Linux shell prompt
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ZIP files are a universal archive commonly used on Windows, macOS, and even Linux systems. You can create a zip archive or unzip files from one with some common Linux terminal commands.

The ZIP Compressed Archive File Format

Thanks to the dominance of the ZIP format in the Windows realm, ZIP files are probably the most common form of compressed archive in the world.

While .tar.gz and tar.bz2 files are common on Linux, Windows users will probably send you an archive in ZIP format. And, if you want to archive some files and send them to a Windows user, the ZIP format will be the easiest, most compatible solution for everyone.

RELATED: How to Extract Files From a .tar.gz or .tar.bz2 File on Linux

zip, unzip, and Other Utilities

You may already know that Linux and Unix-like operating systems such as macOS have tools to allow you to create ZIP files and extract files from them, called zip and unzip. But there’s a whole family of related utilities such as zipcloak, zipdetails, zipsplit , and zipinfo.

We checked some Linux distributions to see whether they included these utilities in the standard installation. All of the utilities were present in Ubuntu 19.04, 18.10, and 18.04. They were also present in Manjaro 18.04. Fedora 29 included zip and unzip, but none of the other utilities and that was also the case for CentOS.

To install the missing elements on Fedora 29, use the following command:

sudo dnf install perl-IO-Compress

zip installation command for Fedora

To install the missing elements on CentOS 7, use the following command:

sudo yum install perl-IO-Compress

Zip install command in Centos

If any of the zip utilities are missing from a Linux distribution that wasn’t mentioned above, use that Linux distribution’s package management tool to install the required package.

How to Create a ZIP File with the zip Command

To create a ZIP file, you need to tell zip the name of the archive file and which files to include in it. You don’t need to add the “.zip” extension to the archive name, but it does no harm if you do.

To create a file called source_code.zip containing all the C source code files and header files in the current directory, you would use this command:

zip source_code *.c *.h

zip command in a terminal window

Each file is listed as it’s added. The name of the file and the amount of compression that was achieved on that file is shown.

output from zip command in a terminal window

If you look at the new ZIP archive, you can see that the “.zip” file extension has been added automatically by zip.

ls -l source_code.zip

ls on zip archive in a terminal window

If you do not want to see the output from zip as the ZIP file is created, use the -q (quiet) option.

zip -q source_code *.c *.h

-q quiet option in a terminal window

Including Directories in ZIP Files

To include sub-directories in the ZIP file, use the -r (recursive) option and include the name of the sub-directory on the command line. To create a ZIP file as before and also include the archive sub-directory, use this command.

zip -r -q source_code archive/ *.c *.h

-r recursive option in a terminal window

To be considerate to the person who will be extracting the files from the ZIP file you’re creating, it is often polite to create ZIP files with the files inside it contained in a directory. When the person who receives the ZIP file extracts it, all of the files are placed neatly within a directory on their computer.

In the following command, we’re going to archive the work directory and all sub-directories. Note that this command is being issued from the parent directory of the work folder.

zip -r -q source_code work/

zipping the work directory in a terminal window

Setting the Level of Compression

You can set how much compression is applied to the files as they are added to the ZIP archive. The range is from 0 to 9, with 0 being no compression at all. The higher the compression, the longer it takes to create the ZIP file. For modestly sized ZIP files, the time difference isn’t a significant penalty. But then, for modestly sized ZIP files, the default compression (level 6) is probably good enough anyway.

To get zip to use a specific level of compression, pass the number as an option on the command line, with a “-“, like this:

zip -0 -r -q source_code work/

-0 compression option in a terminal window

The default compression level is 6. There is no need to provide the -6 option, but it will do no harm if you do.

zip -r -q source_code work/

level 6 compression in a terminal window

The maximum compression level is level 9.

zip -9 -r -q source_code work/

-9 compression in a terminal window

With the selection of files and directories being archived here, the difference between no compression (level 0) and the default compression (level 6) is 400K. The difference between the default compression and the highest level of compression (level 9) is only 4K.

That might not seem much, but for archives containing hundreds or even thousands of files, the small amount of extra compression per file would add up to a worthwhile space saving.

Adding Passwords to ZIP Files

Adding passwords to ZIP files is easy. Use the -e (encrypt) option and you’ll be prompted to enter your password and to re-enter it for verification.

zip -e -r -q source_code work/

Adding passwords to zip files in a terminal window

How to Unzip a ZIP File With the unzip Command

To extract the files from a ZIP file, use the unzip command, and provide the name of the ZIP file. Note that you do need to provide the “.zip” extension.

unzip source_code.zip

the unzip command in a terminal window

As the files are extracted they are listed to the terminal window.

output of unzip in a terminal window

ZIP files don’t carry details of file ownership. All of the files that are extracted have the owner set to the user who is extracting them.

Just like zip, unzip has a -q (quiet) option, so that you do not need to see the file listing as the files are extracted.

unzip -q source_code.zip

unzip -q option in a terminal window

Extracting Files to a Target Directory

To have the files extracted in a specific directory, use the -d (directory) option, and provide the path to the directory you wish the archive to be extracted into.

unzip -q source_code.zip -d ./development

unzip to a target directory in a terminal window

Extract Password Protected ZIP Files

If a ZIP file has been created with a password, unzip will ask you for the password. If you do not provide the correct password, unzip will not extract the files.

unzip -q source_code.zip

the unzip with password command in a terminal window

If you don’t care about your password being seen by others—nor about it being stored in your command history—you can provide the password on the command line with the -P (password) option. (You must use a capital “P.”)

unzip -P fifty.treacle.cutlass -q source_code.zip

unzipping with password option in a terminal window

Excluding Files

If you do not want to extract a particular file or group of files, use the -x (exclude) option. In this example, we want to extract all of the files apart from those ending in a “.h” extension.

unzip -q source_code.zip -x *.h

unzip exclude option in a terminal window

Overwriting Files

Suppose you have extracted an archive but you have deleted a few of the extracted files by mistake.

A quick fix for that would be to extract the files once again. But if you try to extract the ZIP file in the same directory as before, unzip will prompt you for a decision regarding overwriting the files. It will expect one of the following responses.

Apart from the r (rename) response, these responses are case sensitive.

  • y: Yes, overwrite this file
  • n: No, don’t overwrite this file
  • A: All, overwrite all of the files
  • N: None, overwrite none of the files
  • r: Rename, extract this file but give it a new name. You will be prompted for a new name.

overwrite prompts in a terminal window

To force unzip to overwrite any existing files use the -o (overwrite) option.

unzip -o -q source_code.zip

overwrite option in a terminal window

The most efficient way to replace the missing files would be to have unzip only extract any files in the archive that are not in the target directory. To do this, use the -n (never overwrite) option.

unzip -n source_code.zip

unzip with -n never overwrite option in a terminal window

Looking Inside a ZIP File

It is often useful and instructive to see a list of the files inside a ZIP file before you extract it. You can do this with the -l (list archive) option. It is piped through less to make the output manageable.

unzip -l source_code.zip | less

unzip listing option in a terminal window

The output shows the directories and files within the ZIP file, their length and the time and date they were added to the archive. Press “q” to quit from less.

list archive output in a terminal window

There are other ways to peek inside a ZIP file which give different types of information, as we shall see.

Add a Password With the zipcloak Command

If you’ve created a ZIP file but forgot to add a password, what can you do? You can quickly add a password to ZIP file using the zipcloak command. Pass the name of the ZIP file on the command line. You will be prompted for a password. You need to verify the password by entering it a second time.

zipcloak source_code.zip

zipcloak in a terminal window

View File Details With the zipdetails Command

The zipdetails command will show you a lot of information regarding the ZIP file. The only sensible way to handle the amount of output this command can give is to pipe it through less .

zipdetails source_code.zip | less

the zipdetails command in a terminal window

Note that the information will include filenames even if the ZIP file is password protected. This type of information is stored within the ZIP file as meta-data and is not part of the encrypted data.

output of zipdetails in a terminal window

Search Inside the File With the zipgrep Command

The zipgrep command allows you to search within the files in a ZIP file. In the following example, we want to know which files within the ZIP file have the text “keyval.h” in them.

zipgrep keyval.h source_code.zip

the zipgrep command in a terminal window

We can see that the files slang.c and getval.c contain the string “keyval.h”.We can also see that there are two copies of each of these files in different directories in the ZIP file.

View Information With the zipinfo Command

The zipinfo command gives you yet another way to look inside a ZIP file. As before, we pipe the output through less.

zipinfo source_code.zip | less

zipinfo command in a terminal window

From left to right the output shows:

  • The file permissions
  • The version of the tool used to create the ZIP file
  • The original file size
  • A file descriptor (described below)
  • The method of compression (deflation, in this case)
  • The data and time stamp
  • The name of the file and any directory

The file descriptor is made up of two characters. The first character will be a “t” or a “b” to indicate a text or binary file. If it is a capital letter the file is encrypted. The second character may be one of four characters. This character represents what type of meta-data is included for this file: none, an extended local header, an “extra field”, or both.

  • -: If neither exists, the character will be a hyphen
  • l: if there is an extended local header but no extra field
  • x: if there is no extended local header but there is an extra field
  • X: if there is an extended local header and there is an extra field

zipinfo output in a terminal window

Split the File With the zipsplit Command

If you need to send the ZIP file to someone else but there are size restrictions or problems with the transmission of the file, you can use the zipsplit command to split the original ZIP file into a set of smaller ZIP files.

The -n (size) option allows you to set a maximum size for each of the new ZIP files. In this example, we’re splitting the source_code.zip file. We don’t want any of the new ZIP files to be bigger than 100 KB (102400 bytes).

zipsplit -n 102400 source_code.zip

the zipsplit command in a terminal window

The size that you choose cannot be smaller than the size of any of the files in the ZIP file.

Using these commands, you can create your own ZIP files, unzip ZIP files you receive, and perform various other operations on them without ever leaving the Linux terminal.

Dave McKay Dave McKay
Dave McKay first used computers when punched paper tape was in vogue, and he has been programming ever since. He is now a Data Protection Officer and has worked as a freelance programmer, manager of an international software development team, and an IT services project manager. Dave is a Linux evangelist and open source advocate.
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