Commands by dooblem

Outputs the number of different pixels.

2 params to increase tolerance:

* thumbnails size

* fuzz, the color distance tolerance

See http://en.positon.org/post/Compare-/-diff-between-two-images for more details.

This is what we use.

You can grep -v 127.0.0.1 if you wish.

with zcat force option it's even simpler.

Listens for events in the directory. Each created file is displayed on stdout. Then each fileline is read by the loop and a command is run.

This can be used to force permissions in a directory, as an alternative for umask.

More details:

http://en.positon.org/post/A-solution-to-the-umask-problem%3A-inotify-to-force-permissions

shuf is in the coreutils package

Another one.

Maybe not the quicker because of the sort command, but it will also look in other man sections.

updated with goodevilgenius 'shuf' idea

The pee command is in the moreutils package.

Do the same as pssh, just in shell syntax.

Put your hosts in hostlist, one per line.

Command outputs are gathered in output and error directories.

Just a little simplification.

I just wanted a simple DNS request.

Because host and nslookup commands are not on all systems, we use getent instead.

Thanks aulem for that tip.

This is /bin/sh compatible.

Using just globing

'data' is the directory to backup, 'backup' is directory to store snapshots.

Backup files on a regular basis using hard links. Very efficient, quick. Backup data is directly available.

Same as explained here :

http://blog.interlinked.org/tutorials/rsync_time_machine.html

in one line.

Using du to check the size of your backups, the first backup counts for all the space, and other backups only files that have changed.

I use zgrep because it also parses non gzip files.

With ls -tr, we parse logs in time order.

Greping the empty string just concatenates all logs, but you can also grep an IP, an URL...

Works with files containing spaces and for very large directories.

Open a file directly with execution permission.

Put the function in your .bashrc

You can also put this in your vimrc:

and open a new file like this:

Another way of counting the line output of tail over 10s not requiring pv.

Cut to have the average per second rate :

tail -n0 -f access.log>/tmp/tmp.log & sleep 10; kill $! ; wc -l /tmp/tmp.log | cut -c-2

You can also enclose it in a loop and send stderr to /dev/null :

while true; do tail -n0 -f access.log>/tmp/tmp.log & sleep 2; kill $! ; wc -l /tmp/tmp.log | cut -c-2; done 2>/dev/null

Displays the realtime line output rate of a logfile.

-l tels pv to count lines

-i to refresh every 10 seconds

-l option is not in old versions of pv. If the remote system has an old pv version:

ssh tail -f /var/log/apache2/access.log | pv -l -i10 -r >/dev/null

or "Execute a command with a timeout"

Run a command in background, sleep 10 seconds, kill it.

You can test it with:

find /& sleep10; kill $!

Reports all local partitions having more than 90% usage.

Just add it in a crontab and you'll get a mail when a disk is full.

(sending mail to the root user must work for that)

Very handy if you have done a package selection mistake in aptitude.

Note that it's better to do a Ctrl+U (undo) in aptitude if possible, because the keep-all will clear some package states (like the 'hold' state).

Instead of opening your browser, googling "whatismyip"...

Also useful for scripts.

dig can be found in the dnsutils package.