18.12.2017

The Advent of Void: Day 18: mblaze

Today I want to introduce mblaze(7), a set of Unix utilities to deal with mails stored in the maildir format.

It aims to be used for both interactive usage and scripting, similar to MH or nmh. Except that its mblaze was written from scratch to be performant and memory efficient allowing to work with large amounts of mails. This results in a smaller and clean implementation which dropped support for (in our eyes) less useful features and improve usability.

The basic concept of mblaze is to work with sequences which are newline separated list of mail files with optional indention to represent threading. Sequences can be used in memory by using pipes or as files which enabled further features as explained later in this post.

There are tools to create, sort, filter and manipulate sequences, other tools like mshow, maddr or magrep use those sequences to gather, address or show specific mails from sequences.

mlist(1) creates the initial sequence, It takes mail directories as argument and prints out all the mails it can find, it also has some arguments to filter mails by flags that are stored in the file name, as example -S and -s to show only seen or not seen mails respectively.

$ mlist ~/mail/
/home/duncan/mail/1505313797.1422_503.tux,U=41583:2,S
/home/duncan/mail/1505402355.860_19.tux,U=41679:2,ST
/home/duncan/mail/1505402356.860_24.tux,U=41684:2,S
/home/duncan/mail/1505402355.860_23.tux,U=41683:2,S
/home/duncan/mail/1505402356.860_25.tux,U=41685:2,S
/home/duncan/mail/1505402355.860_22.tux,U=41682:2,
/home/duncan/mail/1505402355.860_20.tux,U=41680:2,S
/home/duncan/mail/1505402356.860_26.tux,U=41686:2,S
/home/duncan/mail/1505313797.1422_502.tux,U=41582:2,ST

Most mails and MUAs work with mails in threads, mblaze has mthread(1) to group the mails in a sequence into threads. To sort mails we use msort(1) which uses mail headers like Date or Subject to sort the sequence in the specified way.

$ mlist ~/mail/ | mthread
/home/duncan/mail//1505402355.860_19.tux,U=41679:2,ST
<voidlinux/void-packages/issues/7614@github.com>
 /home/duncan/mail//1505313797.1422_502.tux,U=41582:2,ST
 /home/duncan/mail//1505313797.1422_503.tux,U=41583:2,S
 /home/duncan/mail//1505402355.860_20.tux,U=41680:2,S
/home/duncan/mail//1505402355.860_22.tux,U=41682:2,
 /home/duncan/mail//1505402355.860_23.tux,U=41683:2,S
 /home/duncan/mail//1505402356.860_24.tux,U=41684:2,S
<voidlinux/void-packages/pull/7639@github.com>
 /home/duncan/mail//1505402356.860_25.tux,U=41685:2,S
 /home/duncan/mail//1505402356.860_26.tux,U=41686:2,S
9 mails threaded
$ mlist ~/mail/ | mthread | msort -d
<voidlinux/void-packages/issues/7614@github.com>
 /home/duncan/mail//1505313797.1422_502.tux,U=41582:2,ST
 /home/duncan/mail//1505313797.1422_503.tux,U=41583:2,S
 /home/duncan/mail//1505402355.860_20.tux,U=41680:2,S
 /home/duncan/mail//1505402355.860_23.tux,U=41683:2,S
 /home/duncan/mail//1505402356.860_24.tux,U=41684:2,S
<voidlinux/void-packages/pull/7639@github.com>
 /home/duncan/mail//1505402356.860_25.tux,U=41685:2,S
 /home/duncan/mail//1505402356.860_26.tux,U=41686:2,S
/home/duncan/mail//1505402355.860_19.tux,U=41679:2,ST
/home/duncan/mail//1505402355.860_22.tux,U=41682:2,
9 mails threaded

To avoid creating and piping sequences every time we can use mseq(1) to save and manipulate mail sequence files. If the sequence is stored as file the mblaze utilities can use the sequence from the file to address mails by index numbers and mmsg(7) selectors.

$ mlist ~/mail/ | mthread | msort -d  | mseq -S
9 mails threaded
$ cat ~/.mblaze/seq
<voidlinux/void-packages/issues/7614@github.com>
 /home/duncan/mail//1505313797.1422_502.tux,U=41582:2,ST
 /home/duncan/mail//1505313797.1422_503.tux,U=41583:2,S
 /home/duncan/mail//1505402355.860_20.tux,U=41680:2,S
 /home/duncan/mail//1505402355.860_23.tux,U=41683:2,S
 /home/duncan/mail//1505402356.860_24.tux,U=41684:2,S
<voidlinux/void-packages/pull/7639@github.com>
 /home/duncan/mail//1505402356.860_25.tux,U=41685:2,S
 /home/duncan/mail//1505402356.860_26.tux,U=41686:2,S
/home/duncan/mail//1505402355.860_19.tux,U=41679:2,ST
/home/duncan/mail//1505402355.860_22.tux,U=41682:2,

Now that the sequence is saved we can continue can use mscan(1) a tool to print one line message lists including the subject, the date and a visual representation for the flags.

$ mscan
                                       \_ <voidlinux/void-packages/issues/7614@github.com>
 x  2   Sun Sep 10 gravicappa            Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
    3   Sun Sep 10 Lain                  Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
    4   Thu Sep 14 Enno Boland           Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
    5   Thu Sep 14 Dominic Monroe        Re: [voidlinux/void-packages] Replace caddy with wedge in light of caddy's new EULA (#7657)
    6   Thu Sep 14 lemmi                 Re: [voidlinux/void-packages] Replace caddy with wedge in light of caddy's new EULA (#7657)
                                       \_ <voidlinux/void-packages/pull/7639@github.com>
    8   Thu Sep 14 Michael Gehring       Re: [voidlinux/void-packages] libcaca: add (optional) support for imlib2 (#7639)
    9   Thu Sep 14 newbluemoon           Re: [voidlinux/void-packages] libcaca: add (implicit) support for imlib2 (#7639)
 x  10  Thu Sep 14 Michael Gehring     Re: [voidlinux/void-packages] libdockapp: Corrected incorrect entry in shlibs (#7652)
 .  11  Thu Sep 14 lemmi               [voidlinux/void-packages] Replace caddy with wedge in light of caddy's new EULA (#7657)
11 mails scanned

The first column is for flags, x is for Trashed mails, and . (dot) for unseen mails, the second column is the index of the mail in the sequence.

mscan can use the previously mentioned mmsg(7) syntax to address or select mails. In this example the first one just addresses two mails by their index, the second example selects a range of mails starting and ending at the specified index.

$ mscan 2 5
 x  2   Sun Sep 10 gravicappa            Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
    5   Thu Sep 14 Dominic Monroe        Re: [voidlinux/void-packages] Replace caddy with wedge in light of caddy's new EULA (#7657)
2 mails scanned
$ mscan 2:5
 x  2   Sun Sep 10 gravicappa            Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
    3   Sun Sep 10 Lain                  Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
    4   Thu Sep 14 Enno Boland           Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
    5   Thu Sep 14 Dominic Monroe        Re: [voidlinux/void-packages] Replace caddy with wedge in light of caddy's new EULA (#7657)
4 mails scanned

The next tool is mshow(1) which renders mails or extracts attachments.

$ mshow 2
From: gravicappa <notifications@github.com>
Subject: Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
To: voidlinux/void-packages <void-packages@noreply.github.com>
Cc: Duncan Overbruck <duncaen@voidlinux.eu>,  Comment <comment@noreply.github.com>
Date: Sun, 10 Sep 2017 09:30:36 -0700 (14 weeks, 1 day, 1 hour ago)
Reply-To: voidlinux/void-packages <reply+002aecdf7dfdc8d5ee7bc8a57eb08b436b6d3af844c59c4192cf0000000115cd2aac92a169ce0f49ca87@reply.github.com>

--- 1: multipart/alternative size=2477 ---
--- --- 2: text/plain size=258 charset="UTF-8" render="mflow -f" ---
It shows cyrillics correctly but inputting whose with keyboard yields nothing.

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mless(1) is a small wrapper around less that lets you page through your sequence. On the top it prints a few lines from mscan with the current mail highlighted and on the bottom it shows the content of the mail. You can now use :n and :p to navigate through mails.

$ mless
 x  3   Sun Sep 10 gravicappa            Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614
    4   Sun Sep 10 Lain                  Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614
>   5   Thu Sep 14 Enno Boland           Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614
 .  6   Thu Sep 14 lemmi               [voidlinux/void-packages] Replace caddy with wedge in light of caddy's new EU
    7   Thu Sep 14 Dominic Monroe        Re: [voidlinux/void-packages] Replace caddy with wedge in light of caddy's
    8   Thu Sep 14 lemmi                 Re: [voidlinux/void-packages] Replace caddy with wedge in light of caddy's

From: Enno Boland <notifications@github.com>
Subject: Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
To: voidlinux/void-packages <void-packages@noreply.github.com>
Cc: Duncan Overbruck <duncaen@voidlinux.eu>,  Comment <comment@noreply.github.com>
Date: Wed, 13 Sep 2017 23:15:15 -0700 (13 weeks, 4 days, 17 hours ago)
Reply-To: voidlinux/void-packages <reply+002aecdfbf62a2c14f84705a7fd3c31678cfae556dcc03ee92cf0000000115d1e07392a169ce0f49ca87@reply.github.com>

--- 1: multipart/alternative size=2827 ---
--- --- 2: text/plain size=197 charset="UTF-8" render="mflow -f" ---
Closed #7614 via #7633.

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~
~
mless 2 (message 3 of 12)

Another tool is mpick(1) which can be used to write extensive filters for mail sequences.

$ mpick -t 'subject =~~ "dmenu"' | mscan
 x  3   Sun Sep 10 gravicappa            Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
    4   Sun Sep 10 Lain                  Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
>   5   Thu Sep 14 Enno Boland           Re: [voidlinux/void-packages] dmenu-4.7 doesn't allow cyrillic input (#7614)
11 mails tested, 3 picked.
3 mails scanned

In the next example mpick only picks mails between two dates and tests if the replied flag is set or the seen flag is not set.

$ mpick -t 'date >= "2017-09-01" && date < "2017-10-01" && (replied || !seen)' | mscan
 .  6   Thu Sep 14 lemmi               [voidlinux/void-packages] Replace caddy with wedge in light of caddy's new EULA (#7657)
11 mails tested, 1 picked.
1 mails scanned

This is just a very small example, mblaze is capable of a lot more and has great man pages that are worth reading, see mblaze(7) and the git repository as starting point if you want to learn more about it.