Você pode verificar esta ou melhor, você pode verificar man
page para screen
que é uma boa referência e diz:
backtick id lifespan autorefresh cmd args...
backtick idProgram 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. Theautorefresh
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 thelifespan
and theautorefresh
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.
De acordo com seu exemplo, você pode adicionar:
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