How To Use Cat Command To Append Data To a File on Linux/Unix

To use the cat command to append data to a file on Linux or Unix, you can use the >> operator.

For example, to append the contents of the file input.txt to the end of the file output.txt, you can use the following command:

cat input.txt >> output.txt

This will append the contents of input.txt to the end of output.txt, preserving the existing content of output.txt.

You can also use the cat command to append multiple files to a single file. For example, to append the contents of the files input1.txt, input2.txt, and input3.txt to the end of the file output.txt, you can use the following command:

cat input1.txt input2.txt input3.txt >> output.txt

This will append the contents of the three input files to the end of output.txt, in the order they are specified.

Keep in mind that the >> operator will create the file output.txt if it does not already exist. If the file output.txt already exists, the >> operator will append the new data to the end of the file, preserving the existing content.

If you want to overwrite the existing content of the file output.txt with the new data, you can use the > operator instead of the >> operator.

For example:

cat input.txt > output.txt

This will overwrite the contents of output.txt with the contents of input.txt.

Note: The cat command is often used to display the contents of a file on the linux .