It sometimes comes up that the usual trick of reading in a stream with a pipe and a while loop doesn't work, since the pipe causes a subshell and any variables set in the subshell are unavailable to the parent.
For example the normal trick (output the first few lines of the /etc/services file, just the first two columns and not empty or comment lines):

[uphill@zagreb]: grep -v ^# /etc/services | grep -v ^$ | head | awk '{print $1" "$2;}'
tcpmux 1/tcp
tcpmux 1/udp
rje 5/tcp
rje 5/udp
echo 7/tcp
echo 7/udp
discard 9/tcp


Sometimes it's easier to write a quick script in bash that uses arrays rather than figure out how to do it with something more appropriate like awk or perl.

It's really very quick and simple. To start, declare your variable as an array


[uphill@host]: declare -a myvar


If the array is going to be global then add x to export it.


[uphill@host]: declare -ax myvar


Then you can put things into your array like this:

Sleeping

I sometimes have to transfer files with spaces in the names, I like using a for loop, but the usual way doesn't work.

Usual way:

for file in `find . -type f|grep .ext$` do /do/something/to $file done

To get around this I use a while loop with a read instead. Using the read will read to the end of the line, enclosing within quotes escapes the spaces.

Unusual way: