MPE/iX Shell and Utilities Reference Manual, Vol 1

awk(1) MPE/iX Shell and Utilities awk(1)

A function deﬁnition can appear in the place of a pattern {action} rule. The parameter-list

contains any number of normal (scalar) and array variables separated by commas. When you

call a function, awk passes scalar arguments by value, and array arguments by reference. The

names speciﬁed in the parameter-list are local to the function; all other names used in the

function are global. You can deﬁne local variables by adding them to the end of the parameter

list as long as no call to the function uses these extra parameters.

A function returns to its caller either when it performs the ﬁnal statement in the function, or

when it reaches an explicit return statement. The return value, if any, is speciﬁed in the

return statement (see the Actions section).

Patterns

A pattern is a regular expression, a special pattern, a pattern range, or any arithmetic expres-

sion.

BEGIN is a special pattern used to label actions that awk performs before reading any input

records. END is a special pattern used to label actions that awk performs after reading all

input records.

You can give a pattern range as

pattern1,pattern2

This matches all lines from one that matches pattern1 to one that matches pattern2, inclusive.

If you omit a pattern, or if the numeric value of the pattern is non-zero (true), awk performs

the resulting action for the line.

Actions

An action is a series of statements terminated by semicolons, newlines, or closing braces. A

condition is any expression; awk considers a non-zero value true, and a zero value false. A

statement is one of the following or any series of statements enclosed in braces.

# expression statement, e.g. assignment

expression

# if statement

if (condition)

statement

[else

statement]

# while loop

while (condition)

statement

Commands and Utilities 1-29