10

Edit: Issue has been resolved after update to Git for Windows >= 2.9.0.windows1

Disclaimer

Some comments are referring to full "story" behind this issue but I decided to shorten it because it was getting too long and hard to follow. I present you as succinct failing example as possible. For those who are interested in knowing full context of the problem: it is available in previous revision of the question.

This: basedir=$(dirname "$(echo "$0" | sed -e 's,\\,/,g')") is the first (excluding hashbang) line in scripts generated by npm after installing any package which comes with CLI. For some reason basedir is incorrectly resolved and that's why node can't find module and crashes. I managed to narrow down problem to the pipe in subshell on latest Git for Windows' git-bash. Executing:

echo -n "1:"
echo "a" | cat
echo -n "2:"
echo "$(echo "a" | cat)"
echo -n "3:"
echo "$(echo "a")"

prints:

1:a
2:
3:a

I can't find other people with this issue so I think that it's something wrong with my env (Windows 10 Pro, Git for Windows 2.8.4) and personally I'm out of ideas where it might come from. My findings:

  • downgrading Git for Windows to 2.6.4 fixes the problem. Still I don't like being stuck on old version ;/
  • it works fine on clean Windows 10 VM
  • pipe output seems to be completely empty because running following snippet doesn't return any result.
  • On clean installation of mingw + msys problem doesn't occur

snippet:

echo $(echo foobar | cat > bazzzzzzzzzz ; ) ; cat bazzzzzzzzzz
find /c -name bazzzzzzz* 2> /dev/null # /c, /d and /x are my Windows partitions
find /d -name bazzzzzzz* 2> /dev/null # I did test if it actually works for existing file and it does
find /x -name bazzzzzzz* 2> /dev/null

Thanks to agc for invaluable help on figuring this out to this point.

My PATH variable looks like this:

PATH=/c/Users/ja/bin:/mingw64/bin:/usr/local/bin:/usr/bin:/bin:/mingw64/bin:/usr/bin:/c/Users/ja/bin:/c/Windows:/c/Windows/System32:/c/Windows/System32/Wbem:/c/Windows/System32/WindowsPowerShell/v1.0:/c/Program Files/nodejs:/c/ProgramData/Oracle/Java/javapath:/c/program files/graphicsmagick-1.3.23-q16:/c/ProgramData/chocolatey/lib/getopt/binaries:/c/Program Files (x86)/Windows Kits/8.1/Windows Performance Toolkit:/c/Program Files/nodejs:/c/Program Files (x86)/Microsoft VS Code/bin:/c/Users/ja/AppData/Roaming/npm:/c/Program Files (x86)/MacType:/usr/bin/vendor_perl:/usr/bin/core_perl

also

$ which sed
/usr/bin/sed
$ which echo
/usr/bin/echo
$ which cat
/usr/bin/cat
$ echo $SHELL
/usr/bin/bash
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16
  • 1
    Indeed it's not needed in this case, but as I said this script is automatically generated during installation of node package through npm so manually modifying such scripts after every installation almost defeats the idea of using package manager. I also ruled out npm from potential sources of the issue because I can't find anyone struggling with such problem on the internet. Thanks for comment tho :) Commented Jun 5, 2016 at 17:49
  • 1
    It's acting as though instead of invoking plain sed it is invoking sed -n, i.e., a version of sed that prints nothing unless explicitly told to print something (or just a completely broken command that always prints nothing). Commented Jun 5, 2016 at 21:26
  • 2
    Try swapping out echo "$0" | sed -e 's,\\,/,g' with echo "$0" | tr '\\' '/'. Commented Jun 6, 2016 at 6:45
  • 1
    Both errors have something like $( foo | bar ), so the next step is to see if you can simplify that. Does $( foo ) alone work? If it does, maybe it's the pipe, so try $( foo | cat ). Commented Jun 6, 2016 at 15:31
  • 1
    Ok, so we know that pipes work, simple command substitution works, but a command substitution with a pipe fails -- or perhaps sends the output to some place other than STDOUT. To test that try echo $(echo foobar | cat > baz ; ) ; cat baz Commented Jun 6, 2016 at 16:42

2 Answers 2

Reset to default
2

Summarizing the comments, the short (tl;dr) version: either downgrade, upgrade, and/or re-install MSYS and MinGW that come with Git for Windows.

MSYS supplements MinGW, and the version provided by Git for Windows may be modified from the original maintainers of MSYS. There was a bug reported against MSYS for what appears to be this same issue (using "mingw version: 64 bit bundled with git version 2.8.3.windows.1"), but was marked as "works for me" (i.e., "can't reproduce"). But there was a comment that the problem could be in the repackaging:

"Please be advised that MSYS, as bundled with git for windows, may be modified from our official distribution, (and 64-bit MinGW certainly isn't ours); thus we don't formally support either of these." https://sourceforge.net/p/mingw/bugs/2303/

Long story short, looks like a bug.

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Comments

0 
basedir=$(dirname "$(echo "$0" | sed -e 's,\\,/,g')")

This seems like an example of the XY problem. Let us break down this line:

echo "$0"

This is usually the path to the script, for example ./alfa.sh

sed -e 's,\\,/,g'

This replaces backslashes with forward slashes. This is where this line starts to fall apart:

  1. You dont need the -e, you can just do sed 's,\\,/,g'

  2. You probably dont need the g, usually just going to be one slash as shown above

  3. Changing the slashes doesnt really make sense. Bash, even on Windows, is going to be using forward slashes already

  4. If for some reason the slashes do need to be changed, Sed is not the right tool for this anyway, cygpath is:

    $ cygpath -m 'C:\Program Files\Mozilla Firefox\firefox.exe'
C:/Program Files/Mozilla Firefox/firefox.exe

dirname

Now you are calling dirname after sed/cygpath. It should be called before, that way sed/cygpath dont have to replace as much:

basedir=$(cygpath -m "$(dirname "$0")")

Finally, the sed command is bad for another reason; if you are going to be spitting out a path, it should be an absolute one, because why not?

basedir=$(cygpath -am "$(dirname "$0")")

Notice now that no pipe is even involved. I will also add that this problem was introduced recently to the NPM repo. You might comment to the devs there.

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5 Comments

Thank you for such verbose answer but as I mentioned before: these scripts are generated by npm. What you are proposing is workaround - not using pipe. I simply cannot do this without manually editing each generated script. What I am asking for is hints/clues/ideas of why such scripts are not working only on my machine. With help of stackoverflow community I managed to narrow scope of the issue to pipe in the subshell. This is why I don't think it's XY problem. Also I'm not negating that usage of sed here is at least questionable :)
While I understand that usage of pipe and sed in these scripts may be inappropriate the fact is that it works as intended for everyone else. I stumbled upon this while trying to execute npm package but it's more generic as it can potentially break every sh script evaluated on my machine and npm has nothing to do with that. If I were to go to the root of the problem I would go to Git for Windows repo but still it does work on clean VM so I don't think that task of guessing potential causes is a right fit for their issue tracker. Asking SO community seems to be a better bet
@bgoscinski you still have yet to provide a valid example that needs a pipe. cat is a NOOP in your first example, and the sed example can be reworked with cygpath ditching the pipe. If you want an answer give an example that actually requires a pipe. Just saying "i want this because i want it" is not groovy
I wan't it because npm's or any other similar script will fail on my machine. Isn't it enough for you?
@Sierra, that a pipe doesn't work is itself more interesting than the code that borders the pipe. Really it's more of an XY(Z) problem where XY leads to discovering Z, after which XY are both dwarfed by Z.

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