Use the -p option to mkdir and make all parent directories along with their children in a single command.

mkdir -p tmp/a/b/c

Save time when making multiple files or directories (or performing any command requiring a list) where the file names only slightly differ.

$ ls
$ touch tst{1,2,3,4,5}.txt
$ ls
tst1.txt        tst2.txt        tst3.txt        tst4.txt        tst5.txt
$ mkdir dir{1,2,3}
$ ls
dir1       dir2       dir3       tst1.txt   tst2.txt   tst3.txt   tst4.txt   tst5.txt

The following command creates in the /usr/project directory, a copy of the current working directory structure:

find . -type d -print|sed 's@^\.\{0,1\}@/usr/project@' | sed 's/ /\\ /' | xargs mkdir -p

Seen on http://www.splitbrain.org/blog/2008-02/27-keeping_your_home_directory_organized

Having one temporary directory for downloads etc can quickly become a mess, so try this tip to organise by date. Put this into your .bashrc

export TD="$HOME/temp/`date +'%Y-%m-%d'`"

td(){

    td=$TD

    if [ ! -z "$1" ]; then

        td="$HOME/temp/`date -d "$1 days" +'%Y-%m-%d'`";

    fi

    mkdir -p $td; cd $td

    unset td

}

You'll receive a new function 'td' for making temp-dirs under $HOME/temp/ named by date. It is also possible to switch days back with 'td -[n]', i. e. 'td -3' which means '3 days back from now'.