PHP's error_log() vs syslog()

Question

I'm trying to decide what functionality to use for logging to a custom file.

Background
We have several PHP processes, both running as Apaches (mod_php) and as Deamons (CLI, forked). I would like to be able to specify a log file per process/task to write to. For both the Apache processes as the Deamons, multiple processes will be writing to the same file.

Options
PHP offers both error_log() and syslog() . Both seem to offer more or less the same functionality.

My question

• What are the pros and cons of those functions?
• Which one to choose? ( and why? )
• What if I drop the requirement of multiple files?

Answer 1

syslog sends the message to the OS logger, while error_log has multiple options, either to the OS logger, to an email, to a file, or to the SAPI logging handler, as is stated in the documentation.

Since you say yo want to write on multiple logs, I'd recommend error_log with $message_type = 3 , wich lets you add messages to the file set in the $destination parameter.