Re: magic/absurd bash interpreter/compiler ?

In comp.compilers Eric <eric@deptj.eu> wrote:


(snip, I wrote)
>> One problem with many unix shells is that redirection is done too early.
>> Specifically, before an if test is done.


> I am tempted to think that this is a conceptual misunderstanding, so an
> example would be useful.


From the man page for csh:


    "The single-command form of if does output redirection even if the
      expression is false and the command is not executed."


echo false > file
if( 1 > 2 ) echo true > file


The if statement will open (and truncate) file before
testing the condition. At least for csh, I didn't try others.


-- glen
[That's one of the many, many bugs in csh. In posix shells such as
sh and bash, they do what you'd expect:


if [ 1 \> 2 ]; then echo true > file; fi # doesn't create the file
if [ 1 \> 2 ]; then echo true; fi > file # does create it


-John]

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