Check These Out
Use GNU/screen as a terminal emulator for anything serial console related.
screen /dev/tty
eg.
screen /dev/ttyS0 9600
MacOSX: http://www.macosxhints.com/article.php?story=20061109133825654
Cheat Sheet: http://www.catonmat.net/blog/screen-terminal-emulator-cheat-sheet/
you could save the code between if and fi to a shell script named smiley.sh with the first argument as and then do a smiley.sh to see if the command succeeded. a bit needless but who cares ;)
GNU grep's perl-compatible regular expression(PCRE).
The coolest way I've found to backup a wordpress mysql database using encryption, and using local variables created directly from the wp-config.php file so that you don't have to type them- which would allow someone sniffing your terminal or viewing your shell history to see your info.
I use a variation of this for my servers that have hundreds of wordpress installs and databases by using a find command for the wp-config.php file and passing that through xargs to my function.
If you want to pull all of the files from a tree that has mixed files and directories containing files, this will link them all into a single directory. Beware of filesystem files-per-directory limits.
It willl popup a message for each new entry in /var/log/messages
found on the notify-send howto page on ubuntuforums.org.
Posted here only because it is one of the favourites of mine.
-R, -r, --recursive
Read all files under each directory, recursively; this is equivalent to the -d recurse option.
Next time you are leaching off of someone else's wifi use this command before you start your bittorrent ...for legitimate files only of course.
It creates a hexidecimal string using md5sum from the first few lines of /dev/urandom and splices it into the proper MAC address format. Then it changes your MAC and resets your wireless (wlan0:0).
Converts any number of seconds into days, hours, minutes and seconds.
sec2dhms() {
declare -i SS="$1"
D=$(( SS / 86400 ))
H=$(( SS % 86400 / 3600 ))
M=$(( SS % 3600 / 60 ))
S=$(( SS % 60 ))
[ "$D" -gt 0 ] && echo -n "${D}:"
[ "$H" -gt 0 ] && printf "%02g:" "$H"
printf "%02g:%02g\n" "$M" "$S"
}