PHP - send command line output to dynamically named files - php

Question

I have an application which is built in CakePHP 3.
It uses Console Commands to execute several intensive processes in the background using cron.
The application consists of 5 individual commands:
src/Command/Stage1Command.php
src/Command/Stage2Command.php
src/Command/Stage3Command.php
src/Command/Stage4Command.php
src/Command/Stage5Command.php
These can be executed manually by running each one individually, e.g. to execute Stage1Command.php:
$ php bin/cake.php stage1
To make them run via Cron, I created a 6th command (src/Command/RunAllCommand.php) which goes through these in order.
// src/Command/RunAllCommand.php
class RunAllCommand extends Command
{
public function execute(Arguments $args, ConsoleIo $io)
{
$stage1 = new Step1Command();
$this->executeCommand($stage1);
// ...
$stage5 = new Stage5Command();
$this->executeCommand($stage5);
}
}
This works fine so I can now execute everything with 1 command, php bin/cake.php run_all, which will be added as a cron task to automate running the 5 processes.
The problem I'm having is that each of the 5 commands (Stage1Command ... Stage5Command) produces output which appears on standard output in the console.
I need to be able to write the output produced by each of the 5 commands individually into dynamically named files.
So I can't do something like this
$ php bin/cake.php run_all > output.log
Because
output.log would contain everything, i.e. the output from all 5 commands.
output.log isn't a dynamic filename, it has been entered manually on the command line (or as the output destination of the cron task).
I looked at Redirecting PHP output to a text file and tried the following.
Added ob_start(); to RunAllCommand.php:
namespace App\Command;
ob_start();
class RunAllCommand extends Command { ... }
After executing the first task (Stage1Command) capturing ob_get_clean() to a variable called $content:
$stage1 = new Step1Command();
$this->executeCommand($stage1);
$content = ob_get_clean();
When I var_dump($content); it comes out as an empty string:
string(0) ""
But the output is still produced on the command line when executing php bin/cake.php run_all (RunAllCommand.php).
My plan for the dynamic filename was to generate it with PHP inside RunAllCommand.php, e.g.
// $id is a dynamic ID generated from a database call.
// This $id is being generated inside a foreach() loop so is different on each iteration (hence the dynamic nature of the filename).
$id = 234343;
$filename_stage1 = 'logs/stage1_' . $id . '.txt'; // e.g. "logs/stage1_234343.txt"
Then write $content to the above file, e.g.
file_put_contents($filename_stage1, $content);
So I have 2 problems:
The output is being echoed to the console, and unavailable in $content.
Assuming (1) is fixed, how to "reset" the output buffering such that I can use file_put_contents with 5 different filenames to capture the output for the relevant stage.

Answer 1

On each command file you could use the LogTrait then output what file is outputting before any commands to seperate what command is logging or setup the log config with different scopes to output to different files. example of outputting to the cli-debug.log file.
use Cake\Log\LogTrait;
class Stage1Command extends Command
{
use LogTrait;
public function execute(Arguments $args, ConsoleIo $io)
{
$this->log('Stage 1 Output: ', 'debug');
//do stuff
$this->log('output stage 1 stuff', 'debug');
}
}

Answer 2

I have two suggestions for solving your issue.
Option 1 - Using shell_exec
shell_exec returns a string of the output, so you can write it to a log file directly.
public function execute(Arguments $args, ConsoleIo $io)
{
$stage1_log = shell_exec('bin/cake stage1 arguments');
file_put_contents('stage1_dynamic_log_file.txt', $stage1_log);
$stage2_log = shell_exec('bin/cake stage2 arguments');
file_put_contents('stage2_dynamic_log_file.txt', $stage2_log);
}
Option 2 - Overwrite the ConsoleOut stream
Alternatively a more CakePHP style would be to call the command slightly differently. If you look at the contents of executeCommand() it does a few checks and then calls command->run($args, $io)
Also if you look at how the ConsoleIo is constructed, we can override the output method so instead of using php://stdout we could use a file instead, if you look at the code for ConsoleOutput it's just using normal fopen and fwrite.
use Cake\Console\ConsoleIo;
use Cake\Console\ConsoleOutput;
public function execute(Arguments $args, ConsoleIo $io)
{
// File names
$id = 234343;
$filename_stage1 = 'logs/stage1_' . $id . '.txt';
// Create command object
$stage1 = new Stage1Command();
// Define output as this filename
$output = new ConsoleOutput($filename_stage1);
// Create a new ConsoleIo using this new output method
$stage1_io = new ConsoleIo($output);
// Execute passing in the ConsoleIo with text file for output
$this->executeCommand($stage1, ['arguments'], $stage1_io);
}