not able to execute cat command and loadtxt. I hadsame issue in basic video 8(loading dat from file).
In [45]: %pylab
Using matplotlib backend: TkAgg
Populating the interactive namespace from numpy and matplotlib

In [46]: cat company-a-dat.txt
  File "<ipython-input-46-e95588f4945f>", line 1
    cat company-a-dat.txt
              ^
SyntaxError: invalid syntax


In [47]: cat company-a-data.txt
  File "<ipython-input-47-37dbbe0090a4>", line 1
    cat company-a-data.txt
              ^
SyntaxError: invalid syntax


In [48]: cat company-a-data.txt
  File "<ipython-input-48-37dbbe0090a4>", line 1
    cat company-a-data.txt
              ^
SyntaxError: invalid syntax


In [49]: cat company-a-data.txt
  File "<ipython-input-49-37dbbe0090a4>", line 1
    cat company-a-data.txt
              ^
SyntaxError: invalid syntax


In [50]: year,profit=loadtxt('company-a-dat.txt)
  File "<ipython-input-50-6c82ded6f088>", line 1
    year,profit=loadtxt('company-a-dat.txt)
                                           ^
SyntaxError: EOL while scanning string literal


In [51]: year,profit=loadtxt('company-a-dat.txt')
---------------------------------------------------------------------------
OSError                                   Traceback (most recent call last)
<ipython-input-51-9d4241c7c624> in <module>
----> 1 year,profit=loadtxt('company-a-dat.txt')

c:\users\admin\appdata\local\programs\python\python36\lib\site-packages\numpy\lib\npyio.py in loadtxt(fname, dtype, comments, delimiter, converters, skiprows, usecols, unpack, ndmin, encoding, max_rows)
    979             fname = os_fspath(fname)
    980         if _is_string_like(fname):
--> 981             fh = np.lib._datasource.open(fname, 'rt', encoding=encoding)
    982             fencoding = getattr(fh, 'encoding', 'latin1')
    983             fh = iter(fh)

c:\users\admin\appdata\local\programs\python\python36\lib\site-packages\numpy\lib\_datasource.py in open(path, mode, destpath, encoding, newline)
    267
    268     ds = DataSource(destpath)
--> 269     return ds.open(path, mode, encoding=encoding, newline=newline)
    270
    271

c:\users\admin\appdata\local\programs\python\python36\lib\site-packages\numpy\lib\_datasource.py in open(self, path, mode, encoding, newline)
    621                                       encoding=encoding, newline=newline)
    622         else:
--> 623             raise IOError("%s not found." % path)
    624
    625

OSError: company-a-dat.txt not found.

In [52]: year,profit=loadtxt('company-a-data.txt')
---------------------------------------------------------------------------
OSError                                   Traceback (most recent call last)
<ipython-input-52-b48e6119614d> in <module>
----> 1 year,profit=loadtxt('company-a-data.txt')

c:\users\admin\appdata\local\programs\python\python36\lib\site-packages\numpy\lib\npyio.py in loadtxt(fname, dtype, comments, delimiter, converters, skiprows, usecols, unpack, ndmin, encoding, max_rows)
    979             fname = os_fspath(fname)
    980         if _is_string_like(fname):
--> 981             fh = np.lib._datasource.open(fname, 'rt', encoding=encoding)
    982             fencoding = getattr(fh, 'encoding', 'latin1')
    983             fh = iter(fh)

c:\users\admin\appdata\local\programs\python\python36\lib\site-packages\numpy\lib\_datasource.py in open(path, mode, destpath, encoding, newline)
    267
    268     ds = DataSource(destpath)
--> 269     return ds.open(path, mode, encoding=encoding, newline=newline)
    270
    271

c:\users\admin\appdata\local\programs\python\python36\lib\site-packages\numpy\lib\_datasource.py in open(self, path, mode, encoding, newline)
    621                                       encoding=encoding, newline=newline)
    622         else:
--> 623             raise IOError("%s not found." % path)
    624
    625

OSError: company-a-data.txt not found.

In [53]: year,profit=loadtxt('company-a-data.txt',unpack=true)
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-53-de6020824536> in <module>
----> 1 year,profit=loadtxt('company-a-data.txt',unpack=true)

NameError: name 'true' is not defined

In [54]: year,profit=loadtxt('company-a-data.txt',unpack=True)
---------------------------------------------------------------------------
OSError                                   Traceback (most recent call last)
<ipython-input-54-070812f8b62f> in <module>
----> 1 year,profit=loadtxt('company-a-data.txt',unpack=True)

c:\users\admin\appdata\local\programs\python\python36\lib\site-packages\numpy\lib\npyio.py in loadtxt(fname, dtype, comments, delimiter, converters, skiprows, usecols, unpack, ndmin, encoding, max_rows)
    979             fname = os_fspath(fname)
    980         if _is_string_like(fname):
--> 981             fh = np.lib._datasource.open(fname, 'rt', encoding=encoding)
    982             fencoding = getattr(fh, 'encoding', 'latin1')
    983             fh = iter(fh)

c:\users\admin\appdata\local\programs\python\python36\lib\site-packages\numpy\lib\_datasource.py in open(path, mode, destpath, encoding, newline)
    267
    268     ds = DataSource(destpath)
--> 269     return ds.open(path, mode, encoding=encoding, newline=newline)
    270
    271

c:\users\admin\appdata\local\programs\python\python36\lib\site-packages\numpy\lib\_datasource.py in open(self, path, mode, encoding, newline)
    621                                       encoding=encoding, newline=newline)
    622         else:
--> 623             raise IOError("%s not found." % path)
    624
    625

OSError: company-a-data.txt not found.

In [55]: