Explanation
The backslash character () is used to escape the meaning of the next character in a command line. This means that the next character is treated as a literal character, not as a special character. For example, if you want to use a space in a file name, you can use a backslash before the space to prevent the shell from interpreting it as a separator. Similarly, if you want to split a long command line across multiple lines, you can use a backslash at the end of each line to tell the shell that the command is not finished yet. The shell will ignore the newline character and continue reading the next line as part of the same command.
For example, you can write:
ls -l/home/user/Documents
instead of:
ls -l /home/user/Documents
Both commands will produce the same output, but the first one is easier to read and type. References:
* Linux Essentials - Linux Professional Institute (LPI), section 2.1.2
* 2.1 Command Line Basics - Linux Professional Institute Certification Programs, slide 7.