File: gawk.info,  Node: Testing field creation,  Next: Multiple Line,  Prev: Splitting By Content,  Up: Reading Files

4.8 Checking How 'gawk' Is Splitting Records
============================================

As we've seen, 'gawk' provides three independent methods to split input
records into fields.  The mechanism used is based on which of the three
variables--'FS', 'FIELDWIDTHS', or 'FPAT'--was last assigned to.  In
addition, an API input parser may choose to override the record parsing
mechanism; please refer to *note Input Parsers:: for further information
about this feature.

   To restore normal field splitting after using 'FIELDWIDTHS' and/or
'FPAT', simply assign a value to 'FS'.  You can use 'FS = FS' to do
this, without having to know the current value of 'FS'.

   In order to tell which kind of field splitting is in effect, use
'PROCINFO["FS"]' (*note Auto-set::).  The value is '"FS"' if regular
field splitting is being used, '"FIELDWIDTHS"' if fixed-width field
splitting is being used, or '"FPAT"' if content-based field splitting is
being used:

     if (PROCINFO["FS"] == "FS")
         REGULAR FIELD SPLITTING ...
     else if (PROCINFO["FS"] == "FIELDWIDTHS")
         FIXED-WIDTH FIELD SPLITTING ...
     else if (PROCINFO["FS"] == "FPAT")
         CONTENT-BASED FIELD SPLITTING ...
     else
         API INPUT PARSER FIELD SPLITTING ... (advanced feature)

   This information is useful when writing a function that needs to
temporarily change 'FS' or 'FIELDWIDTHS', read some records, and then
restore the original settings (*note Passwd Functions:: for an example
of such a function).