How to Redirect Stdout to a File in PHP

How to redirect echo command output to a text file in PHP

Just use fopen/fwrite to write to a file (this will create the output.txt if it does not exist, else overwrites it)

$myfile = fopen("output.txt", "w") or die("Unable to open file!");
fwrite($myfile, $TOKEN);
fclose($myfile);

How can I redirect the output of a exec call in php ( and its stderr) to the calling program?

PHP's exec() is quite unlike the exec() of any other language.

When invoked as just exec("some string"), it gets some string interpreted as shell code by a shell in a child process, and returns the last line of its output stripped of all the trailing ASCII whitespace characters.

Here, you're not doing anything with that output though.

Now as to that:

/usr/bin/php -f t.php 2 2&>1

shell code, note that the behaviour varies between sh implementations.

In POSIX compliant sh implementations, that's meant to be the same as:

/usr/bin/php -f t.php 2 2 &
>1

That is run that php command in background, and then open the file called 1 for writing, but without any command whose output to send there.

Not all sh implementations are compliant there are some shells implement a non-standard &> redirection operator.

In the GNU implementation of sh (bash), that's interpreted as:

/bin/bin/php -f t.php 2 2 &> "1"

Which is running that php command (with 2 "2" arguments) with both stdout and stderr redirected to the file called 1. So it will produce no output on stdout (captured by php) but send /usr/bin/php's output to that file.

In zsh, the 2&> "1" redirects both fd 2 and fd 2 to the file called 1, as if you had written 2> "1" 2>&2. With fd 2 redirected twice, zsh normally implements a tee-like behaviour where the data is sent to both locations (here the same), but when invoked as sh (not that many systems have sh implemented with zsh), zsh disables that tee-like feature, so the 2&>1 ends up being the same as 2> "1", so redirects stderr to the file called 1. In any case, since that php command doesn't output anything on stderr, it makes no difference.

mksh (MirBSD sh) behaves like zsh-as-sh above.

Here, you could do

echo exec('/usr/bin/php -f t.php') . "\n";

To print the contents of the last line of the output of that php command followed by a newline character. Or (maybe what you intended?):

echo exec('/usr/bin/php -f t.php 2>&1') . "\n";

For the last line of the output+errors of that php command.

But here, it sounds like you just want to leave the output of that php command untouched; not capture it, but let it go to the same destination as the echo does.

PHP has some system() and passthru() functions, but those capture the output of the shell command to display it afterwards.

You can however use the pcntl_exec() function which is more like the exec() of other languages, except that it doesn't let you set argv[0].

pcntl_exec("/usr/bin/php", ["-f", "t.php", "2"]);

Like the exec() of other languages, it runs it in the same process, so it's the last thing the php script will do. And it doesn't invoke a shell, just runs the command directly.

That's probably not what you'll want to use in a web application though. In a web application, php needs to know what output it's going to send before it sends it, if only to fill in Content-Length type of HTTP header. There, you'd use passthru() or system() or shell_exec()...

See also:

• shell_exec()
• passthru()
• system()
• proc_open()
• popen()

How to redirect output of PHP script DURING execution?

If you want to capture parser errors, you need to:

1. Make sure display_errors is On

2. Set an error_prepend_string and an error_append_string

3. Call ob_start from an auto_prepend file that runs before every PHP file you might be executing.

4. Use set_error_handler as you normally would, and make your callback sift through the named output buffer, looking for your custom error_prepend_string and error_append_string. If you find it, then shunt your output wherever you want it. If you don't, then let it go wherever it would normally.

Most of this can be achieved through ini_set calls, but the auto_prepend file will need to be specified in your php.ini.

How to view or redirect php.exe's stdout to a file?

PHP usually writes to the Apache logs... did you check there?

If it isn't writing there, see what log mechanism PHP's source uses and copy that because PHP writes to apache logs :)

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