Styjun

i installed python 3.7.2 still pip was not installed,for pip there must be pip.exe in folder script in directory where python is installed but in my device there nothing in it.

later i tried to install it by running get-pip.py but it throws an exception in command prompt

Command prompt throws exception :-

Installing collected packages: pip, setuptools, wheel Exception: Traceback (most recent call last):
File "C:UsersDel$inAppDataLocalProgramsPythonPython37libdistutilsuti l.py", line 187, in subst_vars return re.sub(r'$([a-zA-Z_][a-zA-Z_0-9]*)', _subst, s)
File "C:UsersDel$inAppDataLocalProgramsPythonPython37libre.py", line 192, in sub return _compile(pattern, flags).sub(repl, string, count) 
File "C:UsersDel$inAppDataLocalProgramsPythonPython37libdistutilsuti l.py", line 184, in _subst return os.environ[var_name]
File "C:UsersDel$inAppDataLocalProgramsPythonPython37libos.py", line 678, in getitem raise KeyError(key) from None KeyError: 'in'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:UsersDel$inAppDataLocalTemptmpwzho1r2wpip.zippip_internalcli base_command.py", line 179, in main status = self.run(options, args)
File "C:UsersDel$inAppDataLocalTemptmpwzho1r2wpip.zippip_internalcom mandsinstall.py", line 393, in run use_user_site=options.use_user_site, 
File "C:UsersDel$inAppDataLocalTemptmpwzho1r2wpip.zippip_internalreq __init__.py", line 57, in install_given_reqs **kwargs
File "C:UsersDel$inAppDataLocalTemptmpwzho1r2wpip.zippip_internalreq req_install.py", line 913, in install use_user_site=use_user_site, pycompile=pycompile,
File "C:UsersDel$inAppDataLocalTemptmpwzho1r2wpip.zippip_internalreq req_install.py", line 445, in move_wheel_files warn_script_location=warn_script_location,
File "C:UsersDel$inAppDataLocalTemptmpwzho1r2wpip.zippip_internalwhe el.py", line 320, in move_wheel_files prefix=prefix,
File "C:UsersDel$inAppDataLocalTemptmpwzho1r2wpip.zippip_internalloc ations.py", line 180, in distutils_scheme i.finalize_options()
File "C:UsersDel$inAppDataLocalProgramsPythonPython37libdistutilscom mandinstall.py", line 307, in finalize_options self.expand_basedirs()
File "C:UsersDel$inAppDataLocalProgramsPythonPython37libdistutilscom mandinstall.py", line 475, in expand_basedirs self._expand_attrs(['install_base', 'install_platbase', 'root'])
File "C:UsersDel$inAppDataLocalProgramsPythonPython37libdistutilscom mandinstall.py", line 469, in _expand_attrs val = subst_vars(val, self.config_vars)
File "C:UsersDel$inAppDataLocalProgramsPythonPython37libdistutilsuti l.py", line 189, in subst_vars raise ValueError("invalid variable '$%s'" % var) ValueError: invalid variable '$'in''

I'm certain that your username is the reason for this error. Python is trying to create a string of your username but the $ is causing issues. You can see this in the line ValueError: invalid variable '$'in''. Although there are other solutions, changing your username to DelSin will prevent many other headaches too.

From the code in distutils/utils.py:

def subst_vars (s, local_vars):
 """Perform shell/Perl-style variable substitution on 'string'. Every
 occurrence of '$' followed by a name is considered a variable, and
 variable is substituted by the value found in the 'local_vars'
 dictionary, or in 'os.environ' if it's not in 'local_vars'.
 'os.environ' is first checked/augmented to guarantee that it contains
 certain values: see 'check_environ()'. Raise ValueError for any
 variables not found in either 'local_vars' or 'os.environ'.
 """

This is utilizing the utility that's quite common in bash/Perl scripting, where you can substitute in a value using $:

SOMEPATH='$HOME/somefolder'

echo($SOMEPATH)
# '/path/to/somefolder'

Your username, unfortunately, mimics this and will cause problems until it is changed