What is Cygwin? Linux env for Windows

What Is Cygwin ?

Cygwin is a Linux-like environment under Windows.

Cygwin consists of:

• A DLL (cygwin1.dll) which acts as a Linux API emulation layer providing substantial Linux API functionality.
• A collection of tools which provide Linux look and feel.
• A bash console to interact

Standard Windows command line tools can even be intermixed within the UNIX/Linux shell script environment to administer the Windows system.

Management

Installation

• Download and run the setup.exe file.
• Choose the package. For instance:
  • Base
  • Devel packages to compile
  • Editors packages: If you would like to use emacs, xemacs, or vi/vim locally on your Windows computer.
  • httpd-tools: for the htpasswd utility if you create users files
  • bash-completion for bash completion
  • unzip for installer
  • jq for json (ie text) processing
  • …
• Set the following environment variables:
  • HOME to C:\User\username ¹⁾
  • EDITOR to your editor. For instance to notepad++
• Finish

Packages can be installed later by re-running Setup.exe.

Directory Structure

The installation directory (by default, c:\cygwin) is the root of the Unix-like file system, which contains bin, etc, home, tmp, and usr directories as would be found on a GNU/Linux or other Unix system.

After the Shell launch, the current (working) directory is the %HOME% env or by default the /home/user, where user is your Windows login name.

This choice is safe and usually shouldn't be changed. An fstab entry for them is not required.

How to begin / start the shell

To open a Cygwin terminal window:

• click on the Cygwin desktop icon,
• choose the Cygwin entry from your start menu,

Within this window, the GNU bash shell is running, with POSIX syntax (directory separators are '/', not '\').

The shell Cygwin.bat is located in the root installation directory of Cygwin.

@echo off

C:
chdir C:\cygwin64\bin

bash --login -i

Initially, the current (working) directory is /home/user, where user is your Windows login name.

Advantages

• Your environment variables (that contains generally secret) is stored in Windows and not in config files. You therefore will have less chance to commit them to Git.

Snippet

Path usage

Single Quote the windows path

cd 'c:\wherever'

More … https://cygwin.com/cygwin-ug-net/using-effectively.html#using-pathnames-effectively

Execute In Program files

"$(cygpath -u 'C:\Program Files\ojdkbuild\java-11-openjdk-11.0.15-1\bin\java.exe')" --version

Path conversion

# CYGINW == 1 if Cygwin is detected, else 0.
if [[ $(uname -a) =~ "CYGWIN" ]]; then
  CYGWIN=1
else
  CYGWIN=0
fi

# If Cygwin is detected, a DIR variable must be converted to Windows format.
(( CYGWIN )) && ADIR=$(cygpath --path --mixed "${ADIR}")

Support

My Windows logon name has a space in it

Don't use this directory if your Windows login name contains a space; make another and use that one instead, e.g., by typing these commands at the bash prompt:

mkdir /home/bob
echo "export HOME=/home/bob" >>.bashrc
echo "export HOME=/home/bob" >>.bash_profile
cp .bashrc .bash_profile /home/bob
echo "cd" >>.bashrc

Close your Cygwin terminal window and open another one; your current directory should now be /home/bob (or whatever you chose to call it). See the Cygwin FAQ (look for “My Windows logon name has a space in it”) for other solutions to this common problem.

Documentation / Reference

• http://cygwin.com
• An introduction to Cygwin