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/shared/MurmurHash2.c which is Public Domain
  34         - except src/shared/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, you need the following additional
 144         dependencies:
 145
 146         pkg-config
 147         docbook-xsl
 148         xsltproc
 149         automake
 150         autoconf
 151         libtool
 152         intltool
 153         gperf
 154         python (optional)
 155         python-lxml (optional, but required to build the indices)
 156         sphinx (optional)
 157
 158         When systemd-hostnamed is used, it is strongly recommended to
 159         install nss-myhostname to ensure that, in a world of
 160         dynamically changing hostnames, the hostname stays resolvable
 161         under all circumstances. In fact, systemd-hostnamed will warn
 162         if nss-myhostname is not installed.
 163
 164         To build HTML documentation for python-systemd using sphinx,
 165         please first install systemd (using 'make install'), and then
 166         invoke sphinx-build with 'make sphinx-<target>', with <target>
 167         being 'html' or 'latexpdf'. If using DESTDIR for installation,
 168         pass the same DESTDIR to 'make sphinx-html' invocation.
 169
 170 USERS AND GROUPS:
 171         Default udev rules use the following standard system group
 172         names, which need to be resolvable by getgrnam() at any time,
 173         even in the very early boot stages, where no other databases
 174         and network are available:
 175
 176         audio, cdrom, dialout, disk, input, kmem, lp, tape, tty, video
 177
 178         During runtime, the journal daemon requires the
 179         "systemd-journal" system group to exist. New journal files will
 180         be readable by this group (but not writable), which may be used
 181         to grant specific users read access. In addition, system
 182         groups "wheel" and "adm" will be given read-only access to
 183         journal files using systemd-tmpfiles.service.
 184
 185         The journal gateway daemon requires the
 186         "systemd-journal-gateway" system user and group to
 187         exist. During execution this network facing service will drop
 188         privileges and assume this uid/gid for security reasons.
 189
 190         Similarly, the NTP daemon requires the "systemd-timesync" system
 191         user and group to exist.
 192
 193         Similarly, the network management daemon requires the
 194         "systemd-network" system user and group to exist.
 195
 196         Similarly, the name resolution daemon requires the
 197         "systemd-resolve" system user and group to exist.
 198
 199         Similarly, the kdbus dbus1 proxy daemon requires the
 200         "systemd-bus-proxy" system user and group to exist.
 201
 202 NSS:
 203         systemd ships with three NSS modules:
 204
 205         nss-myhostname resolves the local hostname to locally
 206         configured IP addresses, as well as "localhost" to
 207         127.0.0.1/::1.
 208
 209         nss-resolve enables DNS resolution via the systemd-resolved
 210         DNS/LLMNR caching stub resolver "systemd-resolved".
 211
 212         nss-mymachines enables resolution of all local containers
 213         registered with machined to their respective IP addresses.
 214
 215         To make use of these NSS modules, please add them to the
 216         "hosts: " line in /etc/nsswitch.conf. The "resolve" module
 217         should replace the glibc "dns" module in this file.
 218
 219         The three modules should be used in the following order:
 220
 221                 hosts: files mymachines resolve myhostname
 222
 223 SYSV INIT.D SCRIPTS:
 224         When calling "systemctl enable/disable/is-enabled" on a unit which is a
 225         SysV init.d script, it calls /usr/lib/systemd/systemd-sysv-install;
 226         this needs to translate the action into the distribution specific
 227         mechanism such as chkconfig or update-rc.d. Packagers need to provide
 228         this script if you need this functionality (you don't if you disabled
 229         SysV init support).
 230
 231         Please see src/systemctl/systemd-sysv-install.SKELETON for how this
 232         needs to look like, and provide an implementation at the marked places.
 233
 234 WARNINGS:
 235         systemd will warn you during boot if /etc/mtab is not a
 236         symlink to /proc/mounts. Please ensure that /etc/mtab is a
 237         proper symlink.
 238
 239         systemd will warn you during boot if /usr is on a different
 240         file system than /. While in systemd itself very little will
 241         break if /usr is on a separate partition, many of its
 242         dependencies very likely will break sooner or later in one
 243         form or another. For example, udev rules tend to refer to
 244         binaries in /usr, binaries that link to libraries in /usr or
 245         binaries that refer to data files in /usr. Since these
 246         breakages are not always directly visible, systemd will warn
 247         about this, since this kind of file system setup is not really
 248         supported anymore by the basic set of Linux OS components.
 249
 250         systemd requires that the /run mount point exists. systemd also
 251         requires that /var/run is a symlink to /run.
 252
 253         For more information on this issue consult
 254         http://freedesktop.org/wiki/Software/systemd/separate-usr-is-broken
 255
 256         To run systemd under valgrind, compile with VALGRIND defined
 257         (e.g. ./configure CPPFLAGS='... -DVALGRIND=1'). Otherwise,
 258         false positives will be triggered by code which violates
 259         some rules but is actually safe.
 260
 261 ENGINEERING AND CONSULTING SERVICES:
 262         ENDOCODE <https://endocode.com/> offers professional
 263         engineering and consulting services for systemd. Please
 264         contact Chris Kühl <chris@endocode.com> for more information.