aside from cat?
On Thu, Nov 29, 2018 at 03:07:58PM -0800, Joseph Tam wrote:
> On Thu, 29 Nov 2018, Marc Roos wrote:
>
> >When concatenating mbox files like described here
> >https://xaizek.github.io/2013-03-30/merge-mbox-mailboxes/. You will end
> >up with an 'unsorted' mbox file. Is this going to be a problem
> >esspecially when they are large >2GB's and new emails will be written to
> >it?
>
> I don't think it will be a problem, but you might have to remove
> some headers (like the UUID header?). However, I think dovecot
> ought to be able to cope with it anyways and regenerate the indices.
>
> >The email client nicely sorts the message from folder A "foldera 5 last"
> >as last, but of course the mbox is not like this.
> >Is there a better solution for merging files?
>
> As noted, the time order gets scrambled -- using your mail reader to
> get it back in time order requires sorting, an intensive operation.
>
> It just so happen I've done this recently with a (GNU) awk script that
> merges multiple mailboxes into one mailbox, preserving time order.
> It assumes that each message starst with a From envelopes header with
> sorted timestamps e.g.
>
> From [email protected] Thu Nov 25 18:45:37 2018
> From [email protected] Thu Nov 25 18:45:37 2018 -0400
>
> Your're welcome to use it. There's probably a more elegant way with
> doveadm/dsync. Using a mail reader to sort the merged mailbox, then
> drag/drop/copy everything into a final mailbox could also work.
>
> Joseph Tam <[email protected]>
>
> #!/bin/sh
> #
> # Merge multiple mbox's into one assuming that each message
> # starts with /^From .* {year}$/ and they are sorted by time.
> #
> # -- Joseph Tam <[email protected]>
> #
>
> [ x"$*" = x ] && {
> echo "Usage: $0 mbox-file ..."
> exit 1
> }
>
> gawk -v boxes="$*" </dev/null '
> function Tstamp(header) {
> # Format: Jan 22 21:00:48 2018 -0700
> # 12345678901234567890123456
> l = length(header)
> spec = (substr(header,l-4,1)=="-")? substr(header,l-25,20) :
> substr(header,l-19,20)
> spec = substr(spec,17,4) " " ym[substr(spec,1,3)]
> substr(spec,4,3) \
> " " substr(spec,8,2) " " substr(spec,11,2) " "
> substr(spec,14,2)
> return int(mktime(spec))
>
> }
>
> function DumpMessage(i) {
> if (header[i]!="") {
> printf("%s\n",header[i])
> }
> while ((getline x <mbox[i])>0) {
> if (x~/^From .*[0-9][0-9][0-9][0-9]$/) {
> stamp[i] = Tstamp(x)
> header[i] = x
> printf("%s => [%d] %d\n",header[i],i,stamp[i])
> >"/dev/stderr"
> return
> }
> print x
> }
>
> printf("EOF[%d]\n",i) >"/dev/stderr"
> stamp[i] = 2147483647
> header[i] = ""
> }
>
> BEGIN {
> ym["Jan"] = "01"; ym["Feb"] = "02"; ym["Mar"] = "03";
> ym["Apr"] = "04"
> ym["May"] = "05"; ym["Jun"] = "06"; ym["Jul"] = "07";
> ym["Aug"] = "08"
> ym["Sep"] = "09"; ym["Oct"] = "10"; ym["Nov"] = "11";
> ym["Dec"] = "12"
>
> n = split(boxes,mbox," ")
>
> # Read first header line from all boxes
> for (i=1; i<=n; i++) {
> DumpMessage(i)
> }
>
> # Loop until all maiboxes read
> while (1) {
> t = 2147483646
>
> # Find next message
> for (i=1; i<=n; i++) {
> if (stamp[i]<=t) {t=stamp[i]; j=i;}
> }
>
> # If no more message, quit
> if (t==2147483646) exit
>
> # Dump next message from mbox[j]
> DumpMessage(j)
> }
> }'
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