SMLinux Guide

1. Intro

SMLinux is an experimental linux distribution based on the musl C library using a Slackware-based build/packaging system, aimed at intermediate and advanced users. In some packages, SMLinux uses patches from some of the below listed linux distributions for bug fixing, better support and consistency with the musl C library.

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2. Acknowledgements and Credits

The HUGE THANKS to:

People of:

Slackware Linux

Alpine Linux

Adelie Linux

Sabotage Linux

Openwrt Embedded Linux

Gentoo Linux

Musl C Library

Including Individuals:

Laurent "skarnet" Bercot for his GCC compiers and toolchains

B. Watson "Urchlay" for his substantial assistance in the overall build environment, ideas, suggestions and testing

And many many more unnamed people (and in some cases, people who chose not to be named) on the internet.

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3. Support

Kindly join the #smlinux channel on web.libera.chat from your IRC client. In case you don't have an IRC client, you can use libera network's webchat interface to connect to us.

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4. Features

• Uses busybox runit as the default init system
• Low on system resources
• Improved service management using runit's sv
• Uses Slackware Linux's pkgtools for package management
• Refined build and packaging system derived from Slackware's build scripts and ideas

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5. System Requirements

• An x86_64 Intel/AMD machine for the x86_64 port
• Minimum 4GB HDD/SSD/memory card/flash drive storage space

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6. Getting it

6.1. Git Development

You can visit http://git.pktsurf.in/smlinux for the latest developments.

Additionally you can clone the git repo by running:

# git clone http://git.pktsurf.in/smlinux

6.2. Source Code

You can download the complete source code by running

# rsync -Pa pktsurf.in::smlinux/smlinux-1.0/source .

Please note the "." at the end where the "source" directory will be downloaded into.

7. Installation

All SMLinux images can be used for offline/standalone installation. No pre-installation network setup is required. After downloading, decompress using the unzip utility. Both x86_64 and raspberry pi images can be dd'd onto a flash drive/memory card respectively depending on device. This entire section assumes that /dev/sdb is your target storage device.

7.1. x86_64

The x86_64 image also has two partitions with the above partition layout. However, this image comes with a separate package directory /root/packages containing the packages that can be installed onto the target system. dd the x86_64 image to a flash drive of a size 4GB or larger:

# dd if=smlinux-x86_64-1.0.img of=/dev/sdb

Boot up the target system, select "Boot from USB" or equivalent BIOS boot up option for flash drives. Once SMLinux is initialized, at the end of the boot, at the tty1 login,

Username: root

Password: smlinux

Partition the target storage drive using a tool of your choice. Typical layout is as follows:

• If using syslinux, you need two partitions:

/boot to be formatted as an FAT32 partition and, / to be formatted as any journalling partition

Then format the partitions, assuming /dev/sdb is your hard disk/SSD

# mkfs.fat /dev/sdb1

# mkfs.ext4 /dev/sdb2

Creation and formatting of RAID partitions or encryption partitions is beyond the scope of this guide

The following instructions assume /dev/sdb is your target storage device:

# mkdir -p /mnt/boot 
# mount /dev/sdb1 /mnt/boot
# mount /dev/sdb2 /mnt

The installer packages for the target rootfs are available in /root/packages/x86_64 of the SMLinux boot drive. Install them using installpkg

# cd /root/packages/x86_64 
# installpkg --root /mnt */*

Install the bootloader on /dev/sdb:

# dd if=/lib/syslinux/bios/mbr.bin of=/dev/sdb

If you use syslinux, assuming you have TWO partitions, one FAT for /boot and one journalling partition for /
# syslinux -i /dev/sdb1  OR

If you use extlinux, assuming you have on ONE journalling partition, like ext4 for /
# extlinux -i /dev/sdb1 

The bootloader configuration files -

for extlinux: /mnt/boot/extlinux.conf,

for syslinux: /mnt/boot/syslinux.conf

Modify /mnt/fstab by adding the root partition (and optionally the /boot partition if you have made a separate FAT32 boot partition). Unmount /mnt/{boot} and reboot. Unplug the flash drive before BIOS POST.

7.2 Post-Install Tasks

After a reboot, login when presented with a tty1 prompt:

Username: root

Password: smlinux

Additional network setup for x86_64:

This section assumes that the system has eth0 network interface.

To setup hostname for the current session, run

# hostname example.com

Edit /etc/hostname with your choice to set it permanently.

DHCP

dhclient is a wrapper around busybox udhcpc DHCP client. Run

# dhclient eth0

to get a DHCP lease.

Static IP

Use the ifconfig/route from the old net utils package or the new ip from the iproute2 package:

# ifconfig eth0 192.168.0.2 netmask 255.255.255.0
# route add default gw 192.168.0.1
# ifconfig eth0 up

Newer method using ip from busybox/iproute2 packages

# ip addr add 192.168.0.2/24 dev eth0
# ip route add default via 192.168.0.1
# ip link set eth0 up

Add your DNS servers to /etc/resolv.conf.

Verify connectivity:

# ping google.com

Add your preferred method to /etc/rc.d/rc.local.

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8. System Administration

8.1. SMLinux Boot Order Overview

kernel
  |
init (busybox runit)
  |
/etc/inittab
  |
/etc/rc.d/rc.start
  |
/etc/rc.d/rc.{modules,initialnet,gtk}
  |
/var/service/{ssh,dnsmasq,sysklogd...}

8.2. Timezones

The default timezone set is UTC. You can change timezones in two ways: by creating a symlink and/or by setting the TZ variable:

# ln -sf /share/zoneinfo/Asia/Kolkata /etc/localtime

And/or add export TZ="Asia/Kolkata" to /etc/profile.

8.3. Runit

SMLinux uses the runit init system from the busybox binary. Service run files are placed inside /var/service, which is a symlink to /etc/service. If a service directory has a down file, that service won't be run automatically at bootup. Every service file has a run file with the executable bit set, that may declare variables and paths relating to the execution of the service. Once run, runit automatically creates a supervise directory that contains the program PID, lock file, service status, etcetera owned by root. The prerequisite for running a service file is that the service should support foregrounding and optionally should have the ability to write to syslog. Examples:

To start a service,

# sv u dnsmasq OR 
# sv start dnsmasq

To stop a service,

# sv d dnsmasq OR 
# sv stop dnsmasq

To restart,

# sv restart dnsmasq

To check the status of the service,

# sv status dnsmasq OR
# sv s dnsmasq

To check the status of all the services,

# sv s /var/service/*

For more information, run man sv.

8.4 System Time and NTP

Run the date command to set the correct time and date. Example:

# date -s "2020-01-01 12:00:00"

Optionally NTP may be used for keeping the clock more accurate.

8.5 Logging

The default logging utility is sysklogd. System logs can be found in /var/log. Sysklogd configuration can be found in /etc/syslog.conf. Modify the configuration file and restart the service:

# sv restart syslogd

Logrotate is run at regular intervals along with (d)cron for sanitization of the /var/log directory.

8.6 Filesystem Layout

SMLinux does not follow the File System Hierarchy(FHS) standard and instead uses clever symlink hacks used by Sabotage Linux:

/usr -> symlink to /

/sbin -> symlink to /bin

The above symlinking hack gets rid of age-old issue relating to paths being hard-coded into scripts and some of those scripts failing to run as a result.

8.7 Package Management

Package management is identical to that of Slackware. Packages can be installed/removed/upgraded using pkgtools utilities.. .tbz, .tlz, .tgz and .txz extensions are supported.

Some examples:

To install a package,

# installpkg /path/to/<package.tlz>

To install a package to specific directory,

# installpkg --root /path/to/directory /path/to/<package.tlz>

To upgrade a package,

# upgradepkg /path/to/<package.tlz>

To remove a package,

# removepkg <package>

To forcefully remove a package,

# removepkg /var/log/packages/<package>

To find which installed file belongs to which package,

# grep -H <file> /var/log/packages/*

8.8 User and Group Management

Busybox utilities are used for user and group management. Some examples:

To add a group "ftp" with UID 2000,

# addgroup -g 2000 ftp

To add a user "example" and allocate a home directory, a bash shell and add him to the "ftp" group and a UID of 1050,

# adduser -h /home/example -u 1050 -s /bin/bash -G ftp example

To remove a user "example" along with his home directory,

# deluser --remove-home example

To remove "example" user from group "ftp",

# deluser example ftp

To remove the ftp group itself,

# delgroup ftp