ABAP File Operations: OPEN DATASET, READ, TRANSFER

Basic Commands

Command	Description
`OPEN DATASET`	Open file
`READ DATASET`	Read data from file
`TRANSFER`	Write data to file
`CLOSE DATASET`	Close file
`DELETE DATASET`	Delete file

Syntax

Open File

OPEN DATASET <filename>
  FOR { INPUT | OUTPUT | APPENDING | UPDATE }
  IN { TEXT MODE | BINARY MODE | LEGACY TEXT MODE }
  [ ENCODING { DEFAULT | UTF-8 | NON-UNICODE } ]
  [ WITH { SMART | NATIVE | UNIX | WINDOWS } LINEFEED ]
  [ MESSAGE <message> ].

Read/Write File

READ DATASET <filename> INTO <data> [ LENGTH <length> ].
TRANSFER <data> TO <filename> [ LENGTH <length> ].

Close/Delete File

CLOSE DATASET <filename>.
DELETE DATASET <filename>.

Examples

1. Write Text File

DATA: lv_file    TYPE string VALUE '/tmp/output.txt',
      lv_message TYPE string.

" Open file for writing
OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE
  ENCODING UTF-8
  MESSAGE lv_message.

IF sy-subrc = 0.
  " Write lines
  TRANSFER 'Line 1: Hello World' TO lv_file.
  TRANSFER 'Line 2: ABAP is great' TO lv_file.
  TRANSFER 'Line 3: End of file' TO lv_file.

  CLOSE DATASET lv_file.
  WRITE: / 'File written successfully'.
ELSE.
  WRITE: / 'Error:', lv_message.
ENDIF.

2. Read Text File

DATA: lv_file TYPE string VALUE '/tmp/input.txt',
      lv_line TYPE string.

OPEN DATASET lv_file FOR INPUT IN TEXT MODE
  ENCODING UTF-8.

IF sy-subrc = 0.
  " Read line by line
  DO.
    READ DATASET lv_file INTO lv_line.
    IF sy-subrc <> 0.
      EXIT.  " End of file
    ENDIF.

    WRITE: / lv_line.
  ENDDO.

  CLOSE DATASET lv_file.
ELSE.
  WRITE: / 'File could not be opened'.
ENDIF.

3. Read File into Table

DATA: lv_file  TYPE string VALUE '/tmp/data.txt',
      lv_line  TYPE string,
      lt_lines TYPE TABLE OF string.

OPEN DATASET lv_file FOR INPUT IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  DO.
    READ DATASET lv_file INTO lv_line.
    IF sy-subrc <> 0.
      EXIT.
    ENDIF.
    APPEND lv_line TO lt_lines.
  ENDDO.

  CLOSE DATASET lv_file.

  " Processing
  WRITE: / 'Lines read:', lines( lt_lines ).
ENDIF.

4. Write Table to File

DATA: lv_file  TYPE string VALUE '/tmp/export.txt',
      lt_lines TYPE TABLE OF string.

lt_lines = VALUE #(
  ( `Name;Age;City` )
  ( `Max;30;Berlin` )
  ( `Anna;25;Munich` )
  ( `Peter;35;Hamburg` )
).

OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  LOOP AT lt_lines INTO DATA(lv_line).
    TRANSFER lv_line TO lv_file.
  ENDLOOP.

  CLOSE DATASET lv_file.
  WRITE: / 'Exported:', lines( lt_lines ), 'lines'.
ENDIF.

5. Process CSV File

TYPES: BEGIN OF ty_customer,
         name TYPE string,
         age  TYPE i,
         city TYPE string,
       END OF ty_customer.

DATA: lv_file      TYPE string VALUE '/tmp/customers.csv',
      lv_line      TYPE string,
      lt_customers TYPE TABLE OF ty_customer,
      lt_fields    TYPE TABLE OF string.

OPEN DATASET lv_file FOR INPUT IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  " Skip header line
  READ DATASET lv_file INTO lv_line.

  " Read data lines
  DO.
    READ DATASET lv_file INTO lv_line.
    IF sy-subrc <> 0.
      EXIT.
    ENDIF.

    " Split line
    SPLIT lv_line AT ';' INTO TABLE lt_fields.

    IF lines( lt_fields ) >= 3.
      APPEND VALUE ty_customer(
        name = lt_fields[ 1 ]
        age  = CONV #( lt_fields[ 2 ] )
        city = lt_fields[ 3 ]
      ) TO lt_customers.
    ENDIF.
  ENDDO.

  CLOSE DATASET lv_file.
ENDIF.

" Display result
LOOP AT lt_customers INTO DATA(ls_cust).
  WRITE: / ls_cust-name, ls_cust-age, ls_cust-city.
ENDLOOP.

6. Create CSV Export

DATA: lv_file TYPE string VALUE '/tmp/export.csv',
      lv_line TYPE string.

DATA: lt_orders TYPE TABLE OF ty_order.

" Test data
lt_orders = VALUE #(
  ( id = 1 customer = 'Miller' amount = '100.50' )
  ( id = 2 customer = 'Schmidt' amount = '250.00' )
  ( id = 3 customer = 'Weber' amount = '75.25' )
).

OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  " Write header
  TRANSFER 'ID;Customer;Amount' TO lv_file.

  " Data lines
  LOOP AT lt_orders INTO DATA(ls_order).
    lv_line = |{ ls_order-id };{ ls_order-customer };{ ls_order-amount }|.
    TRANSFER lv_line TO lv_file.
  ENDLOOP.

  CLOSE DATASET lv_file.
ENDIF.

7. Read Binary File

DATA: lv_file   TYPE string VALUE '/tmp/image.png',
      lv_data   TYPE xstring,
      lv_buffer TYPE x LENGTH 1024,
      lv_length TYPE i.

OPEN DATASET lv_file FOR INPUT IN BINARY MODE.

IF sy-subrc = 0.
  DO.
    READ DATASET lv_file INTO lv_buffer LENGTH lv_length.
    IF sy-subrc <> 0.
      EXIT.
    ENDIF.

    " Append data
    CONCATENATE lv_data lv_buffer(lv_length) INTO lv_data IN BYTE MODE.
  ENDDO.

  CLOSE DATASET lv_file.
  WRITE: / 'Read:', xstrlen( lv_data ), 'bytes'.
ENDIF.

8. Write Binary File

DATA: lv_file TYPE string VALUE '/tmp/output.bin',
      lv_data TYPE xstring.

" Binary data (e.g., from DB or processing)
lv_data = 'A1B2C3D4E5F6'.

OPEN DATASET lv_file FOR OUTPUT IN BINARY MODE.

IF sy-subrc = 0.
  TRANSFER lv_data TO lv_file.
  CLOSE DATASET lv_file.
ENDIF.

9. Append to File (APPENDING)

DATA: lv_file TYPE string VALUE '/tmp/log.txt',
      lv_line TYPE string.

" Add date/time to log
lv_line = |{ sy-datum DATE = ISO } { sy-uzeit TIME = ISO }: New entry|.

OPEN DATASET lv_file FOR APPENDING IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  TRANSFER lv_line TO lv_file.
  CLOSE DATASET lv_file.
ENDIF.

10. Check and Delete File

DATA: lv_file TYPE string VALUE '/tmp/temp.txt'.

" Check if file exists (by opening)
OPEN DATASET lv_file FOR INPUT IN TEXT MODE ENCODING DEFAULT.

IF sy-subrc = 0.
  CLOSE DATASET lv_file.
  WRITE: / 'File exists'.

  " Delete file
  DELETE DATASET lv_file.

  IF sy-subrc = 0.
    WRITE: / 'File deleted'.
  ENDIF.
ELSE.
  WRITE: / 'File does not exist'.
ENDIF.

11. Read Directory

DATA: lv_dir      TYPE string VALUE '/tmp/',
      lt_files    TYPE TABLE OF string,
      lv_filename TYPE string.

" Open directory
CALL FUNCTION 'EPS_GET_DIRECTORY_LISTING'
  EXPORTING
    dir_name               = CONV eps2path( lv_dir )
  TABLES
    dir_list               = lt_files
  EXCEPTIONS
    invalid_eps_subdir     = 1
    sapgparam_failed       = 2
    build_directory_failed = 3
    no_authorization       = 4
    read_directory_failed  = 5
    too_many_read_errors   = 6
    empty_directory_list   = 7
    OTHERS                 = 8.

IF sy-subrc = 0.
  LOOP AT lt_files INTO lv_filename.
    WRITE: / lv_filename.
  ENDLOOP.
ENDIF.

12. File with Error Message

DATA: lv_file    TYPE string VALUE '/nonexistent/path/file.txt',
      lv_message TYPE string.

OPEN DATASET lv_file FOR INPUT IN TEXT MODE
  ENCODING UTF-8
  MESSAGE lv_message.

IF sy-subrc <> 0.
  WRITE: / 'Error opening:'.
  WRITE: / lv_message.
  WRITE: / 'Return Code:', sy-subrc.
ENDIF.

13. Line Break Modes

" Unix line break (LF)
OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE
  ENCODING UTF-8
  WITH UNIX LINEFEED.

" Windows line break (CRLF)
OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE
  ENCODING UTF-8
  WITH WINDOWS LINEFEED.

" Automatic (depending on server)
OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE
  ENCODING UTF-8
  WITH NATIVE LINEFEED.

" Smart: Write like Native, Read detects automatically
OPEN DATASET lv_file FOR INPUT IN TEXT MODE
  ENCODING UTF-8
  WITH SMART LINEFEED.

14. Positioning in File

DATA: lv_file TYPE string VALUE '/tmp/data.bin',
      lv_data TYPE x LENGTH 100,
      lv_pos  TYPE i.

OPEN DATASET lv_file FOR UPDATE IN BINARY MODE.

IF sy-subrc = 0.
  " Get position
  GET DATASET lv_file POSITION lv_pos.
  WRITE: / 'Current position:', lv_pos.

  " Jump to position
  SET DATASET lv_file POSITION 100.

  " Read from position 100
  READ DATASET lv_file INTO lv_data.

  CLOSE DATASET lv_file.
ENDIF.

15. Process Large Files Efficiently

CONSTANTS: c_buffer_size TYPE i VALUE 8192.

DATA: lv_file   TYPE string VALUE '/tmp/large_file.txt',
      lv_buffer TYPE string,
      lv_count  TYPE i.

OPEN DATASET lv_file FOR INPUT IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  DO.
    READ DATASET lv_file INTO lv_buffer.
    IF sy-subrc <> 0.
      EXIT.
    ENDIF.

    lv_count = lv_count + 1.

    " Process without storing all lines
    " process_line( lv_buffer ).

    " Show progress (every 10000 lines)
    IF lv_count MOD 10000 = 0.
      WRITE: / 'Processed:', lv_count, 'lines'.
    ENDIF.
  ENDDO.

  CLOSE DATASET lv_file.
  WRITE: / 'Total:', lv_count, 'lines'.
ENDIF.

16. Create Temporary File

DATA: lv_temp_file TYPE string,
      lv_guid      TYPE sysuuid_c32.

" Generate unique filename
lv_guid = cl_system_uuid=>create_uuid_c32_static( ).
lv_temp_file = |/tmp/temp_{ lv_guid }.txt|.

" Use temporary file
OPEN DATASET lv_temp_file FOR OUTPUT IN TEXT MODE ENCODING UTF-8.
TRANSFER 'Temporary data' TO lv_temp_file.
CLOSE DATASET lv_temp_file.

" ... processing ...

" Clean up
DELETE DATASET lv_temp_file.

Encoding Options

Encoding	Description
`DEFAULT`	System default
`UTF-8`	Unicode (recommended)
`NON-UNICODE`	Legacy, non-Unicode

sy-subrc Values

Value	Meaning
0	Successful
4	End of file (READ)
8	Error (file not found, no authorization)

ABAP Cloud Alternative

" In ABAP Cloud: FILE interface not available
" Instead: CL_ABAP_FILE_UTILITIES or XCO

" Example with XCO (Cloud)
DATA(lo_file) = xco_cp=>file( '/tmp/test.txt' ).

" Check if exists
IF lo_file->exists( ).
  " Read
  DATA(lv_content) = lo_file->read( )->as_string( ).
ENDIF.

Important Notes / Best Practice

Always call CLOSE DATASET – even on errors (TRY-FINALLY).
Use UTF-8 as encoding for modern files.
Use MESSAGE addition for meaningful error messages.
sy-subrc = 4 on READ means end of file (EOF).
APPENDING to append to existing files.
Process large files line by line instead of loading completely.
Check authorizations (S_DATASET) for file access.
Always specify absolute paths (not relative).
In ABAP Cloud, file operations are restricted – use XCO.
Binary files for non-text content (images, PDFs).