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Subject: Re: How to ensure that /bin takes priority over System32 with "bash
 -c"?
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From: Brian Inglis <Brian.Inglis@SystematicSw.ab.ca>
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Message-ID: <6f509ff1-af03-b166-be86-f457914fd33f@SystematicSw.ab.ca>
Date: Sat, 31 Oct 2020 13:46:55 -0600
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On 2020-10-31 08:21, Adam Dinwoodie wrote:
> On Sat, 31 Oct 2020 at 13:16, Matt D. via Cygwin wrote:
>> I can't always know what binaries exist in C:\Windows\System32 when
>> writing my scripts. Am I supposed to always launch scripts as "bash
>> --login -i -c"? I don't want or need to have bash run all of its login
>> scripts unnecessarily.
>>
>> How can I run my bash scripts without invoking it as a login shell and
>> ensure that /bin has the environment priority over System32 binaries?
> 
> Currently, your commands are doing exactly what you tell them: you're
> not doing anything to override the PATH from Windows, so they're using
> the PATH from Windows.
> 
> On a full Linux system, this is generally not an issue, because you
> won't have any processes trying to run as children of processes with
> Windows PATH variables. For most Cygwin users, this isn't a problem
> because they either (a) just accept the performance impact of running
> things with a login shell, or (b) (which I suspect is more likely) run
> most things from within a login shell or some other environment like
> cron that knows how to set the appropriate variables up.
> 
> If none of the above are options for you, you'll need to find some way
> to set the environment variables you need. This might just be starting
> your Bash commands with `export PATH=/bin:/sbin:$PATH`. Alternatively
> you could look at using the BASH_ENV environment variable; if you
> create, say, /etc/bashenv in Cygwin containing `export
> PATH=/bin:/sbin:$PATH` and any other commands you need, and set
> BASH_ENV=/etc/bashenv as a Windows system environment variable, I
> believe Bash should read that when started up in the way you're using
> it, and assuming you don't have any other non-Cygwin Bash programs on
> your system (e.g. from Git for Windows), I doubt it'd affect anything
> else.

Remember 'where' is like the Windows version of Cygwin which or whereis, so you
see only the Windows view of the current PATH:

$ where where /t
     33280   2019-03-18      22:46:08  C:\Windows\System32\where.exe

I export to the env or prefix any such commands, for example, commands that
start another mintty window in some arch, WSL distro, etc. or run a script in
one of those, with BASH_ENV=$HOME/.bash_env:

$ head ~/.bash_env
#|/bin/bash
# ~/.bash_env - set up bash environment for non-login non-interactive shells
export PATH="/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin:$PATH"

-- 
-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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