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If you want to grep recursively in all .eml.gz files in the current directory, you can use:

find . -name *.eml.gz -print0 | xargs -0 zgrep "STRING"

You have to escape the first * so that the shell does not interpret it. -print0 tells find to print a null character after each file it finds; xargs -0 reads from standard input and runs the command after it for each file; zgrep works like grep, but uncompresses the file first.

There's a lot of confusion here because there isn't just one zgrep. I have two versions on my system, zgrep from gzip and zgrep from zutils. The former is just a wrapper script that calls gzip -cdfq. It doesn't support the -r, --recursive switch.¹

The latter is a c++ program and it supports the -r, --recursive option.

Running zgrep --version | head -n 1 will reveal which one (if any) of them is the default:

zgrep (gzip) 1.6

is the wrapper script,

zgrep (zutils) 1.3

is the cpp executable.

If you have the latter you could run:

zgrep 'pattern' -r --format=gz /path/to/dir

Anyway, as suggested, find + zgrep will work equally well with either version of zgrep:

find /path/to/dir -name '*.gz' -exec zgrep -- 'pattern' {} +

If zgrep is missing from your system (highly unlikely) you could try with:

find /path/to/dir -name '*.gz' -exec sh -c 'gzip -cd "$0" | grep -- "pattern"' {} ;

but there's a major downside: you won't know where the matches are as there's no file name prepended to the matching lines .

^{1: because it would be problematic}

ag is a variant of grep, with some nice extra features.

• has -z option for compressed files,


• has many of ack features.


• it is fast

So:

ag -r -z your-pattern-goes-here   folder

If not installed,

apt-get install silversearcher-ag   (debian and friends)

yum install the_silver_searcher     (fedora)

brew install the_silver_searcher    (mac)

Recursion alone is easy:

   -r, --recursive

          Read all files  under  each  directory,  recursively,  following

          symbolic  links  only  if they are on the command line.  This is

          equivalent to the -d recurse option.



   -R, --dereference-recursive

          Read all files under each directory,  recursively.   Follow  all

          symbolic links, unlike -r.

However, for compressed files you need something like:

shopt globstar 

for file in /path/to/directory/**/*gz; do zcat ""$file" | grep pattern; done

path/to/directory should be the parent directory that contains the subdirectories for each day.

zgrep is the obvious answer but, unfortunately, it does not support the -r flag. From man zgrep:

These grep options will cause zgrep to terminate with an error code: (-[drRzZ]|--di*|--exc*|--inc*|--rec*|--nu*).

If your system has zgrep, you can simply

zgrep -irs your-pattern-goes-here the-folder-to-search-goes-here/

If your system does not have zgrep, you can use the find command to run zcat and grep against each file like so:

find the-folder-to-search-goes-here/ -name '*.gz'
-exec sh -c 'echo "Searching {}" ; zcat "{}" | grep your-pattern-goes-here ' ;

xzgrep -l "string" ./*/*.eml.gz

xzgrep is a derivative of the zgrep utils (less /bin/xzgrep)

From the Man page:

xzgrep invokes grep(1) on files which may be either uncompressed or compressed with xz(1), lzma(1), gzip(1), bzip2(1), or lzop(1). All
options specified are passed directly to grep(1).

-l print the matching file name

-R for recursion will not work as it's specifically prohibited in the script, however simple shell globbing should get us there

./*/*.eml.gz

from a relative path where ./today/sample.eml.gz, match on all instances of that are one level below our relative position in the shell, that ends with ".eml.gz"