[Dovecot] compression script for use with zlib module

[fernando at dfcom.com.br]

Hi,

I´m using the following two scripts:

zip-list.sh:

find "$home" \
        -type f \
        -name '*,S=*' \
        -mtime +1 \
        -size +10k

The above script list the files that will be compressed.

zip-compressh.sh
#!/bin/bash

uid='vmail'
gid='vmail'

sleepOnFailure='2'

cat zip-list.txt|while read i
do
        if [ ! -f "$i" ]
        then
                continue
        fi

        type=$(file -bi "$i")
        fgrep 'message/rfc822' <<<"$type" >/dev/null
        if [ "$?" != '0' ]
        then
                continue;
        fi

        echo -n "$i..."

        modify=$(stat -c %y "$i"|cut -d. -f1)
        basename=$(basename "$i")

        gzip -9 -c "$i" >/tmp/"$basename"

        mv /tmp/"$basename" "$i"
        exitStatus="$?"
        while [ -f "$i" -a "$exitStatus" != '0' ]
        do
                echo -n "wait($sleepOnFailure)..."
                sleep "$sleepOnFailure"
                mv /tmp/"$basename" "$i" 2>/dev/null
                exitStatus="$?"
        done

        chown "$uid"."$gid" "$i"
        touch -m -d "$modify" "$i"

        echo "OK"
done

This script reads the zip-list.txt and compress the file. We do not lock
the maildir, but we use touch to maintain original dates. We do not check
any 'Z' flags.

[]s
Fernando

>
>     Hi,
>
>     I'm wondering if someone already implemented a compression script
> (and would like to share it) based on the step-by-step provided on wiki
> page of Zlib module.
>
>     I can already do some find|xargs gzip .... but couldnt implement it
> completly as described on the wiki page. I know the suggested
> step-by-step is very detailed and probably a must simplier will be
> enough for almost anyone .... anyway, if someone have the full script
> and would like to share it, i would be glad to get it :)
>
>
> http://wiki.dovecot.org/Plugins/Zlib
>
>
> 1) Find the mails you want to compress in a single maildir.
> 2) Compress the mails to tmp/
>     * Update the compressed files' mtimes to be the same as they were in
> the original files (e.g. touch command)
> 3) Run maildirlock <path> <timeout>. It writes PID to stdout, save it.
>     * <path> is path to the Maildir's dovecot-uidlist (the control
> directory, if it's separate)
>     * <timeout> specifies how long to wait for the lock before failing.
> 4) If maildirlock grabbed the lock successfully (exit code 0) you can
> continue.
> 5) For each mail you compressed:
>    1. Verify that it still exists where you last saw it.
>    2. If it doesn't exist, delete the compressed file. Its flags may
> have been changed or it may have been expunged. This happens rarely, so
> just let the next run handle it.
>    3. If the file does exist, rename() (mv) the compressed file over the
> original file.
>           * Dovecot can now read the file, but to avoid compressing it
> again on the next run, you'll probably want to rename it again to
> include e.g. a "Z" flag in the file name to mark that it was compressed
> (e.g. 1223212411.M907959P17184.host,S=3271:2,SZ). Remember that the
> Maildir specifications require that the flags are sorted by their ASCII
> value, although Dovecot itself doesn't care about that.
> 6) Unlock the maildir by sending a TERM signal to the maildirlock
> process (killing the PID it wrote to stdout).
>
>
>
> --
>
>
> 	Atenciosamente / Sincerily,
> 	Leonardo Rodrigues
> 	Solutti Tecnologia
> 	http://www.solutti.com.br
>
> 	Minha armadilha de SPAM, NÃO mandem email
> 	gertrudes at solutti.com.br
> 	My SPAMTRAP, do not email it
>