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Flujos de entrada/salida

CLI SAPI define algunas constantes para flujos de E/S que simplifican la programación en línea de comandos.

Constantes específicas de CLI
Constante Descripción
STDIN

Flujo abierto a stdin. Ahorra tener que abrirlo con

<?php
$stdin 
fopen('php://stdin''r');
?>
Si se desea leer una sola línea de stdin, puede usarse
<?php
$line 
trim(fgets(STDIN)); // lee una línea de STDIN
fscanf(STDIN"%d\n"$number); // lee un número de STDIN
?>

STDOUT

Flujo abierto a stdout. Ahorra tener que abrirlo con

<?php
$stdout 
fopen('php://stdout''w');
?>

STDERR

Flujo abierto a stderr. Ahora tener que abrirlo con

<?php
$stderr 
fopen('php://stderr''w');
?>

Teniendo esto en cuenta, no es necesario abrir por ejemplo un flujo a stderr, sino que puede usarse la constante en lugar del recurso de tipo flujo:

php -r 'fwrite(STDERR, "stderr\n");'
No es necesario cerrar explícitamente estos flujos, ya que se cierra automáticamente por PHP al finalizar el script.

Nota:

Estas constantes no están disponibles si se leyera el script PHP a partir de stdin.

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User Contributed Notes 3 notes

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2
Aurelien Marchand
3 years ago
Please remember in multi-process applications (which are best suited under CLI), that I/O operations often will BLOCK signals from being processed.

For instance, if you have a parent waiting on fread(STDIN), it won't handle SIGCHLD, even if you defined a signal handler for it, until after the call to fread has returned.

Your solution in this case is to wait on stream_select() to find out whether reading will block. Waiting on stream_select(), critically, does NOT BLOCK signals from being processed.

Aurelien
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1
ecrist at secure-computing dot net
3 years ago
The following code shows how to test for input on STDIN.  In this case, we were looking for CSV data, so we use fgetcsv to read STDIN, if it creates an array, we assume CVS input on STDIN, if no array was created, we assume there's no input from STDIN, and look, later, to an argument with a CSV file name.

Note, without the stream_set_blocking() call, fgetcsv() hangs on STDIN, awaiting input from the user, which isn't useful as we're looking for a piped file. If it isn't here already, it isn't going to be.

<?php
stream_set_blocking
(STDIN, 0);
$csv_ar = fgetcsv(STDIN);
if (
is_array($csv_ar)){
  print
"CVS on STDIN\n";
} else {
  print
"Look to ARGV for CSV file name.\n";
}
?>
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-2
James Zhu
3 years ago
Example:

<?php
function ReadStdin($prompt, $valid_inputs, $default = '') {
    while(!isset(
$input) || (is_array($valid_inputs) && !in_array($input, $valid_inputs)) || ($valid_inputs == 'is_file' && !is_file($input))) {
        echo
$prompt;
       
$input = strtolower(trim(fgets(STDIN)));
        if(empty(
$input) && !empty($default)) {
           
$input = $default;
        }
    }
    return
$input;
}

// you can input <Enter> or 1, 2, 3
$choice = ReadStdin('Please choose your answer or press Enter to continue: ', array('', '1', '2', '3'));

// check input is valid file name, use /var/path for input nothing
$file = ReadStdin('Please input the file name(/var/path):', 'is_file', '/var/path');
?>

you can add more functions if you want.
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