Three problems or characteristics of Unix-related methods and class

I now know the cause of the Problem 1. Under macOS 12.6.5, there is no python file and pip in the system path, but pyhon3 and pip3.

The following code

"which python3".unixCmd

returns:

/usr/bin/python3

and the following code

"which pip3".unixCmd

returns:

-> 1507
/usr/bin/pip3

So the followings work if one uses only the system default python3:

"pip3 install pyphen".unixCmd

The code above returns:

-> 1511
Defaulting to user installation because normal site-packages is not writeable
Collecting pyphen
  Downloading pyphen-0.14.0-py3-none-any.whl (2.0 MB)
Installing collected packages: pyphen
Successfully installed pyphen-0.14.0

The following code

"pip3 install pyphen".systemCmd

and the following code

(
var p, l;
p = Pipe.new("pip3 install pyphen", "r");
l = p.getLine;
while({l.notNil}, {l.postln; l = p.getLine; });
p.close;
)

returns:

Defaulting to user installation because normal site-packages is not writeable
Requirement already satisfied: pyphen in /Users/prko/Library/Python/3.9/lib/python/site-packages (0.14.0)
-> 0
"pip3 install pyphen".unixCmdGetStdOut

The code above returns:

-> Defaulting to user installation because normal site-packages is not writeable
Requirement already satisfied: pyphen in /Users/prko/Library/Python/3.9/lib/python/site-packages (0.14.0)
"pip3 install pyphen".unixCmdGetStdOutLines

The code above returns:

> [ Defaulting to user installation because normal site-packages is not writeable, Requirement already satisfied: pyphen in /Users/prko/Library/Python/3.9/lib/python/site-packages (0.14.0) ]

And the following code

"pip3 install pyphen".runInTerminal

runs a terminal window, and the result is as follows:

Last login: Wed May 17 12:19:39 on ttys001
/Users/prko/Library/Application\ Support/SuperCollider/tmp/SCStringForTerminal1571796326.command ; exit;
prko@PyoungRyangs-Virtual-Machine ~ % /Users/prko/Library/Application\ Support/SuperCollider/tmp/SCStringForTerminal1571796326.command ; exit;
Defaulting to user installation because normal site-packages is not writeable
Requirement already satisfied: pyphen in ./Library/Python/3.9/lib/python/site-packages (0.14.0)

Saving session...
...copying shared history...
...saving history...truncating history files...
...completed.

[Process completed]

I think Problem 1 has been solved.