README

   1 systemd System and Service Manager
   2
   3 DETAILS:
   4         http://0pointer.de/blog/projects/systemd.html
   5
   6 WEB SITE:
   7         http://www.freedesktop.org/wiki/Software/systemd
   8
   9 GIT:
  10         git@github.com:systemd/systemd.git
  11         https://github.com/systemd/systemd.git
  12
  13 GITWEB:
  14         https://github.com/systemd/systemd
  15
  16 MAILING LIST:
  17         http://lists.freedesktop.org/mailman/listinfo/systemd-devel
  18         http://lists.freedesktop.org/mailman/listinfo/systemd-commits
  19
  20 IRC:
  21         #systemd on irc.freenode.org
  22
  23 BUG REPORTS:
  24         https://github.com/systemd/systemd/issues
  25
  26 AUTHOR:
  27         Lennart Poettering
  28         Kay Sievers
  29         ...and many others
  30
  31 LICENSE:
  32         LGPLv2.1+ for all code
  33         - except src/basic/MurmurHash2.c which is Public Domain
  34         - except src/basic/siphash24.c which is CC0 Public Domain
  35         - except src/journal/lookup3.c which is Public Domain
  36         - except src/udev/* which is (currently still) GPLv2, GPLv2+
  37
  38 REQUIREMENTS:
  39         Linux kernel >= 3.7
  40         Linux kernel >= 3.8 for Smack support
  41
  42         Kernel Config Options:
  43           CONFIG_DEVTMPFS
  44           CONFIG_CGROUPS (it is OK to disable all controllers)
  45           CONFIG_INOTIFY_USER
  46           CONFIG_SIGNALFD
  47           CONFIG_TIMERFD
  48           CONFIG_EPOLL
  49           CONFIG_NET
  50           CONFIG_SYSFS
  51           CONFIG_PROC_FS
  52           CONFIG_FHANDLE (libudev, mount and bind mount handling)
  53
  54         udev will fail to work with the legacy sysfs layout:
  55           CONFIG_SYSFS_DEPRECATED=n
  56
  57         Legacy hotplug slows down the system and confuses udev:
  58           CONFIG_UEVENT_HELPER_PATH=""
  59
  60         Userspace firmware loading is not supported and should
  61         be disabled in the kernel:
  62           CONFIG_FW_LOADER_USER_HELPER=n
  63
  64         Some udev rules and virtualization detection relies on it:
  65           CONFIG_DMIID
  66
  67         Support for some SCSI devices serial number retrieval, to
  68         create additional symlinks in /dev/disk/ and /dev/tape:
  69           CONFIG_BLK_DEV_BSG
  70
  71         Required for PrivateNetwork and PrivateDevices in service units:
  72           CONFIG_NET_NS
  73           CONFIG_DEVPTS_MULTIPLE_INSTANCES
  74         Note that systemd-localed.service and other systemd units use
  75         PrivateNetwork and PrivateDevices so this is effectively required.
  76
  77         Optional but strongly recommended:
  78           CONFIG_IPV6
  79           CONFIG_AUTOFS4_FS
  80           CONFIG_TMPFS_XATTR
  81           CONFIG_{TMPFS,EXT4,XFS,BTRFS_FS,...}_POSIX_ACL
  82           CONFIG_SECCOMP
  83           CONFIG_CHECKPOINT_RESTORE (for the kcmp() syscall)
  84
  85         Required for CPUShares in resource control unit settings
  86           CONFIG_CGROUP_SCHED
  87           CONFIG_FAIR_GROUP_SCHED
  88
  89         Required for CPUQuota in resource control unit settings
  90           CONFIG_CFS_BANDWIDTH
  91
  92         For systemd-bootchart, several proc debug interfaces are required:
  93           CONFIG_SCHEDSTATS
  94           CONFIG_SCHED_DEBUG
  95
  96         For UEFI systems:
  97           CONFIG_EFIVAR_FS
  98           CONFIG_EFI_PARTITION
  99
 100         Note that kernel auditing is broken when used with systemd's
 101         container code. When using systemd in conjunction with
 102         containers, please make sure to either turn off auditing at
 103         runtime using the kernel command line option "audit=0", or
 104         turn it off at kernel compile time using:
 105           CONFIG_AUDIT=n
 106         If systemd is compiled with libseccomp support on
 107         architectures which do not use socketcall() and where seccomp
 108         is supported (this effectively means x86-64 and ARM, but
 109         excludes 32-bit x86!), then nspawn will now install a
 110         work-around seccomp filter that makes containers boot even
 111         with audit being enabled. This works correctly only on kernels
 112         3.14 and newer though. TL;DR: turn audit off, still.
 113
 114         glibc >= 2.16
 115         libcap
 116         libmount >= 2.20 (from util-linux)
 117         libseccomp >= 1.0.0 (optional)
 118         libblkid >= 2.24 (from util-linux) (optional)
 119         libkmod >= 15 (optional)
 120         PAM >= 1.1.2 (optional)
 121         libcryptsetup (optional)
 122         libaudit (optional)
 123         libacl (optional)
 124         libselinux (optional)
 125         liblzma (optional)
 126         liblz4 >= 119 (optional)
 127         libgcrypt (optional)
 128         libqrencode (optional)
 129         libmicrohttpd (optional)
 130         libpython (optional)
 131         libidn (optional)
 132         elfutils >= 158 (optional)
 133         make, gcc, and similar tools
 134
 135         During runtime, you need the following additional
 136         dependencies:
 137
 138         util-linux >= v2.26 required
 139         dbus >= 1.4.0 (strictly speaking optional, but recommended)
 140         dracut (optional)
 141         PolicyKit (optional)
 142
 143         When building from git, the following tools are needed:
 144
 145         pkg-config
 146         docbook-xsl
 147         xsltproc
 148         automake
 149         autoconf
 150         libtool
 151         intltool
 152         gperf
 153         python (optional)
 154         python-lxml (optional, but required to build the indices)
 155         sphinx (optional)
 156
 157         The build system is initialized with ./autogen.sh. A tar ball
 158         can be created with:
 159           git archive --format=tar --prefix=systemd-222/ v222 | xz > systemd-222.tar.xz
 160
 161         When systemd-hostnamed is used, it is strongly recommended to
 162         install nss-myhostname to ensure that, in a world of
 163         dynamically changing hostnames, the hostname stays resolvable
 164         under all circumstances. In fact, systemd-hostnamed will warn
 165         if nss-myhostname is not installed.
 166
 167         To build HTML documentation for python-systemd using sphinx,
 168         please first install systemd (using 'make install'), and then
 169         invoke sphinx-build with 'make sphinx-<target>', with <target>
 170         being 'html' or 'latexpdf'. If using DESTDIR for installation,
 171         pass the same DESTDIR to 'make sphinx-html' invocation.
 172
 173 USERS AND GROUPS:
 174         Default udev rules use the following standard system group
 175         names, which need to be resolvable by getgrnam() at any time,
 176         even in the very early boot stages, where no other databases
 177         and network are available:
 178
 179         audio, cdrom, dialout, disk, input, kmem, lp, tape, tty, video
 180
 181         During runtime, the journal daemon requires the
 182         "systemd-journal" system group to exist. New journal files will
 183         be readable by this group (but not writable), which may be used
 184         to grant specific users read access. In addition, system
 185         groups "wheel" and "adm" will be given read-only access to
 186         journal files using systemd-tmpfiles.service.
 187
 188         The journal gateway daemon requires the
 189         "systemd-journal-gateway" system user and group to
 190         exist. During execution this network facing service will drop
 191         privileges and assume this uid/gid for security reasons.
 192
 193         Similarly, the NTP daemon requires the "systemd-timesync" system
 194         user and group to exist.
 195
 196         Similarly, the network management daemon requires the
 197         "systemd-network" system user and group to exist.
 198
 199         Similarly, the name resolution daemon requires the
 200         "systemd-resolve" system user and group to exist.
 201
 202         Similarly, the kdbus dbus1 proxy daemon requires the
 203         "systemd-bus-proxy" system user and group to exist.
 204
 205 NSS:
 206         systemd ships with three NSS modules:
 207
 208         nss-myhostname resolves the local hostname to locally
 209         configured IP addresses, as well as "localhost" to
 210         127.0.0.1/::1.
 211
 212         nss-resolve enables DNS resolution via the systemd-resolved
 213         DNS/LLMNR caching stub resolver "systemd-resolved".
 214
 215         nss-mymachines enables resolution of all local containers
 216         registered with machined to their respective IP addresses.
 217
 218         To make use of these NSS modules, please add them to the
 219         "hosts: " line in /etc/nsswitch.conf. The "resolve" module
 220         should replace the glibc "dns" module in this file.
 221
 222         The three modules should be used in the following order:
 223
 224                 hosts: files mymachines resolve myhostname
 225
 226 SYSV INIT.D SCRIPTS:
 227         When calling "systemctl enable/disable/is-enabled" on a unit which is a
 228         SysV init.d script, it calls /usr/lib/systemd/systemd-sysv-install;
 229         this needs to translate the action into the distribution specific
 230         mechanism such as chkconfig or update-rc.d. Packagers need to provide
 231         this script if you need this functionality (you don't if you disabled
 232         SysV init support).
 233
 234         Please see src/systemctl/systemd-sysv-install.SKELETON for how this
 235         needs to look like, and provide an implementation at the marked places.
 236
 237 WARNINGS:
 238         systemd will warn you during boot if /etc/mtab is not a
 239         symlink to /proc/mounts. Please ensure that /etc/mtab is a
 240         proper symlink.
 241
 242         systemd will warn you during boot if /usr is on a different
 243         file system than /. While in systemd itself very little will
 244         break if /usr is on a separate partition, many of its
 245         dependencies very likely will break sooner or later in one
 246         form or another. For example, udev rules tend to refer to
 247         binaries in /usr, binaries that link to libraries in /usr or
 248         binaries that refer to data files in /usr. Since these
 249         breakages are not always directly visible, systemd will warn
 250         about this, since this kind of file system setup is not really
 251         supported anymore by the basic set of Linux OS components.
 252
 253         systemd requires that the /run mount point exists. systemd also
 254         requires that /var/run is a symlink to /run.
 255
 256         For more information on this issue consult
 257         http://freedesktop.org/wiki/Software/systemd/separate-usr-is-broken
 258
 259         To run systemd under valgrind, compile with VALGRIND defined
 260         (e.g. ./configure CPPFLAGS='... -DVALGRIND=1'). Otherwise,
 261         false positives will be triggered by code which violates
 262         some rules but is actually safe.
 263
 264 ENGINEERING AND CONSULTING SERVICES:
 265         ENDOCODE <https://endocode.com/> offers professional
 266         engineering and consulting services for systemd. Please
 267         contact Chris Kühl <chris@endocode.com> for more information.