Ubuntu – What does the second column in the output of ‘ls -n’ mean

From man bash (somewhere after the line 3813):

!      Start  a  history substitution, except when followed by a blank,
          newline, carriage return, = or ( (when the extglob shell  option
          is enabled using the shopt builtin).

[...]

$      The  last  word.   This  is  usually the last argument, but will
          expand to the zeroth word if there is only one word in the line.

So, the !$ will recall the last argument from the last command from history.

Here are some examples and equivalents:

$ echo foo bar
foo bar
$ echo !$ # recall the last argument from the last command from history
echo bar
bar

$ echo foo bar
foo bar
$ echo !:$ # the same like `!$'
echo bar
bar

$ echo foo bar
foo bar
$ echo !:2  # recall the second (in this case the last) argument from the last command from history
echo bar
bar

$ echo foo bar
foo bar
$ echo $_ # gives the last argument from the last command from history
bar

$ echo foo bar
foo bar
$ echo Alt+. # pressing Alt and . (dot) in the same time will automatically insert the last argument from the last command from history
bar

$ echo foo bar
foo bar
$ echo Alt+_ # the same like when you press Alt+.
bar

$ echo foo bar
foo bar
$ echo Esc. # the same like when you press Alt+.
bar

All of these will work only inside of an interactive shell. But if you use that command from your question inside of a script as you said that you sow it, then the things are different: when you run the script, this will start in a new shell, a non-interactive shell, so the history expansion doesn't has any effect in this case and so the command:

echo "An Example" > !$

creates the file !$ if not present (otherwise overwrites it) and write An Example into it.

The ls -al command is a combination of ls -l (use a long listing format) and ls -a (do not ignore entries starting with .)

The result is a long list (the ls -l part) with (from left to right):

• filetype
• file permissions
• number of links
• owner name
• owner group
• file size
• time of last modification
• the name of the file or directory

while the ls -a means that hidden files are listed as well.

see also man ls (as always man is the first source of information), and this link.

A little more explanation on what you see

The output starts with the number of disc blocks, used by the directory (in your case 76). From the GNU docs:

For each directory that is listed, preface the files with a line ‘total blocks’, where blocks is the total disk allocation for all files in that directory. The block size currently defaults to 1024 bytes, but this can be overridden.

Then:

• the first character describes wether it is a directory (d) or a file (-) (or some other file type, see the docs for a complete listing)

File permissions:

• the permissions in a nine-character section (3x3 for owner / group / other users)

Links

• The number of links is the number of hard links to the file. For a directory, the number of hard links is the number of (immediate) subdirectories plus the parent directory and itself.

Owner

• name of the owner
• name of the (owner) group

File size

• You see many files with the size of 4096, which is the minimum size for a directory on ext3 and ext4.