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How To Determine Uncompressed Size of a Zip File Without Decompressing

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In this article, we will delve into the process of determining the uncompressed size of a zip file without decompressing it. This can be a handy trick when you want to know how much space you need to allocate for unzipping a file, or when you’re simply curious about the size of the uncompressed data. We’ll be using the command-line interface (CLI) for this task, as it provides the most direct and versatile approach.

Quick Answer

To determine the uncompressed size of a zip file without decompressing it, you can use the unzip -l command in the command-line interface (CLI). The final line of the output will display the total decompressed size in bytes.

The ‘unzip -l’ Command

The primary tool we’ll be using is the unzip command with the -l flag. The unzip command is used to list, test, or extract compressed files from a ZIP archive. The -l flag specifically instructs unzip to list the contents of the ZIP file.

Here’s the basic syntax:

unzip -l yourzipfile.zip

This command will provide a listing of every file in the zip along with its size in bytes. The final line of the output will display the total decompressed size in bytes.

Refining the Output

If the zip file contains a large number of files, the output can be quite long. To prevent this, you can use the tail command, which displays the last part of files. For example:

unzip -l yourzipfile.zip | tail -n 15

The -n flag followed by a number specifies the number of lines at the end of the files to display. In the above example, it will show the last 15 lines of the output.

Retrieving the Size in Bytes

To directly retrieve the size in bytes, you can use the following command:

unzip -l yourzipfile.zip | tail -1 | xargs | cut -d' ' -f1

Here, tail -1 fetches the last line of the output, xargs converts the input into arguments for the next command, and cut -d' ' -f1 splits the input into fields based on spaces and selects the first field, which is the size in bytes.

Converting the Size to Megabytes

If you prefer to see the size in megabytes, you can use bc to perform the conversion:

bc<<<"$(unzip -l yourzipfile.zip | tail -1 | xargs | cut -d' ' -f1)/1000/1000"

bc is a language that supports arbitrary precision numbers and allows you to perform mathematical operations.

Formatting the Output

For a nicely formatted number, you can use the numfmt command:

unzip -l yourzipfile.zip | tail -1 | xargs | cut -d' ' -f1 | numfmt --to=iec-i --suffix=B

The numfmt command converts numbers between human-readable and computer-readable formats. The --to=iec-i flag specifies the output format, and --suffix=B appends ‘B’ to the output to indicate bytes.

Conclusion

In this article, we’ve covered how to determine the uncompressed size of a zip file without decompressing it. By using the unzip command with the -l flag and a series of other commands to refine and format the output, you can easily find out the uncompressed size of a zip file. Remember to replace ‘yourzipfile.zip’ with the name of your actual zip file when using these commands.

Can I determine the uncompressed size of a zip file without decompressing it?

Yes, you can determine the uncompressed size of a zip file without decompressing it by using the unzip -l command in the command-line interface (CLI).

What does the `-l` flag do in the `unzip` command?

The -l flag in the unzip command is used to list the contents of a zip file without extracting them. It provides a listing of every file in the zip along with their sizes.

How can I prevent the `unzip -l` command from displaying a long output when the zip file contains a large number of files?

To prevent a long output, you can use the tail command along with the unzip -l command. For example, unzip -l yourzipfile.zip | tail -n 15 will display the last 15 lines of the output.

How can I retrieve the size of the uncompressed file in bytes?

To directly retrieve the size in bytes, you can use the command unzip -l yourzipfile.zip | tail -1 | xargs | cut -d' ' -f1. It fetches the last line of the output, splits it into fields based on spaces, and selects the first field, which is the size in bytes.

Can I convert the size in bytes to megabytes?

Yes, you can convert the size in bytes to megabytes by using the bc command. For example, bc<<<"$(unzip -l yourzipfile.zip | tail -1 | xargs | cut -d' ' -f1)/1000/1000" will give you the size in megabytes.

How can I format the output to have a nicely formatted number?

To have a nicely formatted number, you can use the numfmt command. For example, unzip -l yourzipfile.zip | tail -1 | xargs | cut -d' ' -f1 | numfmt --to=iec-i --suffix=B will format the output in a human-readable format with the ‘B’ suffix to indicate bytes.

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