How to trim whitespace from a Bash variable?

Question

I have a shell script with this code:

var=`hg st -R \"$path\"`
if [ -n \"$var\" ]; then
    echo $var
fi

But the conditional code always ex

Answer 1

In order to remove all the spaces from the beginning and the end of a string (including end of line characters):

echo $variable | xargs echo -n

This will remove duplicate spaces also:

echo "  this string has a lot       of spaces " | xargs echo -n

Produces: 'this string has a lot of spaces'