Re: is hard-coding the group name, "tty", portable enough for who -a?

[Eric Blake]

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According to Jim Meyering on 7/7/2008 6:52 AM:
| If anyone can find a system on which this prints
| something other than "tty", please let us know:
|
|   stat --format %G $(tty)

On cygwin 1.5.25, this prints "None".  By default, cygwin has neither a
'root' nor a 'tty' group, so cygwin punts and chooses the only group name
that is guaranteed to exist on underlying Windows.  Meanwhile, wall is
installed with the permissions of the user who ran the cygwin installer:

$ ls -lF /usr/bin/wall $(tty)
- -rwxrwxrwx+ 1 eblake Users 8192 Apr  1 01:55 /usr/bin/wall.exe*
crw-rw-rw- 1 eblake None 136, 0 Nov 30  2006 /dev/tty0
$ id
uid=1007(eblake) gid=513(None) 513(None),544(Administrators),545(Users)

There is no /usr/bin/write on cygwin, and I've never tried using wall to
see whether terminal messaging is even reasonable to expect to work.

It may just be that worrying about 'who -a' on cygwin is not worth the
effort, since I'm not sure whether terminal messaging is supported.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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