This is just my own little notepad for jotting down stuff. Perhaps it will be helpful to you
too.

Shell Scripting:

For loops:

for file in `ls`
do
mv $file $file.copy
done

For loops with limited iterations:

i=0
for file in `ls`
do
let i=i+1
if [ $i -gt 10 ]
then
mv $file.copy
fi

If loops in bash:

if [ 1 = 1 ] ; then echo "yes" ; else echo "no" ; fi

Testing for existance of two command line arguments...

if ( ! [ $1 ] || [ ! $2 ] ) ; then echo "yup" ; else echo "nope" ; fi
(and yeah, you could just test for $2, but part of the purpose here is to
demonstrate boolean operators in if statements...)

identd in Mac OS X - in /etc/inetd.con  (comment out the other similiar line)

auth stream tcp wait root /usr/libexec/tcpd identd -w -t120


Kill all processes with 'foo' in the name.

kill -9 `ps aux | grep foo | grep -v grep | awk '{print $2}'`

Terminal transparency in Mac OS X: from a shell, execute:
defaults write com.apple.Terminal TerminalOpaqueness 0.8

ansi color escape sequences in bash and how to type them! (I am the only person in the world
that offers this information):

(stand by)

To tar a directory:

tar  -cvf file.tar directory

To enable a chroot'd ftp access only account in linux with proftpd:

in /etc/proftpd.conf, put the following line:
DefaultRoot /home/guest guest

...where guest is the account name of the user, and /home/guest is the path to the dir you want him chroot'd to
(his home directory makes a fine choice)

Then as root:
csch guest

...then enter
/bin/deny


To provide host-allow protection on an URL (regex savy), into the main config file
for apache 1.3 or later, append the following lines:

<LocationMatch "*/~andre/bits/webcam_archives/*.jpg">
Order Deny,Allow
Deny from all
Allow from .tribal.org
Allow from .blackmagiclabs.com
Allow from .blackmagiclabs.org
Allow from .blackmagiclabs.net
</LocationMatch>


To get Mac OSX's lookupd to consult /etc/hosts before the netinfo db:

as root:
niutil -create . /locations/lookupd/hosts [hit enter]
niutil -createprop . /locations/lookupd/hosts LookupOrder FFAgent DNSAgent
[hit enter]