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Full Discussion: ksh bug?
Top Forums UNIX for Advanced & Expert Users ksh bug? Post 302875875 by Don Cragun on Wednesday 20th of November 2013 03:49:10 PM
Old 11-20-2013
Quote:
Originally Posted by MadeInGermany
I think I discovered a bug in ksh.
Code:
$ cat test.sh
x=`echo hello | cat 2>&1 >/dev/null`
echo $x
y=`echo hello | cat >/dev/null 2>&1`
echo $y

works with all shells, including ksh in normal mode.
But does not work with ksh -x:
Code:
$ ksh -x test.sh
+ + echo hello
+ cat
+ 2>& 1 x=1> /dev/null
+ echo 1> /dev/null
1> /dev/null
+ + echo hello
+ cat
+ 1> /dev/null 2>& 1
y=
+ echo

sh -x or bash -x or zsh -x do it correctly:
Code:
$ bash -x test.sh
++ echo hello
++ cat
+ x=
+ echo

++ echo hello
++ cat
+ y=
+ echo

I guess I don't see what's wrong.

It looks like ksh is running the parts of the pipelines in different threads (so you see jumbled output in the trace), but both x and y are assigned empty values and the echo $x and echo $y seem to have done the right thing. What am I missing?

If you mean that the trace output from bash and zsh don't show redirection operations performed by the shell, I don't think that is a ksh bug.

Last edited by Don Cragun; 11-20-2013 at 04:53 PM.. Reason: Add final comment on redirections.
 

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DEFINE(3)								 1								 DEFINE(3)

define - Defines a named constant

SYNOPSIS
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)
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