Manual:$wgColorErrors

From MediaWiki.org

Debug/logging: $wgColorErrors
Whether to color command-line error messages.
Introduced in version:	1.6.0 (r13452)
Removed in version:	still in use
Allowed Values:	(boolean)
Default Value:	true

Other settings: Alphabetical | By Function

[edit] Details

If true, some error messages will be colorized when running scripts on the command line; this can aid picking important things out when debugging. Ignored when running on Windows or when output is redirected to a file.