Trim a string or variable shell script.

trim.sh

# -----------------------------------------
#  Trim string
#
#  @1 = string
# -----------------------------------------
function trim () {
    local s2 s="$*"
    # note the tab character in the expressions of the following two lines when copying
    until s2="${s#[   ]}"; [ "$s2" = "$s" ]; do s="$s2"; done
    until s2="${s%[   ]}"; [ "$s2" = "$s" ]; do s="$s2"; done
    echo "$s"
}