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Written by Oleksandr Gavenko (AKA gavenkoa), compiled on 2020-11-21 from rev ebbf146d86c1+.

Cygwin.

Configuration

Run setup.exe. Today you should prefer 64-bit flavor because it sould less BLODA. Add Cygwin /bin directory to your PATH env var:

set PATH=c:\opt\cygwin\bin;%PATH%

Cygwin behavior can be altered via CYGWIN env var:

set CYGWIN=nodosfilewarning noglob

Currently only noglob is useful. It disables interpreting special shell wildcard characters passed verbatim from native Windows apps. So you will unable to do ls * from cmd.exe. But without this option (glob is default) Mercurial patterns, like {rev} are broken. For me native Windows Emacs can't determine file revision with my hg wrapper.

https://cygwin.com/cygwin-ug-net/using-cygwinenv.html
The CYGWIN environment variable. Available options.

Set HOME env var:

set HOME=c:\home
https://stackoverflow.com/questions/1494658/how-can-i-change-my-cygwin-home-folder-after-installation
How can I change my Cygwin home folder after installation?

Set TMP and TEMP env vars without dangerous symbols in path (without spaces, etc):

set TMP=c:\tmp
set TEMP=c:\tmp

Also you need to edit /etc/passwd to point to correct home path.

For Cygwin 1.7 /etc/nsswitch.conf settings is used to define user home. By default it is /home/%U so it is better to create symlink:

$ ln -s /cygdrive/d/home /home/user

Alternatively with native Windows symlink (from build-in cmd command):

cmd# mklink /D c:\opt\cygwin\home\user c:\home

List of installed packages (-c - check, -d - dump only):

$ cygcheck -c -d

Alternatively look to file content:

/etc/setup/installed.db

In a past I work with particular code point:

set LANG=ru_RU.cp1251

Altering LANG for anything other then C cause only problems, when you get help and error messages in non-English. It is mostlry impossible to search for keywords, when text are translated.

Documentation

Cygwin C API man pages and user guide manuals available in cygwin-doc package.

Documentation unpacked to /usr/share/doc/cygwin-... directory.

apt-cyg package manager

apt-cyg is based on bash, wget, tar, gawk and bzip2 packages and provide convenient commands for managing and queries packages:

$ apt-cyg update
$ apt-cyg install emacs-w32
$ apt-cyg remove emacs-w32

Information about package and dependencies:

$ apt-cyg show emacs-w32
$ apt-cyg depends wget
$ apt-cyg rdepends emacs

List installed packages:

$ apt-cyg list

Search for package with file across installed packages:

$ apt-cyg search stdio.h

List package files for installed packages:

$ apt-cyg listfiles util-linux

Search for package with file through cygwin.com:

$ apt-cyg searchall stdio.h

List all packages in setup.ini:

$ apt-cyg listall

Find package by regex:

$ apt-cyg listall ^emacs

To switch between mirrors:

$ apt-cyg mirror ftp://ftp.cygwinports.org/pub/cygwinports
$ apt-cyg update
$ apt-cyg install php

$ apt-cyg mirror ftp://www.fruitbat.org/pub/cygwin/circa/2016/08/30/104223

$ apt-cyg mirror http://mirrors.kernel.org/sources.redhat.com/cygwin/

Just switching mirror does not update metadata.

To change a location of directory where packages and setup.ini downloaded:

$ apt-cyg cache
C:\net

$ apt-cyg cache ~/net
Cache set to C:\home\net.
https://github.com/kou1okada/apt-cyg
Still maintained project with extra features.
https://github.com/transcode-open/apt-cyg/
Home page of abandoned project.
https://github.com/transcode-open/apt-cyg/issues/19
Request to support multiply sources.
http://stackoverflow.com/questions/22411162/how-to-add-a-repository-using-apt-cyg/
How to add a repository using apt-cyg.
https://odoepner.wordpress.com/2012/12/06/install-cygwin-and-cygwinports-packages-using-apt-cyg/
Depricated way to install from several sources with -m option using shell aliases as a trick.

Cygwin bash completion

Cygwin bash has extra patch that adds completion_strip_exe option:

shopt -s completion_strip_exe

If you complete executable .exe suffix is stripped if any. That halps with bash-completion because usually comletion defined for base name without .exe suffix, like:

complete -F _figlet figlet
https://github.com/cygwinports/bash
7b. completion_strip_exe - using 'shopt -s completion_strip_exe' makes completion strip .exe suffixes.

Cygwin file permission

Get list of permissions:

$ getfacl .

rsync without problems:

$ rsync -ar —chmod=ugo=rwX $FROM/ $TO/
https://cygwin.com/cygwin-ug-net/using-filemodes.html
File permissions.
https://cygwin.com/cygwin-ug-net/ntsec.html
POSIX accounts, permission, and security.
https://stackoverflow.com/questions/5828037/cygwin-sets-file-permission-to-000
Cygwin sets file permission to 000.

Installation on Windows XP

Cygwin from v2.5.5 and Setup version 2.874 (on 25 Aug 2016) is latest version with Windows XP support. Later versions build with dependencies on newer syscalls and failt to run in Windows XP.

Latest mirrors avaialble at fruitbat.org:

To run setup against this mirror:

cmd> setup.exe

setup.exe available at:

Run as (-X disable signature verification, -s <url> option select a particular mirror, -O option disallow any other mirrors):

cmd> setup-x86.exe -X -s ftp://www.fruitbat.org/pub/cygwin/circa/2016/08/30/104223 -O
http://www.fruitbat.org/Cygwin/timemachine.html
Description of Cygwin time machine project.
http://stackoverflow.com/questions/39479826/cygwin-2-5-2-mirror-getting-the-last-xp-release
Question about Cygwin old mirror.
http://superuser.com/questions/1132000/is-it-still-possible-to-get-cygwin-for-xp
Question about Cygwin old mirror.
http://cygwin-xp.portfolis.net/
Another old mirror.

Cygwin ports

This project provides Cygwin binary and source packages for a large variety of programs and libraries, including the GNOME and KDE desktop environments

http://cygwin-ports.sourceforge.net/
Newest home of the Cygwin Ports project.
http://sourceware.org/cygwinports/
Home page.
http://cygwinports.blogspot.com
Official blog.
https://github.com/cygwinports
cygport scripts to compile cygwinports
https://github.com/cygwinports/cygport
Source packaging tool for Cygwin
https://cygwinports.github.io/cygport
Cygport Reference Manual.

Which Cygwin version you run?

$ uname -r
1.7.7(0.230/5/3)
$ cygcheck -c cygwin
Cygwin Package Information
Package              Version        Status
cygwin               1.7.7-1        OK

Rebase dll

In order to Cygwin to maintain fork() syscall it should preserve same logical base address for dll to be able to share library between child and parent process. It was done via special hints in dlls.

With new version of Cygwin software or external Windows libraries (AntiVirus may inject its their libraries into Cygwin process address space) it may happen that new library is overlapped with existing.

There is rebase utility that changes base address hints for dll.

You should finish all Cygwin processes in order to rebase to succeed.

You may trigger automatic rebase of all packages in next run of setup.exe with:

$ rebase-trigger full

Read more at:

https://cygwin.com/faq/faq.html#faq.using.fixing-fork-failures
How do I fix fork() failures?
https://chromium.googlesource.com/chromium/src/+/master/docs/cygwin_dll_remapping_failure.md
Handling repeated failures of rebaseall to allow cygwin remaps.

Recreate /etc/passwd and /etc/groups.

$ mkpasswd -d | grep $yourlogin > /etc/passwd  # if you in Windows domain
$ mkpasswd -l > /etc/passwd                    # if you in Windows domain

$ mkgroup -l > /etc/group

Adding mount points

In Cygwin the 3rd parameter (FS type) has special meaning:

/etc/fstab:

none /cygdrive    none binary,posix=0,user,noacl 0 0
c:/opt/   /opt    none binary,noacl,user,posix=0 0 0
d:/backup /backup none binary,noacl,user,posix=0 0 0
/var     /usr/var none bind
https://cygwin.com/cygwin-ug-net/using.html#mount-table
The Cygwin Mount Table. Description of supported keys.

Running X Window.

$ XWin -multiwindow&

or:

$ XWin -clipboard -silent-dup-error -xkblayout "us,ru" -xkboptions "grp:caps_toggle"&

To start X application you must set 'DISPLAY':

$ DISPLAY=:0 xterm&

Working with packages.

List of package files.

$ cygcheck -l pkg-name

Search packages by containing path (only under installed packages).

$ for f in /etc/setup/*.lst.gz; do gzip -c -d $f | grep $WORD  2>&1 >/dev/null && { echo $f; break; } || :; done

Search for package.

If you have file name or regex use (need internet connection):

$ cygcheck -p REGEX

cygcheck use such link:

http://cygwin.com/cgi-bin2/package-grep.cgi?grep=REGEX

Cygwin installation info.

$ uname -a
$ cygcheck -s -r

Cygwin acronyms.

http://www.cygwin.com/acronyms
One encounters all sorts of acronyms on the Cygwin mailing lists.

Check dll dependency.

$ ldd my.dll
$ ldd my.exe
$ cygcheck ./my.dll
$ cygcheck ./my.exe

Cygwin alternatives.

http://www.suacommunity.com/SUA.aspx
Subsystem for Unix-based Applications and Services for Unix