V7/SVR3.1 (The GNU Awk User’s Guide)

A.1 Major Changes Between V7 and SVR3.1

The awk language evolved considerably between the release of Version 7 Unix (1978) and the new version that was first made generally available in System V Release 3.1 (1987). This section summarizes the changes, with cross-references to further details:

The requirement for ‘;’ to separate rules on a line (see section awk Statements Versus Lines)
User-defined functions and the return statement (see section User-Defined Functions)
The delete statement (see section The delete Statement)
The do-while statement (see section The do-while Statement)
The built-in functions atan2(), cos(), sin(), rand(), and srand() (see section Numeric Functions)
The built-in functions gsub(), sub(), and match() (see section String-Manipulation Functions)
The built-in functions close() and system() (see section Input/Output Functions)
The ARGC, ARGV, FNR, RLENGTH, RSTART, and SUBSEP predefined variables (see section Predefined Variables)
Assignable $0 (see section Changing the Contents of a Field)
The conditional expression using the ternary operator ‘?:’ (see section Conditional Expressions)
The expression ‘indx in array’ outside of for statements (see section Referring to an Array Element)
The exponentiation operator ‘^’ (see section Arithmetic Operators) and its assignment operator form ‘^=’ (see section Assignment Expressions)
C-compatible operator precedence, which breaks some old awk programs (see section Operator Precedence (How Operators Nest))
Regexps as the value of FS (see section Specifying How Fields Are Separated) and as the third argument to the split() function (see section String-Manipulation Functions), rather than using only the first character of FS
Dynamic regexps as operands of the ‘~’ and ‘!~’ operators (see section Using Dynamic Regexps)
The escape sequences ‘\b’, ‘\f’, and ‘\r’ (see section Escape Sequences)
Redirection of input for the getline function (see section Explicit Input with getline)
Multiple BEGIN and END rules (see section The BEGIN and END Special Patterns)
Multidimensional arrays (see section Multidimensional Arrays)