You can use gzip *

Note:

• This will zip each file individually and DELETE the original.
• Use -k (--keep) option to keep the original files.
• This may not work if you have a huge number of files due to limits of the shell
• To run gzip in parallel see @MarkSetchell's answer below.

gzip will always compress each file into a single .gz file when given a list of files on its command line.

For example

$ gzip -r log.2011

to recursively walk the log.2011 directory and compress all files it finds, or

$ gzip log.2011/*

to compress only the files in the log.2011 directory without descending into subdirectories.

tar -zcvf compressFileName.tar.gz folderToCompress

everything in folderToCompress will go to compressFileName

Edit: After review and comments I realized that people may get confused with compressFileName without an extension. If you want you can use .tar.gz extension(as suggested) with the compressFileName

Putting every file into a separate tar file doesn't make any sense in this scenario. You can use gzip to compress them directly:

gzip *

will result in file1.out.gz, file2.out.gz etc.

You would use tar only if you would need a compressed archive as a single file.

If you ineed need a tar archive for every file, you can create it like so:

for i in *; do tar -czf i; done

No.

Unlike zip, gzip functions as a compression algorithm only.

Because of various reasons some of which hearken back to the era of tape drives, Unix uses a program named tar to archive data, which can then be compressed with a compression program like gzip, bzip2, 7zip, etc.

In order to "zip" a directory, the correct command would be

tar -zcvf archive.tar.gz directory/ 

This will tell tar to

• compress it using the z (gzip) algorithm

• c (create) an archive from the files in directory (tar is recursive by default)

• v (verbosely) list (on /dev/stderr so it doesn't affect piped commands) all the files it adds to the archive.

• and store the output as a f (file) named archive.tar.gz

The tar command offers gzip support (via the -z flag) purely for your convenience. The gzip command/lib is completely separate. The command above is effectively the same as

tar -cv directory | gzip > archive.tar.gz

To decompress and unpack the archive into the current directory you would use

tar -zxvf archive.tar.gz

That command is effectively the same as

gunzip < archive.tar.gz | tar -xv

tar has many, many, MANY other options and uses as well; I heartily recommend reading through its manpage sometime.

I would use

find /path/to/dir \( -name '*.css' -o -name '*.html' \) -exec gzip --verbose --keep {} \;

Change name to iname if you want to match the extensions case-insensitively (i.e. include .CSS and/or .HTML extensions). You can omit the /path/to/dir if you want to start the recursive search from the current directory.

I'd prefer gzip -r ./ which does the same thing but is shorter.

How about just this?

$ gunzip *.txt.gz

gunzip will create a gunzipped file without the .gz suffix and remove the original file by default (see below for details). *.txt.gz will be expanded by your shell to all the files matching.

This last bit can get you into trouble if it expands to a very long list of files. In that case, try using find and -exec to do the job for you.

From the man page gzip(1):

gunzip takes a list of files on its command line and  replaces  each  file
whose  name  ends  with  .gz, -gz, .z, -z, or _z (ignoring case) and which
begins with the correct magic number with an uncompressed file without the
original  extension.

Note about 'original name'

gzip can store and restore the filename used at compression time. Even if you rename the compressed file, you can be surprised to find out it restores to the original name again.

From the gzip manpage:

By default, gzip keeps the original file name and timestamp in the compressed file. These are used when decompressing the file with the -N option. This is useful when the compressed file name was truncated or when the time stamp was not preserved after a file transfer.

And these file names stored in metadata can also be viewed with file:

$ echo "foo" > myfile_orig
$ gzip myfile_orig 
$ mv myfile_orig.gz myfile_new.gz 
$ file myfile_new.gz 
myfile_new.gz: gzip compressed data, was "myfile_orig", last modified: Mon Aug  5 08:46:39 2019, from Unix
$ gunzip myfile_new.gz        # gunzip without -N
$ ls myfile_*
myfile_new

$ rm myfile_*
$ echo "foo" > myfile_orig
$ gzip myfile_orig
$ mv myfile_orig.gz myfile_new.gz 
# gunzip with -N
$ gunzip -N myfile_new.gz     # gunzip with -N
$ ls myfile_*
myfile_orig

Two questions: 1) What did I do wrong with the syntax?

Gzip only compresses individual files; it's not an archiving tool. It's usually used in combination with something like tar. In fact, some versions of tar will use gzip to automatically create a compressed archive if given appropriate flags. For example:

tar -cvz -f public_html.tar.gz /home/site/public_html/

This creates (-c) a gzip-compressed (-z) archive called public_html.tar.gz containing the contents of the specified public_html directory.

2) How can I revert all of the filenames back to what they were before (exactly what they are now, minus the .gz extension).

Just run gunzip on all the files. E.g:

gunzip -r /home/site/public_html/

Note that you can also simply use the zip command, which will create a single compressed archive.

gzip will compress 1+ files, though not meant to function like an archive utility. The posted cmd-line would yield N compressed file images concatenated to stdout, redirected to the named output file; unfortunately stuff like filenames and any dirs would not be recorded. A pair like this should work:

(create)

tar -czvf dir.tar.gz <some-dir>

(extract)

tar -xzvf dir.tar.gz