[Linux] Bash tee Uso: Redirect output to files and display it

Overview

The tee command in Bash is used to read from standard input and write to standard output and one or more files simultaneously. This allows you to view the output of a command while also saving it to a file.

Usage

The basic syntax of the tee command is as follows:

tee [options] [arguments]

Common Options

• -a, --append: Append the output to the given files instead of overwriting them.
• -i, --ignore-interrupts: Ignore interrupt signals.
• --help: Display help information about the command.
• --version: Show the version information of the command.

Common Examples

1. Basic Usage: Redirect output to a file while displaying it.

   echo "Hello, World!" | tee output.txt
   

2. Appending to a File: Append output to an existing file.

   echo "Another line" | tee -a output.txt
   

3. Multiple Files: Write output to multiple files.

   echo "Logging data" | tee file1.txt file2.txt
   

4. Using with Other Commands: Combine tee with other commands in a pipeline.

   ls -l | tee directory_listing.txt | grep ".txt"
   

5. Ignoring Interrupts: Use the ignore interrupts option.

   echo "This will not be interrupted" | tee -i output.txt
   

Tips

• Use the -a option when you want to keep adding data to a file without losing the existing content.
• Combine tee with other commands in a pipeline to capture intermediate output for debugging or logging purposes.
• Remember that tee will overwrite files by default, so use the -a option if you want to append instead.