provide a 7zcat alias and a way to compress directly from stdin to stdout

[Everthon Valadão]

Binary package hint: p7zip

1) Sometimes you just want to "grep" someting in a compressed text file, but it is too big to be decompressed and then processed. This is why I love zcat and bzcat: I could decompress and pipe it on the flow to grep/awk/whatever, but unfortunately I do not see a 7zip cat like. 7zip command line options are too many and hard to remember, so I put this alias in my ~/.bashrc:

    alias 7zcat='7za e $@ -so 2> /dev/null'

I wish this alias came pre-installed with p7zip :-)
OBS.: the redirection of stderr to /dev/null is because 7z doesn't have a --quiet option (could you fix this too?)

2) I wonder if there is some way to compress with 7zip exactly like I do with gzip:
    echo "foo" | gzip -c > foo.gz
The 7zip manpage gives this example (with gzip compression):
    echo "foo" | 7za a dummy -tgzip -si -so > foo.gz
but with 7zip compression, the closest I got was
    echo "foo" | 7za a -t7z -si foo.7z
so, how to redirect the output to /dev/stdout when reading from /dev/stdin? I mean, it is this possible via some bash-fu, named pipes, etc?

original source: http://mobilevs.blogspot.com/2009/06/7zcat.html

[Mohammed Adnène Trojette (adn+ubuntu)]

On Thu, Jun 04, 2009, Everthon Valadão wrote:
> (snip)
> alias 7zcat='7za e $@ -so 2> /dev/null'
> (snip)
> 2) I wonder if there is some way to compress with 7zip exactly like I do with gzip:
> (snip)

You should use lzma.

--
Mohammed Adnène Trojette