# Cygwin setup on *Windows*
[Cygwin](https://www.cygwin.com) is a Unix-Emulator that provides
a terminal in which Unix commands can be executed on Windows
using
[bash](https://en.wikipedia.org/wiki/Bash_(Unix_shell))
(*Bourne Again Shell*) as command-line interpreter -
*bash* was developed in 1989 as a successor to the
*Bourne Shell:*
*[sh](https://en.wikipedia.org/wiki/Bourne_shell)*.
[<bash terminal>](https://cdn.ttgtmedia.com/rms/onlineimages/REF_bash_command_line_3.jpg)
*Cygwin* is <span style="text-decoration:underline">not</span>
a Unix container or virtual machine system (unlike
[WSL](https://learn.microsoft.com/en-us/windows/wsl/about)).
*Cygwin* emulates most (not all) Unix system calls such that
most Unix commands can execute on Windows.
Alternatives to *Cygwin* such as
[GitBash]()
can be used, but have some flaws and drawbacks on Windows
(*GitBash*, for example, performs strange path conversions, see
[link](https://stackoverflow.com/questions/54258996/git-bash-string-parameter-with-at-start-is-being-expanded-to-a-file-path)).
Good introductions to *bash* are:
- [https://cs.lmu.edu/~ray/notes/bash](https://cs.lmu.edu/~ray/notes/bash).
- Also recommended is the
[Tutorial for Beginners](https://linuxconfig.org/bash-scripting-tutorial-for-beginners).
## Steps
1. [Installation](#1-installation)
2. [Configure paths in .bashrc](#2-configure-paths-in-bashrc)
## 1. Installation
1. Download the installer `setup-x86_64.exe` from
[https://www.cygwin.com/install.html](https://www.cygwin.com/install.html).
1. Run the installer `setup-x86_64.exe`.
- select useful Unix commands during installation:
- Editors/`vim` - visual editor,
- Web/`wget` - web downloader,
- Net/`curl` - web downloader.
1. Change *cygwin* default path `/cygdrive/c` to: `/c`:
- navigate to the *cygwin* installation directory.
- inside, edit `/etc/fstab` and replace line
```
none /cygdrive cygdrive binary,posix=0,user 0 0
with:
none / cygdrive binary,posix=0,user 0 0
```
1. Add bash-user that works with Windows and create
*bash* HOME directory.
- Find out your Windows user name: <user_name>
- Create or select a directory that you want to use as
HOME-directory for *bash*, e.g. your Windows
HOME-directory `C:\Users\<user_name>`.
- Edit file `/etc/nsswitch.conf`:
- to use Windows HOME-directory, comment line
```
#db_home:
```
- for using a new directory as HOME-directory, enter
```
db_home: /cygdrive/c/<path>
```
1. Open a new *bash* terminal and test changes:
```sh
$ whoami
<user_name> # your user name appears
$ echo $HOME # print path to HOME-directory
<home_directory> # output, e.g. /c/Users/svgr
$ cd $HOME # change into HOME-directory
$ ls -la # show content
total 203
drwxr-xr-x+ 1 svgr2 Kein 0 Oct 4 22:20 .
drwxrwx---+ 1 svgr2 Kein 0 Jan 1 2022 ..
-rw------- 1 svgr2 Kein 14476 Oct 4 22:20 .bash_history
-rwxr-xr-x+ 1 svgr2 Kein 2717 Oct 4 20:28 .bashrc
...
$ echo Hello >hello.txt # create file hello.txt with content Hello
$ ls -la # show new file exists in $HOME
total 203
-rw-r--r-- 1 svgr2 Kein 6 Oct 7 23:38 hello.txt
...
$ cat hello.txt # output content of file
Hello
```
1. Open Windows file explorer (
[ ? ](https://geekflare.com/wp-content/uploads/2021/06/14-alternative-file-managers-to-replace-windows-10-file-explorer.jpg)
) and navigate to file `hello.txt`.
Open the file by clicking (ending `.txt` should open the
file with *notepad*).
1. Return to *bash* terminal:
- change to HOME-directory and
- open file `.bashrc`
```sh
$ cd # change to bash HOME-directory
$ ls -la # find file .bashrc
total 203
-rwxr-xr-x+ 1 svgr2 Kein 2717 Oct 4 20:28 .bashrc
$ cat .bashrc # output file .bashrc
...
```
## 2. Configure paths in `.bashrc`
[PATH](https://en.wikipedia.org/wiki/PATH_(variable)) is an
environment variable on Unix-like operating systems that
specifys a set of directories where executable programs are
located. A *"command not found"* error occurs when PATH is
not properly configured.
1. Open `.bashrc` using an editor, e.g. *vim* and append PATH
configurations.
```sh
$ vim .bashrc # open .bashrc in vim editor
```
1. Append PATH configurations at the end of the file - only
those relevant on your system - and djust paths for your
system:
```sh
# add Windows system paths
export PATH=".:/usr/bin:/usr/local/bin"
export PATH="${PATH}:$(cygpath ${SYSTEMROOT}):$(cygpath ${SYSTEMROOT})/system32"
# add Java path
export JAVA_HOME="/c/Program Files/Java/jdk-21"
export PATH="${PATH}:${JAVA_HOME}/bin"
# add Python path
export PYTHON_HOME="/c/Users/svgr2/AppData/Local/Programs/Python/Python312"
export PATH="${PATH}:${PYTHON_HOME}"
export PATH="${PATH}:${PYTHON_HOME}/Scripts"
# add Docker path
export DOCKER_HOME="/c/Program Files/Docker/Docker"
export PATH="${PATH}:${DOCKER_HOME}/resources/bin"
...
```
1. Verify paths have been added to *PATH* variable:
```sh
$ source .bashrc # reload .bashrc to activate chances
$ echo $PATH # show PATH
.:/usr/bin:/usr/local/bin:/c/WINDOWS:/c/WINDOWS/system32:/c/Program ...
$ echo $PATH | tr ':' '\n' # pretty print PATH
.
/usr/bin
/usr/local/bin
/c/WINDOWS
/c/WINDOWS/system32
/c/Program Files/Java/jdk-21/bin
/c/opt/maven/bin
/c/Users/svgr2/AppData/Local/Programs/Python/Python312
/c/Users/svgr2/AppData/Local/Programs/Python/Python312/Scripts
/c/Program Files/Docker/Docker/resources/bin
/c/Program Files/MySQL/MySQL Workbench 8.0 CE
/c/Program Files (x86)/Git/bin
/c/Program Files/Oracle/VirtualBox
/c/opt/Qt6/Tools/mingw1120_64/bin
/c/opt/Qt6/6.2.4/mingw_64/bin
```
Paths may vary based on your system.
1. Start programs to verify paths have properly been set.
```sh
$ java --version
java 21 2023-09-19 LTS
Java(TM) SE Runtime Environment (build 21+35-LTS-2513)
Java HotSpot(TM) 64-Bit Server VM (build 21+35-LTS-2513, mixed mode, sharing)
$ python --version
Python 3.12.0
$ docker --version
Docker version 24.0.6, build ed223bc
```