@@ -377,27 +377,31 @@ of your commands to change their appearance::
377
377
Writing to the error output
378
378
---------------------------
379
379
380
- If you rely on the output of a command (e.g. by redirecting it to a file for later reuse),
381
- you may want to get only the relevant information outputted by the command, excluding progress
382
- bars, notes, warnings and other error messages which have, most of the time, no value for reuse .
380
+ If you reuse the output of a command as the input of other commands or dump it
381
+ into a file for later reuse, you probably want to exclude progress bars, notes
382
+ and other output that provides no real value .
383
383
384
- For excluding irrelevant messages from the output, you need to make your command write them to the error
385
- output. Fortunately, the :class: `Symfony\\ Component\\ Console\\ Style\\ SymfonyStyle ` provides a convenient
386
- method to easily switch between both outputs:
387
- :method: `Symfony\\ Component\\ Console\\ Style\\ SymfonyStyle::getErrorStyle `.
388
- This method returns a new ``SymfonyStyle `` instance which makes use of the error output:
384
+ Commands can output information in two different streams: ``stdout `` (standard
385
+ output) is the stream where the real contents should be output and ``stderr ``
386
+ (standard error) is the stream where the errors and the debugging messages
387
+ should be output.
388
+
389
+ The :class: `Symfony\\ Component\\ Console\\ Style\\ SymfonyStyle ` class provides a
390
+ convenient method called :method: `Symfony\\ Component\\ Console\\ Style\\ SymfonyStyle::getErrorStyle `
391
+ to switch between both streams. This method returns a new ``SymfonyStyle ``
392
+ instance which makes use of the error output::
389
393
390
394
$io = new SymfonyStyle($input, $output);
391
395
392
- // Write to the output
396
+ // Write to the standard output
393
397
$io->write('Reusable information');
394
398
395
399
// Write to the error output
396
- $io->getErrorStyle()->warning('Irrelevant warning ');
400
+ $io->getErrorStyle()->warning('Debugging information or errors ');
397
401
398
402
.. note ::
399
403
400
- If you created the original ``SymfonyStyle `` instance with an ``OutputInterface `` object that is
401
- not an instance of :class: `Symfony\\ Component\\ Console\\ Output\\ ConsoleOutputInterface `, using
402
- ``getErrorStyle() `` will return an instance which makes use of the normal output instead of
403
- the error one, as if you did not called the method .
404
+ If you create a ``SymfonyStyle `` instance with an ``OutputInterface `` object
405
+ that is not an instance of :class: `Symfony\\ Component\\ Console\\ Output\\ ConsoleOutputInterface `,
406
+ the ``getErrorStyle() `` method will have no effect and the returned object
407
+ will still output to the standard output instead of the error output .
0 commit comments