filesystem: remove /usr/bin/cmd

[lazka]

It's not clear why it is there (except for changing COMSPEC somehow, but why?), and it's causing problems such as python/cpython#127001

Ideas what this could break welcome.

[lazka]

@Alexpux do you happen to know why we have /usr/bin/cmd?

[smalltalkman]

I estimate that deleting cmd will cause many software builds to fail, you can refer to: rmyorston/busybox-w32#297 (comment)

[lazka]

I estimate that deleting cmd will cause many software builds to fail, you can refer to: rmyorston/busybox-w32#297 (comment)

What would removing /usr/bin/cmd change there? Wouldn't cmd.exe not behave the same?

[smalltalkman]

I estimate that deleting cmd will cause many software builds to fail, you can refer to: rmyorston/busybox-w32#297 (comment)

What would removing /usr/bin/cmd change there? Wouldn't cmd.exe not behave the same?

Removing /usr/bin/cmd will cause cmd //c echo "$1" to enter the cmd console and hang.

The main purpose of func_convert_core_msys_to_w32 is to use cmd in cygwin (msys) to convert unix paths to w32 paths. For example, in my msys2 (under win7, not necessarily the latest):

lenovo@lenovo-PC MSYS /c/Users/lenovo/Desktop
# cmd //c echo /
D:/gym/softwares/msys64/

# cmd //c echo /abc/def
D:/gym/softwares/msys64/abc/def

# cmd //c echo /d/abc/def
D:/abc/def

# cmd //c echo d:\\abd
d:\abd

# cmd //c echo d:\abd
d:abd

# cmd //c echo d:/
d:/

These tasks cannot be accomplished by cmd.exe in Windows.

The above should only apply to cygwin (msys), not to busybox-w32. However, I had to use a script like the following to bypass this limitation in busybox-w32.

#!/bin/sh

if [ x"\$1" == x"//c" ]; then
  shift
  "\$COMSPEC" "/c" "\$@"
else
  "\$COMSPEC" "\$@"
fi

Additionally, the libtool commits related to cmd //c echo ... exist at autotools-mirror/libtool@d9033b1 and autotools-mirror/libtool@ac40b5f . These commits should explain the cause better.

[lazka]

Removing /usr/bin/cmd will cause cmd //c echo "$1" to enter the cmd console and hang.

Works fine here, what am I missing?

$ /C/WINDOWS/system32/cmd.exe //c echo "ok"
ok

[smalltalkman]

Removing /usr/bin/cmd will cause cmd //c echo "$1" to enter the cmd console and hang.

Works fine here, what am I missing?

$ /C/WINDOWS/system32/cmd.exe //c echo "ok"
ok

About one year ago, I encountered a similar problem. I remember that the test results at that time showed that cmd //c echo ... would hang, and I had to manually kill the cmd process to recover. I just retested it and the results showed that it did work. So please ignore the bad conclusion.

However, deleting /usr/bin/cmd will affect access to cmd when MSYS2_PATH_TYPE=strict is used, which makes PATH very small (I used to use this setting a lot, but rarely do now).