The actual colors to be used are configured using the environment variable
   PG_COLORS
   (note plural).  The value is a colon-separated list of
   key=value
The following keys are currently in use:
errorused to highlight the text “error” in error messages
warningused to highlight the text “warning” in warning messages
noteused to highlight the text “detail” and “hint” in such messages
locusused to highlight location information (e.g., program name and file name) in messages
   The default value is
   error=01;31:warning=01;35:note=01;36:locus=01
   (01;31 = bold red, 01;35 = bold
   magenta, 01;36 = bold cyan, 01 = bold
   default color).
  
This color specification format is also used by other software packages such as GCC, GNU coreutils, and GNU grep.