How can I add the session name to my screen status display?

Question

This is my current .screenrc files which is mostly copied from the link in the code

#First iteration 2014-09-06, not quite sure of stuff to add
# got a fancy hardstatus line noted below
hardstatus on
hardstatus alwayslastline
# hardstatus string "%w"

# blagged this hardstatus like from https://bbs.archlinux.org/viewtopic.php?id=55618, not quite sure what it does
hardstatus string '%{= kG}%{C}Screen: %{c}%{= kG}[%= %{= kw}%?%-Lw%?%{r}(%{W}%n*%f%t%?(%u)%?%{r})%{w}%?%+Lw%?%?%= %{g}][%{C} %d-%m %{W}%c %{g}]'

I now want the session name to appear in it as well, and the one I have settled on is from this answer - https://superuser.com/questions/212392/how-to-include-screens-session-name-in-hardstatus/212520#212520

The solution runs along these line:

hardstatus string '%H:%`'
backtick 0 30 30 sh -c 'screen -ls | grep --color=no -o "$PPID[^[:space:]]*"'

It is an area I am not familiar with and I wonder how the backtick command fits in it, ie whether it is a screen command at all.

Answer 1

You can check this or better you can check man page for screen which is a good reference and says:

backtick id lifespan autorefresh cmd args...
backtick id

Program the backtick command with the numerical id id. The output of such a command is used for substitution of the "%`" string escape. The specified lifespan is the number of seconds the output is considered valid. After this time, the command is run again if a corresponding string escape is encountered. The autorefresh parameter triggers an automatic refresh for caption and hardstatus strings after the specified number of seconds. Only the last line of output is used for substitution.
If both the lifespan and the autorefresh parameters are zero, the backtick program is expected to stay in the background and generate output once in a while. In this case, the command is executed right away and screen stores the last line of output. If a new line gets printed screen will automatically refresh the hardstatus or the captions. The second form of the command deletes the backtick command with the numerical id id.

As per your example you can add:

hardstatus string '%H:%1` | %2`'
backtick 1 30 30 sh -c 'screen -ls | grep --color=no -o "$PPID[^[:space:]]*"'
backtick 2 60 60 /usr/bin/uptime