|Simple Zip File Item Replacer|
Add or replace a zip archive entry from the pipeline
Linux has a /proc filesystem. Opening a file /proc/$PID/fd/$N is equivalent to `dupping' the process' file descriptor into your application.
For any process, /proc/self is an alias of a /proc subdirectory for this process: not only when a file under /proc/self is opened directly, but also when a symbolic link is resolved.
It became a tradition to have /dev/stdin linking to /proc/self/fd/0, /dev/stdout to /proc/self/fd/1, and /dev/stderr to /proc/self/fd/2.
These features of the proc filesystem provide a way to trick the standard zip utility into reading its standard input while thinking that it's a named file.
First, the symbolic link is created (a random subdirectory of /tmp is the most appropriate place for it). The target would be /dev/stdin (or /proc/self/fd/0), and the name of the link itself is the desirable name of file in the archive:
DIR=`mktemp -d` cd $DIR ln -s /dev/stdin desiredName.txt
Then the standard zip archiver may be invoked in the pipeline:
do something hard | zip -FI ..../archive.zip desiredName.txt
It reads desiredName.txt and updates the archive, completely unaware that this file is its own standard input. Option -FI is required at least for some zip versions, or else it refuses to archive a FIFO (unnamed pipe pointed by desiredName.txt link is a FIFO, of course).
The pipeline below is all you need for the same task, if you installed zipput.
do something hard | zipput ..../archive.zip desiredName.txt
On the one hand, zipput is portable. On the other hand, it requires libzip. On the third hand... well, libzip is also portable.
If you have libzip, both library and header, at your system, something like
cc -o zipput zipput.c -lzipwould be enough to get zipput executable. Of course, you may prefer
gcc -pedantic -ansi -Wall -W -Werror \ -O4 -std=c89 -Wl,--strip-all zipput.c -lzipBut it doesn't make much of a difference, so why bother.
If you are lucky to have a Debian GNU/Linux Lenny system, there is a repository, kindly provided by Mobigroup. Anyway, it's worthy of having it it in your /etc/apt/sources.list, for much more useful things than Zipput.
deb http://mobigroup.ru/debian/ lenny main contrib non-free deb-src http://mobigroup.ru/debian/ lenny main contrib non-freeDon't forget to install debian-mobigroup-keyring for package verification. Debian-like or debian-based distributions have some chance to work with many packages of this collection, especially with the trivial thingy like zipput.