[Gllug] Stories of using filters

[Russell Howe]

On Thu, Mar 17, 2005 at 06:41:00AM +0000, Steve Nelson wrote:

> Would people like to contribute some real-life examples of using:
> 
> od, nl, paste, tr, cut, fmt, expand, join, pr, cut, tac, split

Using none of the above... :)

Replacement for dpkg -S which is quite a bit faster:

find /var/lib/dpkg/info/ -maxdepth 1 -name '*.list' -print0 \
	|xargs -0 -P 0 -r grep "$1"                         \
	|sed -e 's,/var/lib/dpkg/info/\([^:]\+\).list:,\1: ,'

As an aside, here's a bit of shell script I wrote: Load it into vim and
watch the syntax hilighting break:

netmask_to_cidr() {
        echo "$1"| (
                IFS=.
                read NM1 NM2 NM3 NM4

                NMDEC="$(((NM1 << 24) + (NM2 << 16) + (NM3 << 8) + NM4
))"

                if [ "$NMDEC" -gt $((0xffffffff)) -o "$NMDEC" -lt 0 ];
then
                        echo "Invalid IPv4 netmask!" >&2
                        exit 1
                fi

                NM_BITS=0
                while [ "$NMDEC" -ne 0 ]; do
                        NMDEC="$(((NMDEC << 1) & 0xffffffff))"
                        NM_BITS="$((NM_BITS + 1))"
                done

                return "$NM_BITS"
        )
}

-- 
Russell Howe       | Why be just another cog in the machine,
rhowe at siksai.co.uk | when you can be the spanner in the works?
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