====== Ubuntu - Bash - Scripts - tree ======

**tree** recursively searches in each directory and finds all files, which are then displayed in a hierarchical file tree, thus providing global inspection of files and their nested depth structure.

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===== Usage =====

<code bash>
tree [dir]
</code>

----

Example call:

<code bash>
tree $HOME
</code>

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===== Code =====

<code bash>
#!/bin/bash
#
# @ (#) tree v1.0 Visual display of a file tree 
# output to a file tree structure screen
#

if [ "$#" -gt 1]
then echo "tree: wrong arg count"> & 2
echo "usage: tree [dir]"> & 2
exit 2
fi

if [ "$#" -eq 1]
 then if [! -d $1]
 then echo "$0: $1 not a directory"> & 2
 echo "usage: tree [dir]"> & 2
 exit 2
 fi
fi

find $ {1: -.} -print | sort | sed -e "1p" -e "1d" \
 -e "s | [^ /] * / | / | g" \
 -e "s | [^ * / | / |" \
 -e "s | / \ ([^ /] * \) $ | \ 1 |"
</code>

----

===== Example Usage =====

This uses an implicit directory (the current directory) as the beginning of the file tree.

<code bash>
tree
</code>

----

Print the tree listing for each file of the entire system. 

<code bash>
tree /
</code>

----

This shows the tree-format for all other users system (assuming that all user directories are the same directory, such as /usr/*).

<code bash>
tree $HOME / ..
</code>

----

===== Test =====

Consider the example of a directory structure.  Let the root directory to /tmp with two directories: a and b.  The catalog is a subdirectories
log aa, which contains the file1 file directory and b, respectively, subdirectory bb, containing file file2.  

The **find** command will give a printout like this:

<code bash>
find /tmp -print
</code>

result:

<code>
/tmp
/tmp/a
/tmp/a/aa
/tmp/a/aa/file1
/tmp/b
/tmp/b/bb
/tmp/b/bb/file2
</code>

As can be seen from this listing, the files a and aa are directories and file file1 is located at the bottom of the file tree.  

----

Now compare this result with the results of the **tree** script.

<code bash>
tree /tmp
</code>

result:

<code>
/tmp
/a
//aa
///file1
/b
//bb
///file2
</code>