Bash: How to trim a string or a variable

Sometimes you are looking for a simple way to get rid of leading or tailing spaces in a string or variable. Here’s a function I usually use in my bash scripts:

function trim() {
trvar=$1
trvar="${trvar#"${trvar%%[![:space:]]*}"}"
trvar="${trvar%"${trvar##*[![:space:]]}"}"
echo -n "$trvar"
}

… where the first line is responsible for leading and the second line for trailing spaces.

To delete all spaces in a string, you can use:
# echo " this is an example " | tr -d [[:space:]]