strange shell output using tcsh under Cygwin

Will Parsons wbp@nodomain.invalid
Mon Nov 6 00:15:00 GMT 2017


Under Unix-type platforms, checking on what the PATH variable is set to is
pretty easy - I typically use "env" and the displayed value of PATH is easily
parsed by eye.  Under Cygwin/Windows, one can do the same, but the value of
PATH is more likely to be considerably more complicated and harder for a
human to parse.  For example, this is what I see on my local machine under
Cygwin:

   PATH=/usr/local/bin:/usr/bin:/c/Windows/system32:/c/Windows:/c/Windows/system32/wbem:/c/ProgramData/Oracle/Java/javapath:/c/Program Files/Common Files/Microsoft Shared/Windows Live:/c/Program Files (x86)/Common Files/Microsoft Shared/Windows Live:/c/Program Files/Dell/DW WLAN Card:/c/Program Files (x86)/Intel/iCLS Client:/c/Program Files/Intel/iCLS Client:/c/Windows/System32/WindowsPowerShell/v1.0:/c/Program Files/WIDCOMM/Bluetooth Software:/c/Program Files/WIDCOMM/Bluetooth Software/syswow64:/c/Program Files (x86)/Windows Live/Shared:/c/Program Files (x86)/Bazaar:/c/Program Files (x86)/QuickTime/QTSystem:/c/cygwin/home/william/bin:/c/ezwinports/bin:/c/Program Files (x86)/PuTTY:/usr/lib/lapack:/usr/sbin:/c/msys/1.0/local/bin

I thought it would be nice to write a simple script to make this more
comprehensible by breaking the path into separate lines, and so wrote the
following trivial script:

   #!/bin/sh
   echo $PATH | tr ':' '\n'

Oddly though, it does not give the expected results under Cygwin.  Running
this script under Cygwin under my normal interactive script (tcsh) yields the
following:

   % ./path
   /usr/local/bin
   /usr/bin
   /bin
   /usr/sbin
   /c/Windows/system32
   /c/Windows
   /c/Windows/system32/wbem
   /c/ProgramData/Oracle/Java/javapath
   /c/Program
   Files/Common
   Files/Microsoft
   Shared/Windows
   Live
   /c/Program
   Files
   (x86)/Common
   Files/Microsoft
   Shared/Windows
   Live
   /c/Program
   Files/Dell/DW
   WLAN
   Card
   /c/Program
   Files
   (x86)/Intel/iCLS
   Client
   /c/Program
   Files/Intel/iCLS
   Client
   /c/Windows/System32/WindowsPowerShell/v1.0
   /c/Program
   Files/WIDCOMM/Bluetooth
   Software
   /c/Program
   Files/WIDCOMM/Bluetooth
   Software/syswow64
   /c/Program
   Files
   (x86)/Windows
   Live/Shared
   /c/Program
   Files
   (x86)/Bazaar
   /c/Program
   Files
   (x86)/QuickTime/QTSystem
   /c/cygwin/home/william/bin
   /c/ezwinports/bin
   /c/Program
   Files
   (x86)/PuTTY
   /usr/lib/lapack

Clearly the path is being broken using spaces as well as colons.

Even thoush the shell script itself explicitly specifies "/bin/sh", the
result seems to depend on the shell being used to invoke it.  Using Cugwin
bash, the same script results in the following:

   sothis$ ./path
   /usr/local/bin
   /usr/bin
   /c/Windows/system32
   /c/Windows
   /c/Windows/system32/wbem
   /c/ProgramData/Oracle/Java/javapath
   /c/Program Files/Common Files/Microsoft Shared/Windows Live
   /c/Program Files (x86)/Common Files/Microsoft Shared/Windows Live
   /c/Program Files/Dell/DW WLAN Card
   /c/Program Files (x86)/Intel/iCLS Client
   /c/Program Files/Intel/iCLS Client
   /c/Windows/System32/WindowsPowerShell/v1.0
   /c/Program Files/WIDCOMM/Bluetooth Software
   /c/Program Files/WIDCOMM/Bluetooth Software/syswow64
   /c/Program Files (x86)/Windows Live/Shared
   /c/Program Files (x86)/Bazaar
   /c/Program Files (x86)/QuickTime/QTSystem
   /c/cygwin/home/william/bin
   /c/ezwinports/bin
   /c/Program Files (x86)/PuTTY
   /usr/lib/lapack
   /usr/sbin
   /c/msys/1.0/local/bin

For comparison, I tried running the same script under FreeBSD (where tcsh is
also my normal interactive shell).  Since paths with spaces are quite rare
under Unix-type systems, I added a dummy 'x x' (imaginary directory) to the
path.  The result was as follows:

   % ./path
   /sbin
   /bin
   /usr/sbin
   /usr/bin
   /home/william/bin
   /home/william/.gem/ruby/2.3/bin
   /usr/local/sbin
   /usr/local/bin
   x x

So, I am quite puzzled.

-- 
Will


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