= 2025-07-18 (Friday) = 

In my quest to re-live the glory days of Unix shared systems I
looked at using "write" to communicate with other logged in users
(i.e. me, on another PTS)

I found it wouldn't work:

write: effective gid does not match group of /dev/pts/1

Apparently the write command is broken due to its permissions not
being correct anymore, due to security concerns.... a normal user
can't run it...

I found the answer to set gid (chmod 02755):


-----------------------8<------------------------------------------

chown root:tty /usr/bin/write

chmod 02775 /usr/bin/write

---------------------------------------->8-------------------------


It now works as expected!

I can talk to myself in two separate login windows.