Bash Terminal Redirect to another Terminal

Introduction

The Bash terminal is a powerful tool for interacting with a computer's operating system. One of essential features of Bash is ability to redirect output from one terminal to another. This can be useful in many situations, such as when you want to monitor output of a command in real-time or when you need to send output to another user's terminal. In this article, we will explore how to redirect Bash terminal output to another terminal, including various use cases and examples.

Understanding Bash Terminal Redirection

Bash terminal redirection allows you to redirect output of a command or script to a file or another terminal window. This can be done using several symbols, including ">", ">>", "|", and "2>" symbols. Each symbol has a different meaning, as we will see below.

The ">" symbol is used to redirect output from a command to a file. For example, if you run command "ls > file.txt", output of "ls" command will be redirected to a file called "file.txt" instead of being displayed in terminal.

The ">>" symbol is similar to ">" symbol, but it appends output of a command to a file rather than overwriting it. For example, if you run command "echo "Hello" >> file.txt", text "Hello" will be added to end of "file.txt" file.

The "|" symbol is used to redirect output of one command to another command. For example, if you run command "ls | grep "txt"", output of "ls" command will be piped to "grep" command, which will search for files with ".txt" extension.

The "2>" symbol is used to redirect error output to a file. For example, if you run command "ls /xyz 2> error.txt", any errors generated by "ls" command will be redirected to a file called "error.txt" instead of being displayed in terminal.

Redirecting Output to Another Terminal

Redirecting output to another terminal is a more advanced use case that can be useful in certain situations. To redirect output to another terminal, you will need to use "tty" command to find device file for terminal you want to redirect output to.

The device file for a terminal is usually located in "/dev" directory and has a name that starts with "tty". For example, device file for first terminal on a Linux system is usually "/dev/tty1". To redirect output to another terminal, you can use ">" symbol followed by device file of target terminal.

For example, if you want to redirect output of "ls" command to second terminal on your system, you can use following command −

ls > /dev/tty2

This will send output of "ls" command to second terminal, where it will be displayed instead of in current terminal.

Another use case for redirecting output to another terminal is when you want to send a message to another user's terminal. To do this, you can use "write" command followed by target user's username and device file for their terminal.

For example, if you want to send a message to user "bob" on second terminal of your system, you can use following command −

write bob /dev/tty2

This will open a new terminal window and allow you to send a message to Bob's terminal.

Another use case for redirecting output to another terminal is when you want to run a command on a remote server and view output on your local machine. This is commonly done using SSH protocol, which allows you to securely connect to a remote server and run commands as if you were on server itself.

To redirect output from a remote server to your local machine, you can use SSH command with "-t" option, which allocates a pseudo-tty for remote command. This allows you to view output of remote command in your local terminal window.

For example, if you want to run "ls" command on a remote server and view output on your local machine, you can use following command −

ssh -t user@remote-server "ls"

This will connect to "remote-server" as "user" and run "ls" command. output of command will be redirected to your local terminal window, where you can view it.

In addition to examples we covered, there are many other use cases for Bash terminal redirection to another terminal. For instance, you can use this feature to create a shared terminal session with another user, where both of you can see and interact with same output. You can also use it to monitor system logs or perform other system administration tasks.

Overall, Bash terminal is a powerful tool for managing and controlling system output, and redirecting output to another terminal is a useful feature that can help you get most out of it. By learning various redirection symbols and device files, you can take full advantage of this feature and tailor it to your specific needs. Just be sure to use it responsibly and avoid any potential security risks.

Conclusion

Redirecting Bash terminal output to another terminal can be a powerful tool for monitoring and controlling system output. By using appropriate redirection symbols and device files, you can redirect output to files, other commands, or even other users' terminals. While this feature can be useful in many situations, it's important to use it with caution and be mindful of any potential security risks. For example, if you redirect output to another user's terminal, they may be able to see sensitive information or execute commands they shouldn't.