How to Redirect Output of a Program to a Zip File

1. Overview

In Linux, knowing how to redirect the output of a program to a ZIP file is important. As a system administrator, it allows us to save a program’s output neatly and organized. Also, this approach enables us to compress and archive the output, making it easier to share and manage.

In this tutorial, we’ll explore how to redirect the output of a program to a ZIP file.

2. Understanding the Basics

Before we proceed, let’s take a look at the concepts involved:

• standard output (stdout) – Any program in Linux has the stream standard output. This is where the program prints its normal output, typically the terminal.
• output redirection – In output redirection, we can use the >> or > operators to redirect the program output to a file. The >> operator appends the output to the end of an existing file or creates a new file if it doesn’t exist. Meanwhile, > overwrites the contents of the existing file or creates a new file if it’s absent.
• piping – In piping, we make use of the pipe (|) symbol to enable us to pass the output of one command as the input for another command.
• ZIP compression – ZIP is a common file compression format for reducing the size of files and folders, making it easier to transfer and store them.

In the next section, let’s discuss some approaches that we can use to achieve our goal.

3. Redirecting Output of a Program to a Zip File

To demonstrate, we’ll use a simple program, ls, which simply lists the contents of the current directory.

3.1. Redirecting Output to a Temporary File

Here, we redirect the program output to a temporary file and then compress it:

$ ls > output.txt

In this example, the ls command output redirects to the file output.txt. At this point, we can use the cat command to ensure that this temporary file contains the desired content:

$ cat output.txt
file1.txt
projects
...

Above, the command displays the contents of the output.txt.

Next, let’s compress the temporary file output.txt into a ZIP file:

$ zip -q output.zip output.txt

Above, zip compresses output.txt into an archive named output.zip.

3.2. Piping the Program’s Output to the zip Command

In this next approach, we utilize piping to provide the zip command with a program’s output:

$ ls | zip -q output.zip -

So, let’s explore the above command:

• ls – Lists the files and directories in the current directory.
• | – Redirects the output of the ls command on its left as the input of the zip command on its right.
• zip – This command compresses files and directories to a zip archive.
• -q – Instructs the zip command not to show unnecessary output during compression unless it’s an error.
• output.zip – Represents the name of the zip file to be created.
• – – Represents the source of the input. In this case, it declares that the input for the zip command comes from the standard input. This input is the output of the ls -l command.

The command above generates the current directory contents and then compresses them, creating output.zip.

3.3. Combining tee With the zip Command

This combination of the tee and zip commands allows us to simultaneously show the ls program’s output in the terminal while creating a ZIP file containing this output in the background. To clarify, the details on the ongoing ZIP file creation process are not visible:

$ ls | tee >(cat > ls_output.txt) && zip output.zip ls_output.txt && rm ls_output.txt
file1.txt
projects
...

Let’s break down the above command:

• ls – Lists the contents of the current directory.​
• tee – Ensures that the output from the ls command is sent to standard output in the terminal and also to a process substitution.
• >(cat > ls_output.txt) – In the process substitution, the output of the ls command is written to a file named ls_output.txt. It creates the file if it doesn’t exist.
• && – This logical AND operator in Bash executes the command on its right only if the command on its left succeeds.
• zip output.zip ls_output.txt – Zips the ls_output.txt file into a ZIP archive named output.zip.
• rm ls_output.txt – Deleted the ls_output.txt file created in the current directory.

So, the command above creates the ZIP archive outzip.zip. Now, let’s use the unzip command to inspect the contents of this zip archive:

$ unzip -l output.zip
Archive:  output.zip
  Length      Date    Time    Name
---------  ---------- -----   ----
     1358  2023-03-18 04:00   file1.txt
        0  2023-12-18 12:12   projects/
      ...

Let’s have a look at this command:

• unzip – This command extracts files from zip archives.
• -l – This list option instructs unzip to show information on the contents of the archive without extracting them. This information includes file size, date of modification, and other details.

From this output, we can see that output.zip contains the output of the ls command.

4. Conclusion

In this article, we explored how to redirect the output of a program and also use the zip command to compress data. In detail, we discussed piping program output directly to the zip command, redirecting this output to a temporary file, and utilizing the tee command. These approaches are straightforward to implement. Therefore, we can choose either based on preference.