cygwrun

Run windows applications under Posix environment

Overview

Cygwin uses posix paths and environments which makes most of the standard windows programs to fail because of path mismatch. The traditional way of handling that is using Cygwin cygpath utility which translates Cygwin (posix) paths to their windows equivalents from shell.

For example a standard usage would be:

program.exe "--f1=`cygpath -w /tmp/f1`" "`cygpath -w /usr/f1`" ...

This can become very complex and it requires that the shell script is aware it runs inside the Cygwin environment.

cygwrun utility does that automatically by replacing each posix argument that contains path element with its windows equivalent. It also replaces paths in the environment variable values making sure the multiple path elements are correctly separated using windows path separator ;.

Using cygwrun the upper example would become:

cygwrun program.exe --f1=/tmp/f1 /usr/f1 ...

Before starting program.exe cygwrun converts all command line and environment variables to windows format.

Usage

Here is what the usage screen displays

Usage cygwrun [OPTIONS]... PROGRAM [ARGUMENTS]...
Execute PROGRAM [ARGUMENTS]...

Options are:
 -r <DIR>  use DIR as posix root
 -w <DIR>  change working directory to DIR before calling PROGRAM
 -k        keep extra posix environment variables.
 -K        keep trailing path separators for paths.
 -f        convert all unknown posix absolute paths
 -n <ENV>  do not translate ENV variable(s)
           multiple variables are comma separated.
 -s        do not translate environment variables.
 -S        do not translate arguments.
 -q        do not print errors to stderr.
 -v        print version information and exit.
 -V        print detailed version information and exit.
 -h | -?   print this screen and exit.
 -p        print arguments instead executing PROGRAM.
 -e        print environment variables matching ARGUMENTS
           if no ARGUMENTS are provided print all variables.

Posix root

Posix root is used to replace posix parts with posix environment root location inside Windows environment.

Use -r <directory> command line option to setup the install location of the current posix subsystem.

In case the -r <directory> was not specified, the program will check the following environment variables:

First it will check POSIX_ROOT and then CYGWIN_ROOT variable. If none of them were defined, cygwrun will search for bash.exe and its root directory will be used.

Make sure that you provide a correct posix root since it will be used as prefix to /usr, /bin, /tmp constructing an actual Windows path.

For example, if Cygwin is installed inside C:\cygwin64 you can set either environment variable

    $ export CYGWIN_ROOT=C:/cygwin64
    ...
    $ cygwrun ... --f1=/usr/local

... or declare it on command line

    $ cygwrun -r C:/cygwin64 ... --f1=/usr/local

In both cases --f1 parameter will evaluate to --f1=C:\cygwin64\usr\local

Environment variables

Any Cygwin program that calls Cygwrun, will already translate most of the known environment variables to Windows format, but not all of them.

Cygwrun presumes that it's called from some Cygwin process, and it will try to translate all environment variables from posix to windows notation.

For example, if environment variable contains valid posix path(s) it will be translated to windows path(s).

    $ export FOO=/usr:/sbin:../dir
    $ cygwrun -e FOO
    $ FOO=C:\cygwin64\usr;C:\cygwin64\sbin;..\dir

However in case the environment variable value contains path element that cannot be translated to windows path, the original value is preserved, regardless if all other path elements can be translated.

    $ export FOO=/usr:/sbin:/unknown:../dir
    $ cygwrun -e FOO
    $ FOO=/usr:/sbin:/unknown:../dir

The -f command line option forces all absolute posix paths to be converted to it's windows format.

    $ export FOO=/usr:/sbin:/unknown:../dir
    $ cygwrun -f -e FOO
    $ FOO=C:\cygwin64\usr;C:\cygwin64\sbin;C:\cygwin64\unknown;..\dir

Note that some environment variables are allways removed from the current environment variable list that is passed to child process, such as CYGWIN_ROOT or PWD.

The full list of variables that are allways removed is defined with removeenv[] array in cygwrun.c source file.

Command line arguments

All arguments passed to PROGRAM are converted to windows format.

If argument is not a path, or it starts with --, and then followed by valid variable name and equal = character, data after the equal character will be translated to windows path. If translation fails, the original argument will be preserved.

    $ cygwrun -p A=/tmp
    $ A=C:\cygwin64\tmp
    $
    $ cygwrun -p --A=/tmp
    $ --A=C:\cygwin64\tmp

License

The code in this repository is licensed under the Apache-2.0 License.