Input files to the awk program from any of the following sources
shall be text files:
* Any file operands or their equivalents, achieved by modifying
the awk variables ARGV and ARGC
* Standard input in the absence of any file operands
* Arguments to the getline function
Whether the variable RS is set to a value other than a <newline>
or not, for these files, implementations shall support records
terminated with the specified separator up to {LINE_MAX} bytes
and may support longer records.
If -f progfile is specified, the application shall ensure that
the files named by each of the progfile option-arguments are text
files and their concatenation, in the same order as they appear
in the arguments, is an awk program.
