12.2.9 Conditional Statements

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Radtest provides two kinds of conditional statements: if and case.

If statement

An if statement in its simplest form is:

if cond stmt

where cond is a conditional expression and stmt is a valid radtest statement. Optional newline may be inserted between cond stmt.

In this form, if evaluates the condition and if it yields true, executes the statement. For example:

if $REPLY[NAS-IP-Address] = 127.0.0.1
 print "Request from localhost"

More complex form of this statement allows to select between the two statements:

if cond stmt-1 else stmt-2 

Here, stmt-1 will be executed if cond evaluates to true, and stmt-2 will be executed if cond evaluates to false.

Notice, that an optional newline is allowed between cond and stmt-1 and right after else keyword. However, a newline before else constitutes an error.

If several statements should be executed in a branch of the if statement, use compound statement as in the example below:

if $REPLY_CODE != Accounting-Response
begin
 print "Accounting failed.\n"
 exit 1 
end else
 print "Accounting succeeded.\n"

If statements can be nested to any depth.

Case statement

Case statement allows select a statement based on whether a string expression matches given regular expression. The syntax of case statement is:

case expr in
expr-1 ) stmt-1
expr-2 ) stmt-2
…
expr-n ) stmt-n
end

where expr is a control expression, expr-1, expr-2 etc. are expressions evaluating to extended POSIX regular expressions (for the detailed description of these see (regex)Top section `Regular Expression Library' in Regular Expression Library).

Case statement first evaluates expr and converts it to string data type. Then it evaluates each expr-n in turn and tests if the resulting regular expression matches expr. If so, the statement stmt-n is executed and the execution of case statement finishes.

The following example illustrates the concept:

case $COMMAND in
"auth.*") authenticate($LIST, no)
"acct") authenticate($LIST, yes)
".*") begin
 print "Unknown command."
 exit 1
 end
end

Bourne shell programmers should notice that:

• Case statement ends with end, not esac.
• There is no need to put ;; at the end of each branch,
• Boolean operations are not allowed in expr-n.

This document was generated by Sergey Poznyakoff on December, 6 2008 using texi2html 1.78.