+

Successful completion of the job is shown in Example 2-16, with identical results. Note that

for a job such as this, particularly when working with a large file, DFSORT performance will be

significantly better than that of REXX.

Example 2-16 Successful completion

IBM File Manager for z/OS

$$FILEM DSC DSNIN=REDBK2.TEST.SEQFILE,

$$FILEM POSITION=0,

$$FILEM DISP=MOD,

$$FILEM DSNOUT=REDBK2.TEST.SEQFILEX,