Make directories

% mkdir <directory name>:  used to create a new directory.
Example:
jp@ubuntu:~/demo$ mkdir dir1
jp@ubuntu:~/demo$ ls
dir1

% mkdir -p <dir name>: Creates all directories leading up to the given directory that do not exist previously.  No error if existing.
Example:
jp@ubuntu:~/demo$ pwd
/home/jp/demo
jp@ubuntu:~/demo$ ls
dir1
jp@ubuntu:~/demo$ mkdir -p dir2/sub1/sub2/
jp@ubuntu:~/demo$ ls
dir1  dir2
jp@ubuntu:~/demo$ ls -R
.:
dir1  dir2
./dir1:
./dir2:
sub1
./dir2/sub1:
sub2
./dir2/sub1/sub2:

% mkdir -v <dir name>:  Creates  directory and prints message for each created directory.
Example:
jp@ubuntu:~/demo$ ls
dir1  dir2
jp@ubuntu:~/demo$ mkdir -v dir3
mkdir: created directory `dir3'
jp@ubuntu:~/demo$ ls
dir1  dir2  dir3

% mkdir -m <dir name>: Creates directory and sets file mode(as in chmod).
Example:
jp@ubuntu:~/demo$ ls -l
total 12
drwxr-xr-x 2 jp jp 4096 2011-10-05 23:14 dir1
drwxr-xr-x 3 jp jp 4096 2011-10-05 23:21 dir2
drwxr-xr-x 2 jp jp 4096 2011-10-05 23:26 dir3
jp@ubuntu:~/demo$ mkdir -m 0007 dir4
jp@ubuntu:~/demo$ ls
dir1  dir2  dir3  dir4
jp@ubuntu:~/demo$ ls -l
total 16
drwxr-xr-x 2 jp jp 4096 2011-10-05 23:14 dir1
drwxr-xr-x 3 jp jp 4096 2011-10-05 23:21 dir2
drwxr-xr-x 2 jp jp 4096 2011-10-05 23:26 dir3
d------rwx 2 jp jp 4096 2011-10-05 23:29 dir4
jp@ubuntu:~/demo$ ls dir4
ls: cannot open directory dir4: Permission denied
Only others (has read, write and execute permission) can access the directory "dir4".  Owner and user cannot access it, since the chmod for them is set to zero.