---
# System prepended metadata

title: PC987 Day 2 (20201215)

---

# PC987 Day 2 (20201215)

1. Make sure you have installed Python in your local machine (https://www.anaconda.com/products/individual)
2. Make sure you have your git installed. (https://gitforwindows.org/)
3. Configure your git id if you not already done so.
```bash
git config --global user.email "your email goes here"
git config --global user.name "your name goes here"
```
3. Git clone or fork the following repo "https://gitlab.com/goh.yongkheng/pc987.git"
    - fork will allow you to own a copy of your project, that means you can change it and push it back to your own git account
    - clone is just download a copy of the project

## Bash shell commands

1. listing of files and content: `cat`, `ls`, `head`
2. redirection: 
```bash=
$ ls scripts/* > filelist.log
```
3. piping:
```bash=
$ ls scripts/* | grep pdf$
```
4. aliasing commands
```bash
$ alias ll="ls -lh"
```
to add the alias permanantly to your shell, add the above line to the file `.bash_aliases` in your home directory.
5. Creating a bash script: open a file and adding the commands. For example, add the following line to `myscript.sh`.
```bash=
#!/usr/bin/bash
ls scripts/* | grep pdf$ | xargs -i cp {} backup/
```
6. Different state of a process in Linux
- running:  foreground (`fg`) or background (`bg`)
- suspend(`^z`): your process is waiting for instruction, ie not running
- use `jobs` to list the processes currently running/waiting
- to start a process in background directly
```bash=
$ python3 processor_temp.py > output.log &
```
- display current processes
```bash=
$ ps -f
$ ps -u dummy
$ ps -aux
```
- use nice number to control process priority
```bash=
$ renice 10 <process ID>
```
- to stop/kill a job
```bash=
$ kill -9 <process ID>
```


## Python virtual environment

- We setup virtual environment for
    - separate user python with os python
    - clean environment
    - capture the python dependencies of your project
- in case of venv is not install, do this:
```bash=
$ sudo apt install python3-venv
```
- to create a virtual env
```bash=
$ python3 -m venv <name of your virtual env>
$ source <name of your virtual env>/bin/activate
(env) $ deactivate   # to deactive the virtual env
```
- create dependency requirements
```bash=
$ source env/bin/activate
(env) $ pip install markdown
(env) $ pip freeze > requirements.txt
```
in the new virtual env or new server
```bash=
(another env) $ pip install -r requirements.txt
```