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6.9 File Handles

A file handle is a reference to a data file, system file, or portable file. Most often, a file handle is specified as the name of a file as a string, that is, enclosed within ‘'’ or ‘"’.

A file name string that begins or ends with ‘|’ is treated as the name of a command to pipe data to or from. You can use this feature to read data over the network using a program such as ‘curl’ (e.g. GET '|curl -s -S http://example.com/mydata.sav'), to read compressed data from a file using a program such as ‘zcat’ (e.g. GET '|zcat mydata.sav.gz'), and for many other purposes.

pspp also supports declaring named file handles with the FILE HANDLE command. This command associates an identifier of your choice (the file handle's name) with a file. Later, the file handle name can be substituted for the name of the file. When pspp syntax accesses a file multiple times, declaring a named file handle simplifies updating the syntax later to use a different file. Use of FILE HANDLE is also required to read data files in binary formats. See FILE HANDLE, for more information.

In some circumstances, pspp must distinguish whether a file handle refers to a system file or a portable file. When this is necessary to read a file, e.g. as an input file for GET or MATCH FILES, pspp uses the file's contents to decide. In the context of writing a file, e.g. as an output file for SAVE or AGGREGATE, pspp decides based on the file's name: if it ends in ‘.por’ (with any capitalization), then pspp writes a portable file; otherwise, pspp writes a system file.

INLINE is reserved as a file handle name. It refers to the “data file” embedded into the syntax file between BEGIN DATA and END DATA. See BEGIN DATA, for more information.

The file to which a file handle refers may be reassigned on a later FILE HANDLE command if it is first closed using CLOSE FILE HANDLE. See CLOSE FILE HANDLE, for more information.