commandlinefu.com is the place to record those command-line gems that you return to again and again.
Delete that bloated snippets file you've been using and share your personal repository with the world. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.
If you have a new feature suggestion or find a bug, please get in touch via http://commandlinefu.uservoice.com/
You can sign-in using OpenID credentials, or register a traditional username and password.
First-time OpenID users will be automatically assigned a username which can be changed after signing in.
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.
» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10
Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):
Subscribe to the feed for:
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.
TOFSCK=/path/to/mount
FSCKDEV=/dev/path/device
or
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.
An example:
Using xwininfo, I get the id of my XPlanet background window:
alanceil@kvirasim:19:51:0:~> xwininfo
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
(..etc..)
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.