December 9, 2023 by Roberto Puzzanghera 23 comments

daemontools is a collection of tools for managing UNIX services. It monitors qmail services and saves error messages to one or more logs.


  • Dec 9, 2023
    -moved my patched daemontools to github and named 0.77 the new version
    -clear service moved to qmail/supervise/clear
  • Sep 3, 2023
    -Buffer Overflow fixed in timestamp.c (patch multilog-readable_datetime, Ubuntu 22.04). It was causing empty log files. (thanks Bai Borko and KPC)
  • Jun 30, 2023
    -added my multilog_readable-datetime patch which replaces the timestamp in the log lines with a human readable datetime:

    2023-06-28 16:17:26.501272173 tcpserver: status: 0/200/0
    Do not install it if you prefer to stick with the timestamp.
    - if you install this patch you have to download again the convert-multilog program. In case you decide to stick with the original timestamp, then use the original one. (diff)
    - Finally you have to adjust this line in your qmail-smtpd/log/run and qmail-smtpsd/log/run files:
    - n5 s16777215 '-*' '+* qlog*' !/usr/local/bin/archive_qmail_qlog $LOGDIRQLOG
    + n5 s16777215 '-*' '+*qlog*' !/usr/local/bin/archive_qmail_qlog $LOGDIRQLOG
    note the missing blank space before 'qlog'.

Patches applied 

The daemontools that we are going to install is the result of the original djb daemontools-0.76 plus the following patches;

  • errno patch
  • The multilog_filesize_limit patch (thanks to Sam Tang), which extends the file log size limit to 100MB (default is 16MB).

  • My multilog-readable_datetime patch, which replaces the timestamp with a human readable datetime. Do not install it if you prefer to stick with the timestamp. Here is what the log lines will look like with the patched daemontools:

    @40000000649b607828223d14 tcpserver: status: 0/200/0
    will be
    2023-06-28 16:17:26.501272173 tcpserver: status: 0/200/0


First of all, let's create the folder which will host qmail, daemontools and ucspi-tcp:

mkdir /var/qmail

In this guide I will assume that all the source packages have been downloaded into the /usr/local/src folder.

cd $SRC
wget https://github.com/sagredo-dev/daemontools/archive/refs/tags/v${DAEMONTOOLS_VER}.tar.gz
tar xzf v${DAEMONTOOLS_VER}.tar.gz

Install daemontools:

cd /var/qmail
mkdir admin
chmod 1755 admin
cd admin
cp -rp ${SRC}/daemontools-${DAEMONTOOLS_VER}/admin/daemontools-${DAEMONTOOLS_VER} .
cd daemontools-${DAEMONTOOLS_VER}
chown -R root:root .

So we have daemontools in /var/qmail/admin/daemontools

Add the "clear" service, so that you can easily clear the readproctitle service errors line:

mkdir -p /var/qmail/supervise/clear
touch /var/qmail/supervise/clear/down

cat > /var/qmail/supervise/clear/run << __EOF__
yes '' | head -4000 | tr '\n' .

chmod +x /var/qmail/supervise/clear/run

Running daemontools at boot time

The command /command/svcscanboot will be added in your /etc/inittab. It will be sufficient to run qmail at boot time.

On systemd based OS the above command has to be added to rc.local in order to be executed at boot time, supposing that rc.local is executed at boot time, or you can choose to create a specific daemontools.service as follows:

cat > /etc/systemd/system/daemontools.service << __EOF__
Description=Daemontools service supervision



systemctl enable daemontools.service
systemctl start  daemontools.service



cd daemontools-​${DAEMONTOOLS_VER}

this line also has same 3 hidden chars 9see in hex)

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Thank you. I retyped those string

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cp -rp ${SRC}/daemontools-${DAEMONTOOLS_VER}/admin/daemontools-​${DAEMONTOOLS_VER} .

this line somehow has 3 hidden bytes (copy it and look in hex) which makes it wrong

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suggestion to insert install of build-essentials etc on this page.

is it an idea to put the following already here instead of on page installing and configuring vpopmail?:

apt install build-essential autoconf automake libmariadb-dev libmariadb-dev-compat

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suggestion to insert install of build-essentials etc on this page.

I created a page with the preinstallation tasks, where this and other preliminary tasks are covered. Fill free to post other hints 

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suggestion to insert install of build-essentials etc on this page.

ok, inserted

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make: not found

Hi everybody .

i had a problem need your help :

- when i run a command line :

# package/install 

i see : 

Linking ./src/* into ./compile...
Compiling everything in ./compile...
package/compile: 20: exec: make: not found . 

help me , pls .


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make: not found

I think that you should install autotools. Please refer to your distribution's documentation for the purpose

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attribute eXecute to "run" file


I´m doing a procedure to install qmail to CentOS 8 (systemd)

run file gets 644 attribute, should we change to 744 ?

Thanks for your work !

Marco Varanda

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attribute eXecute to


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Supervise not running on debian

If you receive error: Error supervise not running
It's because daemontools/svscanboot is not starting from sysvinit inittab.

To start from systemd:

cat > /lib/systemd/system/daemontools.service << __EOF__
Description=Daemontools service supervision

ExecStart=/command/svscanboot /etc/service/


systemctl enable daemontools.service
systemctl status daemontools

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Broken link

qmail.org  is offline, change:

wget http://www.qmail.org/netqmail-1.06.tar.gz


wget https://notes.sagredo.eu/files/qmail/tar/netqmail-1.06.tar.gz

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patch of multilog file size limit


This is the little multilog patch I would like to share.

By default multilog only support max 16MB log file, for my email server, 16MB only can save 5 hours log, so I made this little patch, and change multilog file limit to 100MB, here how to apply:

cd /usr/local/src
wget https://www.phpini.com/files/multilog_filesize_limit.patch
cd /var/qmail/admin/daemontools
patch -p1 < /usr/local/src/multilog_filesize_limit.patch

and then update log/run file/s, now can assign file size to s104857600 (100MB).

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patch of multilog file size limit

thank you, Sam.. I'll add it asap

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patch of multilog file size limit

I have recently installed qmail from all the great information here (thanks for this).  But after reviewing my log files they are all 16M and rotate out after the 10th one (current log and then 9 of the renamed @.....#.s files).  So I did check the multilog.c file from the patch just to confirm and everything looks good there.  But it is still cutting the logs out at 16M instead of 100M.  How do I go about figuring out where to change that value and maybe even increase the number of logs it keeps?

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patch of multilog file size limit

in the log run file you have something like this

  exec /usr/local/bin/setuidgid $LOGUSER /usr/local/bin/multilog t n5 s16777215 $LOGDIR \

where n5 is the number of log files and s16777215 is the maximum size in bytes. Look here for more info http://cr.yp.to/daemontools/multilog.html

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clear service

the creation of clear service is non understandeable and not well described

cat > clear/run < 

syntax error near unexpected token `newline'

what must do run to clear ?

no link creation for service clear

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clear service

thank you, corrected

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But how do you set the PATH so daemontools can run properly?

I tried installing daemontools exactly as outlined above.  But qmailctl start fails because it can't find svc, svok, etc.  I researched on the web, and it appears that the issue is with daemontools not being found in the PATH.  I've tried updating the path in /etc/profile, and in /etc/inittab (when launching svscan).  Although ps -ef | grep svscan demonstrates that svscan is running, qmailctl can't seem to find scripts in the /command folder.

(Per your suggestion, I'm trying to do this install on Slackware  (version 13.37).)

I also tried running ./rts > rts.out (as mentioned in Dave Sill's book, "Life With Qmail") but it bombs on every line--again complaining 'command not found' one line after the next.

What am I doing wrong?

Thanks in advance for your response.

-Dave Martin

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Hi Dave, first of all thanks

Hi Dave, first of all thanks a lot for your support.

You should have this PATH inside the /command/svscanboot script:


qmail should start by means of a line inside /etc/inittab


so, you may want to check that svscanboot was actually launched on boot, or try to run it manually. I prefer to have it in my rc.local

fyi, I have tested everything on a slackware64 13.37

cheers :)


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Daemantools with systemd

if your linux using systemd

remove SV:123456:repawn:/command/svscanboot from /etc/inittab

create a file at /lib/systemd/system/daemontools.service
edit as

Description=DJB daemontools
After=syslog.target network.target



copy links

ln -s /lib/systemd/system/daemontools.service /etc/systemd/system/multi-user.target.wants

reboot ur system

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I confirmed the settings you gave, but still not working

qmailctl start continues to return errors on line 17: svok: command not found 

However, ps -ef | grep svscan returns the following:

root 1886 1 0 Mar10 ? 00:00:00 /bin/sh /command/svscanboot
root 1948 1886 0 Mar10 ? 00:00:02 svscan /service
root 9379 6093 0 01:12 pts/0 00:00:00 grep svscan

Could there be a permissions issue with the qmail user accounts?  Does the qmail group need to be granted permission to in order to run the daemontool utilities?

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It's seems like the

It's seems like the daemontools' installation has failed... can you post please:

ls -l /command/
ps axfuww

anyway feel free to contact me in private using the contact button above

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