The //**history**// command in Linux and Unix-like systems is a command line utility that displays a list of the previously executed commands in the current shell session. By default, the **history** command will display the commands in the order they were executed, with the most recent commands appearing at the bottom of the list. Each command is preceded by a number, which is the command's history number.

For example, if you run the **history** command in Linux, you might see output similar to this:

<code>
  1  pwd
  2  cd Mail
  3  date
  4  ls -la
  5  history
  </code>
  
This output shows the **history** of commands that have been executed in the current shell session. Each command is preceded by a number, which is the command's history number. You can use the history number to re-execute a command by prefixing it with an exclamation point (!) , for example !3 will execute the 3rd command in the history list, in this case it will be **date**

The output will be slightly different if you execute the history command in FreeBSD. The output will also show the time of execution for each command,

<code>
     1  18:12   man history
     2  18:12   w
     3  18:13   ls -la
     4  18:13   history
     5  18:13   df
     6  18:13   du

</code>

You can also use keywords or patterns to search for a specific command in the **history** list. For example, you can use the **history | [[unix_commands:grep|grep]]** command to find all commands that contain a specific word.

<code>
history | grep "ls"</code>

The **history** command also accepts options to customize the output, for example:

<code>
-c: Clear the history list.
-w: Write the current history list to the history file.
-n: Append the new history lines (those entered since the beginning of the current bash session) to the history file.
-r: Read the history file and append its contents to the current history list.
-p: Perform history substitution on the following args and display the result on the standard output.
-a: Append the new_history list to the history file.</code>


The **history** command is a powerful tool that allows you to easily recall and re-execute previous commands, and it's a great way to keep track of what you've done on the command line and to learn new commands.