PY_3

Implementation of simple UNIX like shell using Python.

Main module is commands.py and for running the shell using the command

python commands.py

All commands are implemented as separated modules which are present in different files with the filename same as the name of the command.

SUPPORTED COMMANDS

• Directory related commands

  • ls: list directory contents
  • mkdir: make directories
  • pwd: return working directory name
  • rmdir: remove directories
  • cd: change current working directory

• FileDirectory related commands

  • cat: concatenate and print files
  • cp: copy files
  • rm: remove directory links
  • mv: move files
  • grep: file pattern searcher
  • head: display first lines of a file
  • tail: display the last part of a file
  • sizeof: size of file
  • find: walk a file hierarchy

• Built-in commands

  • date: display date or time
  • whoami: display effective user id
  • hostname: print hostname of current host system
  • timeit: measures execution time
  • exit: terminate the shell
  • history: previous commands

• Ctrl-C signal handling

Unittest

Unittest module is used for testing for the entire shell. The unittest unit testing framework was originally inspired by JUnit and has a similar flavor as major unit testing frameworks in other languages. test_file.py has test for the modules in it.

Example:

pragyas-mbp-2:PY_3 pragkuma$ python test_file.py
----------------------------------------------------------------------
Ran 22 tests in 0.112s
OK

Input/Output Format

Input from the 'stdin' in an infinite loop till an “exit” is entered. The corresponding output should be printed to 'stdout'.

Example:

pragyas-mbp-2:PY_3 pragkuma$ python commands.py 
MyShell> find . -name grep
./grep
MyShell> date -u
Mon Aug 5 09:14:11 UTC 2019
MyShell> whoami
pragkuma
MyShell> sizeof hostname.py
2278 bytes
MyShell> exit
exiting prompt

Help/Usage of command

Write the name of the command followed by --help in order to get the usage of the command.

Example:

MyShell> find --help
usage: 
NAME
     find -- walk a file hierarchy
DESCRIPTION
    The find utility recursively descends the directory tree for each path listed,
    evaluating an expression (composed of the ``primaries'' and ``operands'' listed below)
    in terms of each file in the tree.

       [-h] [-name NAME] [args [args ...]]

positional arguments:
  args                  enter the filenames

optional arguments:
  -h, --help            show this help message and exit
  -name NAME, --name NAME
                        expression determines what to find