April 4

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How to get a list of all files in an IFS folder

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By NickLitten

April 4, 2019

IBM i, CL, CLLE, programming, qshell, snippet
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Talking to a colleague this morning, we were discussing a vendor supplied series of spreadsheets (in CSV format) that his team needed to process.

“What’s the best way to read all the spreadsheets in an IFS folder so we can process them?”

bald bloke in the office

Well, we have a nice simple technique to use in a little CL (IBM i Control Language) program using QSHELL to list the files. Since we just want to read a list of all the *.CSV files in a folder, lets generate a simple list of those files into a temporary work file and read it, processing each one as we go.

List all files using QSHELL

QSH CMD('ls /home/littenn/*.csv -a | sort')

What are we saying here:

  • LS – List
  • /home/littenn – this is the folder that we want to list
  • *.csv – only list the comma separated value files (ie: something.csv)
  • -a – displays all files
  • | sort – give it in a nice sorted list please old chap

QSHELL is a funny old thing – even though it runs as part of your interactive session, it’s not really running as part of your interactive session. QSHELL runs as a background job which talks to your interactive session while its doing things. It uses three different files to communicate with you:

  • STDIN – the input file (or commands you want to run)
  • STDOUT – the output file ( or results from the input command)
  • STDERR – that’s right. The Error file. #oops

When you are using QSHELL, your running job becomes the terminal while the background QSHELL job launches into action waiting for input from the STDIN process. Anything you type into QSHELL gets placed in the STDIN pile, its processed and the results are placed in the STDOUT pile for you to enjoy. Or, obviously, the STDERR pile for you to not enjoy.

Example IBM i CLLE Program

This code snippet will override the response from QSHELL (STDOUT) direct into a file in QTEMP so we can read it. It will position itself into the folder that is being read. Use QSHELL to list the files – the response will be sent to our file. Then we read the file and do whatever magic we want with the files:

CMD – READ_DIR

CMD        PROMPT('Process files in IFS')

PARM       KWD(DIR) TYPE(CHAR) LEN(255) EXPR(YES) PROMPT('IFS Folder Name ie: /home/bob')

PARM       KWD(FILTER) TYPE(CHAR) LEN(30) DFT('.') EXPR(YES) PROMPT('Filter files (ie: *.CSV)')

CLLE – READ_DIR

/* READ_DIR - Read all CSV files in a given IFS dir and process them */
/* Program : READ_DIR                                                */
/* Author  : nick litten                                             */
/* Function: List selected files in an IFS DIR using QSHELL.         */
/*   Read that file and do some stuff with the files that are listed */
/* Compile Instructions.. 1: CRTPF FILE(QTEMP/READ_DIRF) RCDLEN(1000)*/                         /*                        2: CRTBNDCL PGM('library'/READ_DIR)        */
/*                           SRCFILE('library'/QCLLESRC)             */
/*                           SRCMBR(READ_DIR)                        */
/*                           REPLACE(*YES)                           */

PGM        PARM(&DIR &FILTER)
COPYRIGHT  TEXT('READ_DIR Ver.000')
DCLF       FILE(READ_DIRF) OPNID(FILE)
DCL        VAR(&DIR) TYPE(CHAR) LEN(255)  
DCL        VAR(&FILTER) TYPE(CHAR) LEN(30)
DCL        VAR(&PREVPATH) TYPE(CHAR) LEN(1024)  
DCL        VAR(&PPATHLEN) TYPE(DEC) LEN(7 0)
DCL        VAR(&QSHSTRING) TYPE(*CHAR) LEN(1024)
DCL        VAR(&CNLSTS) TYPE(CHAR) LEN(1) VALUE('0')  
DCL        VAR(&CRASHED) TYPE(LGL) VALUE('0')
DCL        VAR(&MSGID) TYPE(CHAR) LEN(7)  
DCL        VAR(&MSGDTA) TYPE(CHAR) LEN(256)
DCL        VAR(&MSGFIL) TYPE(CHAR) LEN(10)  
DCL        VAR(&MSGFLIB) TYPE(CHAR) LEN(10)
DCL        VAR(&MSGKEY) TYPE(CHAR) LEN(4)  
DCL        VAR(&RTNTYPE) TYPE(CHAR) LEN(2)
DCL        VAR(&SENDER) TYPE(*CHAR) LEN(80)

MONMSG     MSGID(CPF0000) EXEC(GOTO CMDLBL(CRASH)) /* Global monitor to pick non monitored error conditions */

/* Validate the directory name */
CHKLNK     OBJ(&DIR)  
MONMSG     MSGID(CPF0000) EXEC(DO)     
  SNDPGMMSG  MSGID(CPF9898) MSGF(QCPFMSG) 
  MSGDTA(' Directory' *BCAT &DIR *TCAT ' not found') 
  TOPGMQ(PRV)   MSGTYPE(ESCAPE)
ENDDO

/* collect the current directory we are pointed at - we will revert to this when we finish */

RTVCURDIR  RTNDIR(&PREVPATH) DIRNAMLEN(&PPATHLEN)

CD         DIR(&DIR)
MONMSG     MSGID(CPFA09C) EXEC(DO)
  SNDPGMMSG  MSGID(CPF9898) MSGF(QCPFMSG)
  MSGDTA('* Not authorised to directory' BCAT &DIR)
  TOPGMQ(PRV) MSGTYPE(*ESCAPE)
ENDDO

/* create a work file to hold the list of files that we load from the IFS directory */

DLTF       FILE(QTEMP/READ_DIRF)
MONMSG     MSGID(CPF0000)

CRTPF      FILE(QTEMP/READ_DIRF) RCDLEN(1000)

/* load the work file with a list of all the selected files in the IFS directory */

OVRDBF     FILE(STDOUT) TOFILE(QTEMP/READ_DIRF) OVRSCOPE(JOB)

CHGVAR     VAR(&QSHSTRING) VALUE('ls' *BCAT &DIR *TCAT '/' *TCAT &FILTER *TCAT ' -a | sort')

QSH        CMD(&QSHSTRING)

DLTOVR     FILE(STDOUT) LVL(*JOB)

IF         COND(&PPATHLEN *GT 0) THEN(CD DIR(&PREVPATH))

OVRDBF     FILE(READ_DIRF) TOFILE(QTEMP/READ_DIRF)
           POSITION(START) OVRSCOPE(CALLLVL)

/* read the list of files from the IFS folder we listed */
DOWHILE    COND(&CNLSTS = '0')
     RCVF       OPNID(FILE)
     MONMSG     MSGID(CPF0864) EXEC(LEAVE)
     /* field &READ_DIRF is the file name ie: something.csv    */
     SNDPGMMSG  MSGID(CPF9898) MSGF(QCPFMSG)
       MSGDTA('-- Doing something with' *BCAT &FILE_READ_DIRF)
       TOPGMQ(*PRV) MSGTYPE(*COMP)
    
     /* Add your logic here to do the IFS FILE magic */
     RTVJOBA    ENDSTS(&CNLSTS)
ENDDO

DLTOVR     FILE(READ_DIRF) LVL(*)

SNDPGMMSG  MSGID(CPF9898) MSGF(QCPFMSG) MSGDTA('Directory' *BCAT &DIR *TCAT ' has been read and files(' *TCAT &FILTER *TCAT ') have been processed') TOPGMQ(PRV) MSGTYPE(COMP)

RETURN

/* CRASH : Routine to handle unexpected errors */
  CRASH:
  IF         COND(&CRASHED) THEN(RETURN)
  CHGVAR     VAR(&CRASHED) VALUE('1')
  RCVMSG     MSGTYPE(*LAST) MSGDTA(&MSGDTA) MSGID(&MSGID) RTNTYPE(&RTNTYPE) MSGF(&MSGFIL) SNDMSGFLIB(&MSGFLIB)
  IF         COND(&RTNTYPE *EQ '15' *OR &RTNTYPE *EQ '17') THEN(DO) 
     SNDPGMMSG  MSGID(&MSGID) MSGF(&MSGFIL) MSGDTA(&MSGDTA) MSGTYPE(*DIAG)
  ENDDO
  ESCAPE:
  IF         COND(&PPATHLEN *GT 0) THEN(DO)
     CD         DIR(&PREVPATH)
     MONMSG     MSGID(CPF0000)
  ENDDO
  SNDPGMMSG  MSGID(CPF9898) MSGF(QCPFMSG) MSGDTA('* Program READ_DIR ended abnormally') MSGTYPE(*ESCAPE)
  RETURN
  ENDPGM: ENDPGM

I know I know….

That program just sort of grew as I put in my ear buds (not those poncy apple air pods) and got some programming grooove on.

When this runs it looks something like this:

How to get a list of all files in an ifs folder 1

Hope it helps someone 🙂

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