Linux Error Redirection

What is the difference between > and >>?

The > operator overwrites the contents of the file if it already exists, while >> appends the output to the end of the file.

Example:

echo "Line 1" > file.txt    # Overwrites file.txt with "Line 1"
echo "Line 2" >> file.txt   # Appends "Line 2" to file.txt

How can I redirect both standard output and standard error to different files?

You can use the following syntax to redirect standard output and standard error to separate files:

command > output.txt 2> error.txt

This command will redirect standard output to output.txt and standard error to error.txt.

Can I redirect the output of multiple commands to the same file?

Yes, you can use the following syntax to redirect the output of multiple commands to the same file:

command1 >> output.txt; command2 >> output.txt; command3 >> output.txt

This will append the output of command1, command2, and command3 to the output.txt file.

How can I discard the output or error messages of a command?

To discard the output or error messages of a command, you can redirect them to the /dev/null device, which is a special file that discards all data written to it.

Example:

command > /dev/null   # Discards standard output
command 2> /dev/null  # Discards standard error

What is the purpose of the &> operator?

The &> operator is a shorthand for redirecting both standard output and standard error to the same file or stream. It is equivalent to the >file 2>&1 syntax.

Example:

command &> output.txt  # Redirects both stdout and stderr to output.txt

Note that the &> operator is not supported in all shells, such as sh and ksh. It works in bash and zsh.

Redirection is a feature in Linux which can be used to change the standard input device (keyboard) or standard output device (screen) during the execution of a command. The basic process of any Linux command is that it takes an input and gives output but the standard/input and output can be changed using the redirection technique.