8.8 FILE HANDLE

For text files:
        FILE HANDLE handle_name
                /NAME=’file_name
                [/MODE=CHARACTER]
                [/ENDS={CR,CRLF}]
                /TABWIDTH=tab_width
                [ENCODING=’encoding’]

For binary files in native encoding with fixed-length records:
        FILE HANDLE handle_name
                /NAME=’file_name’
                /MODE=IMAGE
                [/LRECL=rec_len]
                [ENCODING=’encoding’]

For binary files in native encoding with variable-length records:
        FILE HANDLE handle_name
                /NAME=’file_name’
                /MODE=BINARY
                [/LRECL=rec_len]
                [ENCODING=’encoding’]

For binary files encoded in EBCDIC:
        FILE HANDLE handle_name
                /NAME=’file_name’
                /MODE=360
                /RECFORM={FIXED,VARIABLE,SPANNED}
                [/LRECL=rec_len]
                [ENCODING=’encoding’]

Use FILE HANDLE to associate a file handle name with a file and its attributes, so that later commands can refer to the file by its handle name. Names of text files can be specified directly on commands that access files, so that FILE HANDLE is only needed when a file is not an ordinary file containing lines of text. However, FILE HANDLE may be used even for text files, and it may be easier to specify a file’s name once and later refer to it by an abstract handle.

Specify the file handle name as the identifier immediately following the FILE HANDLE command name. The identifier INLINE is reserved for representing data embedded in the syntax file (see BEGIN DATA) The file handle name must not already have been used in a previous invocation of FILE HANDLE, unless it has been closed by an intervening command (see CLOSE FILE HANDLE).

The effect and syntax of FILE HANDLE depends on the selected MODE:

• In CHARACTER mode, the default, the data file is read as a text file. Each text line is read as one record.

  In CHARACTER mode only, tabs are expanded to spaces by input programs, except by DATA LIST FREE with explicitly specified delimiters. Each tab is 4 characters wide by default, but TABWIDTH (a PSPP extension) may be used to specify an alternate width. Use a TABWIDTH of 0 to suppress tab expansion.

  A file written in CHARACTER mode by default uses the line ends of the system on which PSPP is running, that is, on Windows, the default is CR LF line ends, and on other systems the default is LF only. Specify ENDS as CR or CRLF to override the default. PSPP reads files using either convention on any kind of system, regardless of ENDS.

• In IMAGE mode, the data file is treated as a series of fixed-length binary records. LRECL should be used to specify the record length in bytes, with a default of 1024. On input, it is an error if an IMAGE file’s length is not an integer multiple of the record length. On output, each record is padded with spaces or truncated, if necessary, to make it exactly the correct length.
• In BINARY mode, the data file is treated as a series of variable-length binary records. LRECL may be specified, but its value is ignored. The data for each record is both preceded and followed by a 32-bit signed integer in little-endian byte order that specifies the length of the record. (This redundancy permits records in these files to be efficiently read in reverse order, although PSPP always reads them in forward order.) The length does not include either integer.
• Mode 360 reads and writes files in formats first used for tapes in the 1960s on IBM mainframe operating systems and still supported today by the modern successors of those operating systems. For more information, see OS/400 Tape and Diskette Device Programming, available on IBM’s website.

  Alphanumeric data in mode 360 files are encoded in EBCDIC. PSPP translates EBCDIC to or from the host’s native format as necessary on input or output, using an ASCII/EBCDIC translation that is one-to-one, so that a “round trip” from ASCII to EBCDIC back to ASCII, or vice versa, always yields exactly the original data.

  The RECFORM subcommand is required in mode 360. The precise file format depends on its setting:

  F

  FIXED

  This record format is equivalent to IMAGE mode, except for EBCDIC translation.

  IBM documentation calls this *F (fixed-length, deblocked) format.

  V

  VARIABLE

  The file comprises a sequence of zero or more variable-length blocks. Each block begins with a 4-byte block descriptor word (BDW). The first two bytes of the BDW are an unsigned integer in big-endian byte order that specifies the length of the block, including the BDW itself. The other two bytes of the BDW are ignored on input and written as zeros on output.

  Following the BDW, the remainder of each block is a sequence of one or more variable-length records, each of which in turn begins with a 4-byte record descriptor word (RDW) that has the same format as the BDW. Following the RDW, the remainder of each record is the record data.

  The maximum length of a record in VARIABLE mode is 65,527 bytes: 65,535 bytes (the maximum value of a 16-bit unsigned integer), minus 4 bytes for the BDW, minus 4 bytes for the RDW.

  In mode VARIABLE, LRECL specifies a maximum, not a fixed, record length, in bytes. The default is 8,192.

  IBM documentation calls this *VB (variable-length, blocked, unspanned) format.

  VS

  SPANNED

  The file format is like that of VARIABLE mode, except that logical records may be split among multiple physical records (called segments) or blocks. In SPANNED mode, the third byte of each RDW is called the segment control character (SCC). Odd SCC values cause the segment to be appended to a record buffer maintained in memory; even values also append the segment and then flush its contents to the input procedure. Canonically, SCC value 0 designates a record not spanned among multiple segments, and values 1 through 3 designate the first segment, the last segment, or an intermediate segment, respectively, within a multi-segment record. The record buffer is also flushed at end of file regardless of the final record’s SCC.

  The maximum length of a logical record in VARIABLE mode is limited only by memory available to PSPP. Segments are limited to 65,527 bytes, as in VARIABLE mode.

  This format is similar to what IBM documentation call *VS (variable-length, deblocked, spanned) format.

  In mode 360, fields of type A that extend beyond the end of a record read from disk are padded with spaces in the host’s native character set, which are then translated from EBCDIC to the native character set. Thus, when the host’s native character set is based on ASCII, these fields are effectively padded with character X'80'. This wart is implemented for compatibility.

The NAME subcommand specifies the name of the file associated with the handle. It is required in all modes but SCRATCH mode, in which its use is forbidden.

The ENCODING subcommand specifies the encoding of text in the file. For reading text files in CHARACTER mode, all of the forms described for ENCODING on the INSERT command are supported (see INSERT). For reading in other file-based modes, encoding autodetection is not supported; if the specified encoding requests autodetection then the default encoding is used. This is also true when a file handle is used for writing a file in any mode.