Pipe Tar Extract into Tar Create

How to extract tar archive from stdin?

Use - as the input file:

cat largefile.tgz.aa largefile.tgz.ab | tar zxf -

Make sure you cat them in the same order they were split.

If you're using zsh you can use the multios feature and avoid invoking cat:

< largefile.tgz.aa < largefile.tgz.ab tar zxf -

Or if they are in alphabetical order:

<largefile.tgz.* | tar zxf -

How can I build a tar from stdin?

Something like:

tar cfz foo.tgz --files-from=-

But keep in mind that this won't work for all possible filenames; you should consider the --null option and feed tar from find -print0. (The xargs example won't quite work for large file lists because it will spawn multiple tar commands.)

how to pipe contents of large tar.gz file to STDOUT?

Use this with GNU tar to extract a tgz to stdout:

tar -xOzf large.tar.gz --wildcards '*.html' | grep ...

-O, --to-stdout: extract files to standard output

shell-scripting: Use a pipe as an input for tar

I don't see how "tar" figures into this at all; why not just compress the dump file itself?

pg_dump -U myUser myDB | gzip > myDB.sql.gz

Then, to restore:

gzip -cd myDB.sql.gz | pg_restore ...

The "tar" utility is for bundling up a bunch of files and directories into a single file (the name is a contraction of "tape archive"). In that respect, a "tar" file is kind-of like a "zip" file, except that "zip" always implies compression while "tar" does not.

Note finally that "gzip" is not "zip." The "gzip" utility just compresses; it doesn't make archives.

How would I tar extract pipe cd?

Pipes link up the output of one program to the input of another - just how a pipe sends the output from your garden tap (faucet) to your lawn sprinkler.

A minus sign (-) is a shortcut meaning either input or output - which one it means depends on position/context.

Your wget command grabs some data from the web and, because of the -, sends it through a pipe to tar.

The tar command reads that data from the pipe, because of its -, and creates some files and directories.

The tar command doesn't send anything down any further pipes, so there'd be nothing for cd to read. You also don't know the name of the directory you want to go to. If you did, you could go there as a follow-up action like this:

wget ... - | tar ... - ; cd SOMEWHERE

Or you could make it conditional on the tar command running successfully with:

wget ... - | tar ... - && cd SOMEWHERE

Linux Pipe viewer, how to split the pipe

Not sure that your original command works, as there are several errors in the options given to tar.

Given that ../MyFolder exists, your first command need to be

    pv large_file.tar.gz | tar -xz -C ../MyFolder

If you insert tee call between pv and tar calls, then the whole chain works.

    pv large_file.tar.gz | tee /tmp/strout.log | tar -xz -C ../MyFolder

However i'm not sure it does what you expect. If you pipe pv output to tee, tee will pipe it to tar, and dump the same contents as the original tar to /tmp/strout.log, resulting in your tar extracted to ../MyFolder and copied to /tmp/strout.log.

EDIT
As suggested by @DownloadPizza, you can use process substitution (see How do I write stderr to a file while using "tee" with a pipe?). By using -f flag with pv, your command will become

    pv -f large_file.tar.gz 2> >(tee /tmp/strout.log) > >(tar -xz -C ../MyFolder)

and will produce expected output.