On Sun, 31 Aug 2003 [EMAIL PROTECTED] wrote:
> Adapting zmore for the case where you specify the files to display on
> the command line is not problem at all:
>
> > diff kk zmore
> 5,14d4
> < get_decompressor ()
> < {
> < case `file ${1--} | sed "s/[^:]*: *\([^ ]*\).*/\1/"` in
> < "compress"*) DECOMPRESSOR="uncompress -c";;
> < "gzip"*) DECOMPRESSOR="gzip -cdfq";;
> < "bzip2"*) DECOMPRESSOR="bunzip2 -cdq";;
> < *) DECOMPRESSOR="cat";;
> < esac
> < }
> <
> 56,57c46
> < get_decompressor ${FILE}
> < ${DECOMPRESSOR} "$FILE" | eval ${PAGER-more}
> ---
> > gzip -cdfq "$FILE" | eval ${PAGER-more}
>
> But when zmore is used as a pipe or with input redirection, things become
> more complicated.
>
> gzip -cdfq | eval ${PAGER-more}
>
> In order to detect the type of data passed on STDIN, the get_decompressor
> function or any other means of detection would consume STDIN. STDIN, however
> must be passed to the decompressor after the type of data has been
> detected. I don't have an idea hot to 'duplicate' STDIN, so it could be
As a somewhat ugly hack, you could read a few bytes, match against
known magic numbers and then prepend those bytes to the stream before
feeding to the decompressor, for the cost of an extra "cat" process:
magic=$(dd bs=1 count=3 2>/dev/null)
case $magic in
BZh) DECOMPRESSOR=bunzip2;;
*) DECOMPRESSOR="gzip -cdfq";;
esac
(echo -n "$magic"; exec cat) | $DECOMPRESSOR | eval ${PAGER-more}
Note that gzip will handle compressed data and gzipped data as
well as plain text.
$.02,
/Mikko
> consumed twice. Sure, writing it to a temporary file would be a
> workaround:
>
> 38,53c28
> < FILE="/tmp/.zmore.${$}"
> < touch ${FILE} 2>/dev/null
> < if [ "${?}" -ne "0" ]; then
> < echo "can't create temporary file"
> < exit 1
> < fi
> < chmod 0600 ${FILE}
> < cat >${FILE}
> < if [ "${?}" -ne "0" ]; then
> < echo "can't create temporary file"
> < rm -f ${FILE}
> < exit 1
> < fi
> < get_decompressor ${FILE}
> < cat ${FILE} | ${DECOMPRESSOR} | eval ${PAGER-more}
> < rm -f ${FILE}
> ---
> > gzip -cdfq | eval ${PAGER-more}
>
> But I don't like that. I myself sometimes work with compressed files
> larger than anything I would be happy to write to /tmp or somewhere else
> (even though those cases usually rather use zcat and its cousinds than
> zmore...)
>
> Kurt
>
> On Sat, Aug 30, 2003 at 12:21:45PM -0400, Chuck Swiger wrote:
> > David Kelly wrote:
> > [ ... ]
> > > Yes, of course. But zmore is smart enough to figure out what to do with
> > > several compression techniques, or even to handle non-compressed files
> > > very trivially and without hassle.
> >
> > 'zmore' is a simple shell script which calls "gzcat | ${PAGER-more}". One
> > solution to your problem, or at least a solution, would be to change zmore to
> > look for a trailing bz/bz2 or invoke bzcat instead. Another would be to change
> > the sources of gzip to recognize the bzip2 magic files bytes, extending the
> > detection of gzip versus classic LZH used by compress.
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