Purpose, Argument, Streams, Usage, Examples, Related

            ┌─FIRST─┐  ┌─1───────┐
>>──DROP──┬─┼───────┼──┼─────────┼──┬───────┬─┬──────────────────────────────────────>< 
          │ └─LAST──┘  └─numrecs─┘  ├─BYTES─┤ │
          │                         └─CHARS─┘ │
          └─┬─ALL─┬───────────────────────────┘
            └─*───┘

Use the DROP stage to discard one or more records at the beginning or end of its primary input stream. DROP selects the remaining records, copying them to its primary output stream. If its secondary output stream is connected, DROP passes any unselected records to its secondary output stream.

• FIRST
  discards records from the beginning of the input stream. This is the default.
  
  
• LAST
  discards records from the end of the input stream.
  
  
• ALL
  specifies that no input records are to be written to the primary output stream; all the records are to be written to the secondary output stream, if it is connected, otherwise DROP discards the records and the stage ends.
  
  
• numrecs
  is an unsigned integer which specifies the number of records to discard from the input stream. The default is 1. If you specify 0 for numrecs, DROP copies all of its input records to its primary output stream.
  
  
• BYTES
  CHARS
  specifies that the number of bytes is counted, rather than records. In general, the specified number of bytes will be taken in the middle of a record, which is then split after the last byte. When FIRST is specified; the first part of the split record is discarded and the remainder is selected. When LAST is specified, the first part of the split record is selected and the second part is discarded.

1. DROP FIRST does not delay the records. DROP LAST delays numrecs records.
   
   
2. DROP LAST stores the specified number of records in a buffer. For each subsequent input record (if any), DROP LAST writes the record residing longest in the buffer to the primary output stream. Otherwise, it discards the record. The input record is then stored in the buffer, queued on a first-in, first-out basis. When end-of-file is reached on the primary input stream, DROP LAST writes numrecs records from the buffer to the secondary output stream, if it is connected, otherwise it discards the records.
   
   
3. If the DROP stage discovers that all of its output streams are not connected, the DROP stage ends.
   
   
4. DROP FIRST disconnects its secondary output stream before it writes the records to its primary output stream. DROP LAST disconnects its primary output stream before it writes the unselected records to its secondary output stream.
   
   
5. DROP verifies that its secondary input stream is not connected and then begins execution.

1. The following pipeline reads the file in.txt and displays on the console only record number 10.
   
   

   **** Top of file ****
   Address Rxpipe
   
   'pipe < in.txt',
       '| drop first 9',
       '| take 1',
       '| console'
   
   Exit 0
   **** End of file ****
   

STEM, VARIABLE