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Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.
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This one-liner is for cron jobs that need to provide some basic information about a filesystem and the time it takes to complete the operation. You can swap out the di command for df or du if that's your thing. The |& redirections the stderr and stdout to the mail command.
How to configure the variables.
FSCKDEV=`grep $TOFSCK /proc/mounts | cut -f1 -d" "`
MAILSUB="weekly file system check $TOFSCK "
Referring to the original post, if you are using $! then that means the process is a child of the current shell, so you can just use `wait $!`. If you are trying to wait for a process created outside of the current shell, then the loop on `kill -0 $PID` is good; although, you can't get the exit status of the process.
If you really _must_ use a loop, this is better than parsing the output of 'ps':
PID=$! ;while kill -0 $PID &>/dev/null; do sleep 1; done
kill -0 $PID returns 0 if the process still exists; otherwise 1
The '[r]' is to avoid grep from grepping itself. (interchange 'r' by the appropriate letter)
Here is an example that I use a lot (as root or halt will not work):
while (ps -ef | grep [w]get); do sleep 10; done; sleep 60; halt
I add the 'sleep 60' command just in case something went wrong; so that I have time to cancel.
Very useful if you are going to bed while downloading something and do not want your computer running all night.
This is a (last resort) way to automate applications that provide no other ways for automation, it would send 'Hello world' to the currently active window. See the manpage (and the -text and -window entries) for how to send special characters and target specific windows.
Using xwininfo, I get the id of my XPlanet background window:
xwininfo: Please select the window about which you
would like information by clicking the
mouse in that window.
xwininfo: Window id: 0x3600001 "Xplanet 1.2.0"
Absolute upper-left X: 0
Now I use xvkbd to tell it to close itself:
xvkbd -xsendevent -window 0x3600001 -text "Q"
Obviously, the best way is to put these commands in a shellscript - just make sure to include a short sleep (sleep .1 should suffice) after each xvkbd call, or some programs will become confused.