Friday, January 16, 2009

Using top, mytop, mysql command-line all inside screen

This posting contains sample .screenrc and .mytop files.

If you've never used screen before and you like using command-line things, check it out. What I like most about screen is you can start a screen session, detach from it intentionally or otherwise, then reattach picking up right where you left off last time. The easiest way to explain what screen does is simply stating that screen allows you to open (within reason) as many independent terminal sessions as your system will allow. From each of these sessions, you can do pretty much anything you'd do from your regular terminal session. Some of these sessions can be displayed back to you at the same time, some may be left running in the background. In each session, however, screen tracks the session display just like a regular terminal would.

I use screen personally to help me be aware of what's happening critically on my system, and to provide a constant point of reference I can get back to where I left off when I'm able.

The top command is widely used by system administrators to see what processes are taking up the most resources on a given system. Like top, mytop also helps DBA's to see what threads are utilizing resources quickly. What many don't know is there are a number of things that can be done with mytop like killing active processes, turning off the header, setting up color, etc.

When you combine these features with screen, it can be a very nice tool when doing administration and development of a database host.

For example, over a telnet (very insecure) or ssh session, screen can present multiple session windows back to the user all, without needing a gui at all.

My own .screenrc automatically sets up my windows for me like this:

At the top, I automatically start top in a window that's 10 lines high. This lets me see the most process-intensive commands running at any given time.

The window below that is a mytop session to the database and shows me a list of the active queries at any given time (I filter out sleeping sessions and I don't generally display the headers giving me more space to see what queries are running. I also have it updating once per second.

In the third (bottom) window, I leave the rest of the lines to interact with MySQL, the shell, and other systems.

You'll probably find these files interesting:

$HOME/.mytop: (note: chmod 600 to protect your password from prying eyes)




# Make the escape key the backtick rather than ctrl-a since I use ctrl-a so much
escape ``
termcapinfo linux|xterm|rxvt|xterm-color ti@:te@:XT
autodetach on
autonuke on
defflow off
defscrollback 3000 # yes, that's lines
startup_message off
vbell on
vbell_msg "bell on %t (%n)"

caption splitonly "%{= bw}%-Lw%{= wb}%50> %n%f* %t %{-}%+Lw"

hardstatus alwayslastline "%< %= %{= bw} %H %{= rW} %l %{= bw} %m/%d %0c:%s %{-}"

activity "Activity in %t(%n)"

shelltitle "shell"

# Toggle 'fullscreen' or not.
bind f eval "caption splitonly" "hardstatus ignore"
bind F eval "caption always" "hardstatus alwayslastline"

# escape Control-R will reset my windows back to start-up sizes and locations.
# It's nice for when I disconnect from screen then reconnect because screen
# doesn't split windows by
# default.
bind ^R eval "only" "select 0" "split" "split" "focus top" "resize 10" "focus down" "select 1" "resize 12" "focus bottom" "select 2"

# If a window goes unresponsive, don't block the whole session waiting for it.
nonblock on

bufferfile /home/me/screenPasteBuffer.txt

msgwait 0
screen -t top 0
stuff "nice top \012"
screen -t mytop@dbdev 1
stuff "nice mytop \012"
screen -t webdev001 2
focus top
select 0
resize 10
focus down
select 1
resize 12
focus bottom
screen -t dbdev001 3
stuff "ssh dbdev001"
screen -t dbreport001 4
stuff "ssh dbdev001"
screen -t webdev001 5
stuff "ssh dbdev001"
screen -t webdev001 6
stuff "ssh dbdev001"
select 2
msgwait 2

pow_detach_msg "Screen session of \$LOGNAME \$:cr:\$:nl:ended."
shell -$SHELL


I can't take credit for all these enhancements. On the other hand, I have tweaked them to suit my own needs.



  1. I would also point you to innotop, which is a full superset of mytop's capabilities.

  2. Baron - I had never heard of innotop but will gladly give it a try - thanks for the tip. :-) I've been using mytop for years and find it to be quite powerful already, but innotop makes the claim that it's added *lots* of features. To learn more, check out I will post again after I have a chance to try it for myself.

  3. Baron - I do like innotop - it's certainly worth a look-at for others. Thanks for visiting and commenting. :-)