There are quite a few interesting things that you can do with "zip" commands other than compress and uncompress files. Here are some other zip options and how they can help. Credit: Clare Black Some of us have been zipping files on Unix and Linux systems for many decades — to save some disk space and package files together for archiving. Even so, there are some interesting variations on zipping that not all of us have tried. So, in this post, we’re going to look at standard zipping and unzipping as well as some other interesting zipping options. The basic zip command First, let’s look at the basic zip command. It uses what is essentially the same compression algorithm as gzip, but there are a couple important differences. For one thing, the gzip command is used only for compressing a single file where zip can both compress files and join them together into an archive. For another, the gzip command zips “in place”. In other words, it leaves a compressed file — not the original file alongside the compressed copy. Here’s an example of gzip at work: $ gzip onefile $ ls -l -rw-rw-r-- 1 shs shs 10514 Jan 15 13:13 onefile.gz And here’s zip. Notice how this command requires that a name be provided for the zipped archive where gzip simply uses the original file name and adds the .gz extension. $ zip twofiles.zip file* adding: file1 (deflated 82%) adding: file2 (deflated 82%) $ ls -l -rw-rw-r-- 1 shs shs 58021 Jan 15 13:25 file1 -rw-rw-r-- 1 shs shs 58933 Jan 15 13:34 file2 -rw-rw-r-- 1 shs shs 21289 Jan 15 13:35 twofiles.zip Notice also that the original files are still sitting there. The amount of disk space that is saved (i.e., the degree of compression obtained) will depend on the content of each file. The variation in the example below is considerable. $ zip mybin.zip ~/bin/* adding: bin/1 (deflated 26%) adding: bin/append (deflated 64%) adding: bin/BoD_meeting (deflated 18%) adding: bin/cpuhog1 (deflated 14%) adding: bin/cpuhog2 (stored 0%) adding: bin/ff (deflated 32%) adding: bin/file.0 (deflated 1%) adding: bin/loop (deflated 14%) adding: bin/notes (deflated 23%) adding: bin/patterns (stored 0%) adding: bin/runme (stored 0%) adding: bin/tryme (deflated 13%) adding: bin/tt (deflated 6%) The unzip command The unzip command will recover the contents from a zip file and, as you’d likely suspect, leave the zip file intact, whereas a similar gunzip command would leave only the uncompressed file. $ unzip twofiles.zip Archive: twofiles.zip inflating: file1 inflating: file2 $ ls -l -rw-rw-r-- 1 shs shs 58021 Jan 15 13:25 file1 -rw-rw-r-- 1 shs shs 58933 Jan 15 13:34 file2 -rw-rw-r-- 1 shs shs 21289 Jan 15 13:35 twofiles.zip The zipcloak command The zipcloak command encrypts a zip file, prompting you to enter a password twice (to help ensure you don’t “fat finger” it) and leaves the file in place. You can expect the file size to vary a little from the original. $ zipcloak twofiles.zip Enter password: Verify password: encrypting: file1 encrypting: file2 $ ls -l total 204 -rw-rw-r-- 1 shs shs 58021 Jan 15 13:25 file1 -rw-rw-r-- 1 shs shs 58933 Jan 15 13:34 file2 -rw-rw-r-- 1 shs shs 21313 Jan 15 13:46 twofiles.zip Keep in mind that the original files are still sitting there unencrypted. The zipdetails command The zipdetails command is going to show you details — a lot of details about a zipped file, likely a lot more than you care to absorb. Even though we're looking at an encrypted file, zipdetails does display the file names along with file modification dates, user and group information, file length data, etc. Keep in mind that this is all "metadata." We don't see the contents of the files. $ zipdetails twofiles.zip 0000 LOCAL HEADER #1 04034B50 0004 Extract Zip Spec 14 '2.0' 0005 Extract OS 00 'MS-DOS' 0006 General Purpose Flag 0001 [Bit 0] 1 'Encryption' [Bits 1-2] 1 'Maximum Compression' 0008 Compression Method 0008 'Deflated' 000A Last Mod Time 4E2F6B24 'Tue Jan 15 13:25:08 2019' 000E CRC F1B115BD 0012 Compressed Length 00002904 0016 Uncompressed Length 0000E2A5 001A Filename Length 0005 001C Extra Length 001C 001E Filename 'file1' 0023 Extra ID #0001 5455 'UT: Extended Timestamp' 0025 Length 0009 0027 Flags '03 mod access' 0028 Mod Time 5C3E2584 'Tue Jan 15 13:25:08 2019' 002C Access Time 5C3E27BB 'Tue Jan 15 13:34:35 2019' 0030 Extra ID #0002 7875 'ux: Unix Extra Type 3' 0032 Length 000B 0034 Version 01 0035 UID Size 04 0036 UID 000003E8 003A GID Size 04 003B GID 000003E8 003F PAYLOAD 2943 LOCAL HEADER #2 04034B50 2947 Extract Zip Spec 14 '2.0' 2948 Extract OS 00 'MS-DOS' 2949 General Purpose Flag 0001 [Bit 0] 1 'Encryption' [Bits 1-2] 1 'Maximum Compression' 294B Compression Method 0008 'Deflated' 294D Last Mod Time 4E2F6C56 'Tue Jan 15 13:34:44 2019' 2951 CRC EC214569 2955 Compressed Length 00002913 2959 Uncompressed Length 0000E635 295D Filename Length 0005 295F Extra Length 001C 2961 Filename 'file2' 2966 Extra ID #0001 5455 'UT: Extended Timestamp' 2968 Length 0009 296A Flags '03 mod access' 296B Mod Time 5C3E27C4 'Tue Jan 15 13:34:44 2019' 296F Access Time 5C3E27BD 'Tue Jan 15 13:34:37 2019' 2973 Extra ID #0002 7875 'ux: Unix Extra Type 3' 2975 Length 000B 2977 Version 01 2978 UID Size 04 2979 UID 000003E8 297D GID Size 04 297E GID 000003E8 2982 PAYLOAD 5295 CENTRAL HEADER #1 02014B50 5299 Created Zip Spec 1E '3.0' 529A Created OS 03 'Unix' 529B Extract Zip Spec 14 '2.0' 529C Extract OS 00 'MS-DOS' 529D General Purpose Flag 0001 [Bit 0] 1 'Encryption' [Bits 1-2] 1 'Maximum Compression' 529F Compression Method 0008 'Deflated' 52A1 Last Mod Time 4E2F6B24 'Tue Jan 15 13:25:08 2019' 52A5 CRC F1B115BD 52A9 Compressed Length 00002904 52AD Uncompressed Length 0000E2A5 52B1 Filename Length 0005 52B3 Extra Length 0018 52B5 Comment Length 0000 52B7 Disk Start 0000 52B9 Int File Attributes 0001 [Bit 0] 1 Text Data 52BB Ext File Attributes 81B40000 52BF Local Header Offset 00000000 52C3 Filename 'file1' 52C8 Extra ID #0001 5455 'UT: Extended Timestamp' 52CA Length 0005 52CC Flags '03 mod access' 52CD Mod Time 5C3E2584 'Tue Jan 15 13:25:08 2019' 52D1 Extra ID #0002 7875 'ux: Unix Extra Type 3' 52D3 Length 000B 52D5 Version 01 52D6 UID Size 04 52D7 UID 000003E8 52DB GID Size 04 52DC GID 000003E8 52E0 CENTRAL HEADER #2 02014B50 52E4 Created Zip Spec 1E '3.0' 52E5 Created OS 03 'Unix' 52E6 Extract Zip Spec 14 '2.0' 52E7 Extract OS 00 'MS-DOS' 52E8 General Purpose Flag 0001 [Bit 0] 1 'Encryption' [Bits 1-2] 1 'Maximum Compression' 52EA Compression Method 0008 'Deflated' 52EC Last Mod Time 4E2F6C56 'Tue Jan 15 13:34:44 2019' 52F0 CRC EC214569 52F4 Compressed Length 00002913 52F8 Uncompressed Length 0000E635 52FC Filename Length 0005 52FE Extra Length 0018 5300 Comment Length 0000 5302 Disk Start 0000 5304 Int File Attributes 0001 [Bit 0] 1 Text Data 5306 Ext File Attributes 81B40000 530A Local Header Offset 00002943 530E Filename 'file2' 5313 Extra ID #0001 5455 'UT: Extended Timestamp' 5315 Length 0005 5317 Flags '03 mod access' 5318 Mod Time 5C3E27C4 'Tue Jan 15 13:34:44 2019' 531C Extra ID #0002 7875 'ux: Unix Extra Type 3' 531E Length 000B 5320 Version 01 5321 UID Size 04 5322 UID 000003E8 5326 GID Size 04 5327 GID 000003E8 532B END CENTRAL HEADER 06054B50 532F Number of this disk 0000 5331 Central Dir Disk no 0000 5333 Entries in this disk 0002 5335 Total Entries 0002 5337 Size of Central Dir 00000096 533B Offset to Central Dir 00005295 533F Comment Length 0000 Done The zipgrep command The zipgrep command is going to use a grep-type feature to locate particular content in your zipped files. If the file is encrypted, you will need to enter the password provided for the encryption for each file you want to examine. If you only want to check the contents of a single file from the archive, add its name to the end of the zipgrep command as shown below. $ zipgrep hazard twofiles.zip file1 [twofiles.zip] file1 password: Certain pesticides should be banned since they are hazardous to the environment. The zipinfo command The zipinfo command provides information on the contents of a zipped file whether encrypted or not. This includes the file names, sizes, dates and permissions. $ zipinfo twofiles.zip Archive: twofiles.zip Zip file size: 21313 bytes, number of entries: 2 -rw-rw-r-- 3.0 unx 58021 Tx defN 19-Jan-15 13:25 file1 -rw-rw-r-- 3.0 unx 58933 Tx defN 19-Jan-15 13:34 file2 2 files, 116954 bytes uncompressed, 20991 bytes compressed: 82.1% The zipnote command The zipnote command can be used to extract comments from zip archives or add them. To display comments, just preface the name of the archive with the command. If no comments have been added previously, you will see something like this: $ zipnote twofiles.zip @ file1 @ (comment above this line) @ file2 @ (comment above this line) @ (zip file comment below this line) If you want to add comments, write the output from the zipnote command to a file: $ zipnote twofiles.zip > comments Next, edit the file you've just created, inserting your comments above the (comment above this line) lines. Then add the comments using a zipnote command like this one: $ zipnote -w twofiles.zip The zipsplit command The zipsplit command can be used to break a zip archive into multiple zip archives when the original file is too large — maybe because you're trying to add one of the files to a small thumb drive. The easiest way to do this seems to be to specify the max size for each of the zipped file portions. This size must be large enough to accomodate the largest included file. $ zipsplit -n 12000 twofiles.zip 2 zip files will be made (100% efficiency) creating: twofile1.zip creating: twofile2.zip $ ls twofile*.zip -rw-rw-r-- 1 shs shs 10697 Jan 15 14:52 twofile1.zip -rw-rw-r-- 1 shs shs 10702 Jan 15 14:52 twofile2.zip -rw-rw-r-- 1 shs shs 21377 Jan 15 14:27 twofiles.zip Notice how the extracted files are sequentially named "twofile1" and "twofile2". Wrap-up The zip command, along with some of its zipping compatriots, provide a lot of control over how you generate and work with compressed file archives. Related content how-to Compressing files using the zip command on Linux The zip command lets you compress files to preserve them or back them up, and you can require a password to extract the contents of a zip file. By Sandra Henry-Stocker May 13, 2024 4 mins Linux opinion NSA, FBI warn of email spoofing threat Email spoofing is acknowledged by experts as a very credible threat. 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