When working with Linux command line, these special characters serve distinct purposes:

gpg --keyserver keyserver.ubuntu.com --recv 26C2E075 && \\
gpg --export --armor 26C2E075 | sudo apt-key add - && \\
sudo apt-get update

This executes commands sequentially, only proceeding if the previous command succeeds (returns exit status 0):

command1 && command2  # command2 only runs if command1 succeeds

Practical example with error handling:

mkdir new_project && cd new_project || echo "Failed to create directory"

This allows breaking long commands into multiple lines for better readability:

echo "This is a very long string that would make the command " \\
     "hard to read if written on a single line"

Many commands use this to indicate stdin when a filename would normally be expected:

tar -xzvf archive.tar.gz -C /target/directory -  # - reads from stdin

The original example combines all three concepts:

1. First command retrieves GPG key (&& ensures chain continues only if successful)
2. Second command exports and adds the key (using - to read from pipe)
3. Backslashes allow readable line breaks in the script
4. Final apt-get update only runs if all previous steps succeed

These can be combined with other Bash features:

# Complex example combining &&, || and line continuation
[ -f config.file ] && \\
  echo "Config found" || \\
  { echo "Missing config" && exit 1; }

Remember that backslashes must be the very last character on the line - no trailing spaces allowed.

When working with Linux command-line operations, three special characters frequently appear in advanced commands: &&, \\, and -. Let's break down their technical purposes with concrete examples.

The && operator creates conditional command execution - the second command only runs if the first succeeds (returns exit status 0). This is crucial for error handling in scripts:

make configure && ./configure
# ./configure only runs if make succeeds

The backslash at line end (\\) allows breaking long commands into multiple lines for readability. The shell treats subsequent lines as a single command:

echo "This is a very long string that would be hard to \
read if it were all on one line but now it's much \
more manageable"

The hyphen (-) often represents STDIN when a command expects file input. In our original example with apt-key add -, it tells the command to read from pipe input instead of a file:

gpg --export --armor KEYID | sudo apt-key add -
# The exported key is piped to apt-key via STDIN

Here's a more complex real-world example combining all three elements for secure package installation:

wget -qO- https://example.com/setup.sh | bash -s -- \
    --install-dir=/opt/newapp \
    --skip-license \
    && systemctl daemon-reload \
    && systemctl enable newapp

• Always quote arguments when using line continuation
• Consider set -e for better error handling with && chains
• For complex operations, a script might be cleaner than long chained commands