View source for Linux dirs stack - pushd and popd

<code>pushd</code>, <code>popd</code>, and <code>dirs </code>are shell builtins which allow you manipulate the [http://www.gnu.org/software/bash/manual/html_node/The-Directory-Stack.html#The-Directory-Stack directory stack]. This can be used to change directories but return to the directory from which you came.


The directory stack is a list of recently-visited directories. 
*<code>pushd</code> add directory to the stack as it changes the current directory, and 
*<code>popd</code> removes specified directories from the stack and changes the current directory to the directory removed. 
*<code>dirs</code> displays the contents of the directory stack. The current directory is always the "top" of the directory stack.

The contents of the directory stack are also visible as the value of the <code>DIRSTACK</code> shell variable. 


FILO first-in-dir last-out-dir flow
<source lang="bash">
pushd navigate/ #cd to navigate/ dir and adds absolute path to navigate/ dir to directory stack
dirs -v         #manages dir stack, -v lists the stack verbosely
popd            #consumes first pushed/added directory from stack
</source>


Demonstrate
<source lang="bash">
mkdir -p ./navigate/dir{1..3}
piotr@ubuntu /tmp $ pushd navigate/              #cd and added to left/top of the stack
/tmp/navigate /tmp
piotr@ubuntu /tmp/navigate $ pushd dir1/         #cd and added to left/top of the stack
/tmp/navigate/dir1 /tmp/navigate /tmp
piotr@ubuntu /tmp/navigate/dir1 $ pushd ../dir2/ #cd and added to left/top of the stack
/tmp/navigate/dir2 /tmp/navigate/dir1 /tmp/navigate /tmp 
piotr@ubuntu /tmp/navigate/dir2 $ pushd ../dir3/ #cd and added to left/top of the stack
/tmp/navigate/dir3 /tmp/navigate/dir2 /tmp/navigate/dir1 /tmp/navigate /tmp
piotr@ubuntu /tmp/navigate/dir3 $ dirs -v        #show the directory stack
 0  /tmp/navigate/dir3
 1  /tmp/navigate/dir2
 2  /tmp/navigate/dir1
 3  /tmp/navigate
 4  /tmp
piotr@ubuntu /tmp/navigate/dir3 $ popd           #cd to last added /or left /or with the index [1]
/tmp/navigate/dir2 /tmp/navigate/dir1 /tmp/navigate /tmp
piotr@ubuntu /tmp/navigate/dir2 $ popd
/tmp/navigate/dir1 /tmp/navigate /tmp
piotr@ubuntu /tmp/navigate/dir1 $ popd
/tmp/navigate /tmp
piotr@ubuntu /tmp/navigate $ popd
/tmp
piotr@ubuntu /tmp $ popd
bash: popd: directory stack empty
</source>


Navigate using <code>cd</code>, it does not remove a dir from the stack. <code>cd</code> takes advantage using directory stack, here cd to <tt>index.2</tt> dir in the stack, just remember <tt>index.0</tt> always changes, to preserve the order always pushd dummy dir /or current dir.
<source lang=bash>
dirs -v
 0  /tmp/navigate/dir2
 1  /tmp/navigate/dir3
 2  /tmp/navigate
 3  /tmp
cd ~2   #will cd -> /tmp/navigate, not removing the directory entry on the stack
</source>


Additional options and switches
<source lang="bash">
dirs -c #clears out the directory stack
</source>