It makes sense when you consider the effect that field splitting or pathname expansion could have. a=$1 could yield a=word1 word2 which would then execute an unintended command, word2, with a modification to its environment.
This bypassing of actions which can increase the number of tokens also occurs in the case statement: In case word in ..., word is not subject to field splitting and pathname expansion.
Quote:
Originally Posted by Corona688
Interesting disctinction. I've also noticed that IFS applies here:
But not here:
I have not been able to reproduce such behavior nor have I been able to find any documentation implying that such behavior is intentional. Perhaps there's a bug in your shell? Can you specify the shell and demonstrate how you trigger such behavior?
I tried the following on bash 3.1.17 and did not observe any command substitution syntax-dependent difference in field splitting:
Regards,
Alister
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Discussion started by: scriptor
8 Replies
LEARN ABOUT PHP
define
DEFINE(3) 1 DEFINE(3)define - Defines a named constantSYNOPSIS
bool define (string $name, mixed $value, [bool $case_insensitive = false])
DESCRIPTION
Defines a named constant at runtime.
PARAMETERS
o $name
- The name of the constant.
o $value
- The value of the constant; only scalar and null values are allowed. As of PHP 7 it also possible to use array value. Scalar val-
ues are integer, float, string or boolean values. It is possible to define resource constants, however it is not recommended and
may cause unpredictable behavior.
o $case_insensitive
- If set to TRUE, the constant will be defined case-insensitive. The default behavior is case-sensitive; i.e. CONSTANT and Con-
stant represent different values.
Note
Case-insensitive constants are stored as lower-case.
RETURN VALUES
Returns TRUE on success or FALSE on failure.
CHANGELOG
+--------+---------------------------+
|Version | |
| | |
| | Description |
| | |
+--------+---------------------------+
| 7.0.0 | |
| | |
| | |
| | array values are allowed. |
| | |
+--------+---------------------------+
EXAMPLES
Example #1
Defining Constants
<?php
define("CONSTANT", "Hello world.");
echo CONSTANT; // outputs "Hello world."
echo Constant; // outputs "Constant" and issues a notice.
define("GREETING", "Hello you.", true);
echo GREETING; // outputs "Hello you."
echo Greeting; // outputs "Hello you."
// Works as of PHP 7
define('ANIMALS', array(
'dog',
'cat',
'bird'
));
echo ANIMALS[1]; // outputs "cat"
?>
SEE ALSO defined(3), constant(3), The section on Constants.
PHP Documentation Group DEFINE(3)