I recently dicover the genmon plugin, when i try the command line : uptime | awk {'print $10'} | sed 's/,//g' The plugin don't works and shows "xxx" instead of the uptime like "0.30" If i create a Shell script name script.sh with : #/bin/bash uptime | awk {'print $10'} | sed 's/,//g' And insert the script in the plugin's command line, it works well.
That's because the command in the properties dialog is not a sub-shell or shell. Genmon is written with the spirit to use scripts, you can find several script examples in the source directory and on the goodies wiki page.
As mike said, genmon doesn't try to behave like a shell, so this kind of niceties provided by a shell are not available. To get them, you have to write a script.
I had also like to specify, if you do a mistake you won't get any error messages, and basically you can screw your system. For shell related commands, prefer a script or a terminal.