In PHP, the backtick character (`) is used to enclose a string that should be interpreted as a command by the shell. This is known as shell expansion.
For example, you can use the backtick operator to execute a shell command and store the output in a variable:
$output = `ls -l`;
echo $output;This will execute the ls command and store the output in the $output variable.
The backtick operator is also sometimes called the “backquote” or “backticks” operator.
It is important to note that the backtick operator is different from the single quote (‘) and double quote (“) operators, which are used to define string literals in PHP. The single quote and double quote operators do not interpret special characters or escape sequences, while the backtick operator does.
Here’s an example of the difference between the single quote and backtick operators:
$name = 'John';
echo 'Hello $name'; // Outputs: Hello $name
echo "Hello $name"; // Outputs: Hello John
echo `echo Hello $name`; // Outputs: Hello John
