mktemp_d makes a temporary directory and prints the path of it.

mktemp_d.sh

#! /bin/sh

# Wraps "mktemp -d $1XXXXXXXXXX"
mktemp_d() {(
  umask 077
  {
    # Use mktemp if available.
    dir=`mktemp -d "$1XXXXXXXXXX" 2>/dev/null` && [ -d "$dir" ]
  } || {
    # Fall back on mkdir.
    dir=
    i=0
    while [ $i -lt 100 ]; do
      next_dir=$1$$$i$RANDOM$RANDOM
      if mkdir "$next_dir" >/dev/null 2>&1; then
        dir=$next_dir
        break
      fi
      i=`expr $i + 1`
    done
    [ "x$dir" != x ] && [ -d "$dir" ]
  } || {
    echo "mktemp_d: failed to create a temporary directory" >&2
    exit 1
  }
  echo "$dir"
)}

# Typical use.

tmpdir=`mktemp_d "${TMPDIR:-/tmp}/tmp"`
trap 'rm -rf "$tmpdir"' 0 1 2 13 15
# Do something on files created in the temporary directory here.
touch "$tmpdir/tmp1"