A.4 Extensions in the Bell Laboratories awk

Brian Kernighan, one of the original designers of Unix awk, has made his version available via his home page (see section Other Freely Available awk Implementations). This section describes extensions in his version of awk that are not in POSIX awk.

• The `-mf N' and `-mr N' command-line options to set the maximum number of fields and the maximum record size, respectively (see section Command-Line Options). As a side note, his awk no longer needs these options; it continues to accept them to avoid breaking old programs.

• The fflush built-in function for flushing buffered output (see section Input/Output Functions).

• The `**' and `**=' operators (see section Arithmetic Operators and Assignment Expressions).

• The use of func as an abbreviation for function (see section Function Definition Syntax).

The Bell Laboratories awk also incorporates the following extensions, originally developed for gawk:

• The `\x' escape sequence (see section 3.2 Escape Sequences).

• The `/dev/stdin', `/dev/stdout', and `/dev/stderr' special files (see section Special File Names in gawk).

• The ability for FS and for the third argument to split to be null strings (see section Making Each Character a Separate Field).

• The nextfile statement (see section Using gawk's nextfile Statement).

• The ability to delete all of an array at once with `delete array' (see section The delete Statement).