P

PATH

A colon-separated list of directories that are searched when the shell looks for commands and .'d files. An empty string resulting from a leading or trailing colon, or two adjacent colons is treated as a ., the current directory.

For more information, see ksh in the Utilities Reference.

PATH_MAX

The maximum permitted length of a pathname.

POSIX_STRICT

If this environment variable is set, some utilities (e.g., cp, ls, and more) interpret options according to POSIX specifications.

POSIXLY_CORRECT

This environment variable is used by Unix-style operating systems to alter behavior to comply with POSIX where it's different from the OS's default behavior. POSIXLY_CORRECT is a de facto standard that isn't defined by POSIX.

Here are some of its effects:

If the POSIXLY_CORRECT environment variable is set, functions that check the length of a pathname do so before removing any redundant . and .. components. If POSIXLY_CORRECT isn't set, the functions check the length after removing any redundant components.
If the POSIXLY_CORRECT environment variable is set, the posix option to be enabled for ksh. For more information, see "POSIX mode" in the documentation for ksh.

PRINTER

The name of the default printer, used by lpr.

PROCESSOR

Specifies the target CPU when building an image filesystem. If not set, the default is the same as the CPU of the host system (e.g., x86). For more information, see mkifs in the Utilities Reference.

PYTHONCASEOK

Ignore case in Python import statements (Windows).

PYTHONDEBUG

Display debugging output from the python parser.

PYTHONHOME

An alternate prefix directory (or prefix:exec_prefix) for Python. The default module search path uses prefix/pythonX.X.

PYTHONINSPECT

Inspect interactively after running the Python script, and force prompts, even if stdin doesn't appear to be a terminal.

PYTHONOPTIMIZE

Optimize the generated Python byte code.

PYTHONPATH

A colon-separated list of directories prefixed to the default module search path for Python. The result is stored in sys.path.

PYTHONSTARTUP

The file to execute on interactive startup of Python (no default).

PYTHONUNBUFFERED

Use unbuffered binary for stdout and stderr. See the Python documentation for details on internal buffering.

PYTHONVERBOSE

Make Python be verbose (trace import statements).