{
    "mode": "man",
    "parameter": "kernel-command-line",
    "section": "7",
    "url": "https://www.chedong.com/phpMan.php/man/kernel-command-line/7/json",
    "generated": "2026-10-04T14:20:19Z",
    "synopsis": "/proc/cmdline",
    "sections": {
        "NAME": {
            "content": "kernel-command-line - Kernel command line parameters\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "/proc/cmdline\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "The kernel, the programs running in the initrd and in the host system may be configured at\nboot via kernel command line arguments. In addition, various systemd tools look at the EFI\nvariable \"SystemdOptions\" (if available). Both sources are combined, but the kernel command\nline has higher priority. Please note that the EFI variable is only used by systemd tools,\nand is ignored by the kernel and other user space tools, so it is not a replacement for the\nkernel command line.\n\nFor command line parameters understood by the kernel, please see kernel-parameters.html[1]\nand bootparam(7).\n\nFor command line parameters understood by the initrd, see dracut.cmdline(7), or the\ndocumentation of the specific initrd implementation of your installation.\n",
            "subsections": []
        },
        "CORE OS COMMAND LINE ARGUMENTS": {
            "content": "systemd.unit=, rd.systemd.unit=, systemd.dumpcore, systemd.crashchvt, systemd.crashshell,\nsystemd.crashreboot, systemd.confirmspawn, systemd.servicewatchdogs, systemd.showstatus,\nsystemd.statusunitformat=, systemd.logtarget=, systemd.loglevel=, systemd.loglocation=,\nsystemd.logcolor, systemd.logratelimitkmsg, systemd.defaultstandardoutput=,\nsystemd.defaultstandarderror=, systemd.setenv=, systemd.machineid=,\nsystemd.setcredential=, systemd.setcredentialbinary=, systemd.importcredentials=,\nsystemd.reloadlimitintervalsec=, systemd.reloadlimitburst=\nParameters understood by the system and service manager to control system behavior. For\ndetails, see systemd(1).\n\nAdded in version 186.\n\nsystemd.mask=, systemd.wants=, systemd.debugshell\nAdditional parameters understood by systemd-debug-generator(8), to mask or start specific\nunits at boot, or invoke a debug shell on tty9.\n\nAdded in version 215.\n\nsystemd.run=, systemd.runsuccessaction=, systemd.runfailureaction=\nAdditional parameters understood by systemd-run-generator(8), to run a command line\nspecified on the kernel command line as system service after booting up.\n\nAdded in version 240.\n\nsystemd.earlycorepattern=\nDuring early boot, the generation of core dump files is disabled until a core dump\nhandler (if any) takes over. This parameter allows specifying an absolute path where core\ndump files should be stored until a handler is installed. The path should be absolute and\nmay contain specifiers, see core(5) for details.\n\nAdded in version 240.\n\nsystemd.restorestate=\nThis parameter is understood by several system tools to control whether or not they\nshould restore system state from the previous boot. For details, see systemd-\nbacklight@.service(8) and systemd-rfkill.service(8).\n\nAdded in version 209.\n\nsystemd.volatile=\nThis parameter controls whether the system shall boot up in volatile mode. Takes a\nboolean argument, or the special value \"state\". If false (the default), normal boot mode\nis selected, the root directory and /var/ are mounted as specified on the kernel command\nline or /etc/fstab, or otherwise configured. If true, full state-less boot mode is\nselected. In this case the root directory is mounted as volatile memory file system\n(\"tmpfs\"), and only /usr/ is mounted from the file system configured as root device, in\nread-only mode. This enables fully state-less boots were the vendor-supplied OS is used\nas shipped, with only default configuration and no stored state in effect, as /etc/ and\n/var/ (as well as all other resources shipped in the root file system) are reset at boot\nand lost on shutdown. If this setting is set to \"state\" the root file system is mounted\nread-only, however /var/ is mounted as a volatile memory file system (\"tmpfs\"), so that\nthe system boots up with the normal configuration applied, but all state reset at boot\nand lost at shutdown. If this setting is set to \"overlay\" the root file system is set up\nas \"overlayfs\" mount combining the read-only root directory with a writable \"tmpfs\", so\nthat no modifications are made to disk, but the file system may be modified nonetheless\nwith all changes being lost at reboot. For details, see systemd-volatile-root.service(8)\nand systemd-fstab-generator(8).\n\nAdded in version 233.\n\nquiet\nParameter understood by both the kernel and the system and service manager to control\nconsole log verbosity. For details, see systemd(1).\n\nAdded in version 186.\n\ndebug\nParameter understood by both the kernel and the system and service manager to control\nconsole log verbosity. For details, see systemd(1).\n\nAdded in version 205.\n\n-b, rd.emergency, emergency, rd.rescue, rescue, single, s, S, 1, 2, 3, 4, 5\nParameters understood by the system and service manager, as compatibility and convenience\noptions. For details, see systemd(1).\n\nAdded in version 186.\n\nlocale.LANG=, locale.LANGUAGE=, locale.LCCTYPE=, locale.LCNUMERIC=, locale.LCTIME=,\nlocale.LCCOLLATE=, locale.LCMONETARY=, locale.LCMESSAGES=, locale.LCPAPER=,\nlocale.LCNAME=, locale.LCADDRESS=, locale.LCTELEPHONE=, locale.LCMEASUREMENT=,\nlocale.LCIDENTIFICATION=\nParameters understood by the system and service manager to control locale and language\nsettings. For details, see systemd(1).\n\nAdded in version 186.\n\nfsck.mode=, fsck.repair=\nParameters understood by the file system checker services. For details, see systemd-\nfsck@.service(8).\n\nAdded in version 186.\n\nquotacheck.mode=\nParameter understood by the file quota checker service. For details, see systemd-\nquotacheck.service(8).\n\nAdded in version 186.\n\nsystemd.journald.forwardtosyslog=, systemd.journald.forwardtokmsg=,\nsystemd.journald.forwardtoconsole=, systemd.journald.forwardtowall=\nParameters understood by the journal service. For details, see systemd-\njournald.service(8).\n\nAdded in version 186.\n\nvconsole.keymap=, vconsole.keymaptoggle=, vconsole.font=, vconsole.fontmap=,\nvconsole.fontunimap=\nParameters understood by the virtual console setup logic. For details, see\nvconsole.conf(5).\n\nAdded in version 186.\n\nudev.loglevel=, rd.udev.loglevel=, udev.childrenmax=, rd.udev.childrenmax=,\nudev.execdelay=, rd.udev.execdelay=, udev.eventtimeout=, rd.udev.eventtimeout=,\nudev.timeoutsignal=, rd.udev.timeoutsignal=, udev.blockdevreadonly,\nrd.udev.blockdevreadonly, net.ifnames=, net.naming-scheme=\nParameters understood by the device event managing daemon. For details, see systemd-\nudevd.service(8).\n\nAdded in version 186.\n\nplymouth.enable=\nMay be used to disable the Plymouth boot splash. For details, see plymouth(8).\n\nAdded in version 186.\n\nluks=, rd.luks=, luks.crypttab=, rd.luks.crypttab=, luks.name=, rd.luks.name=, luks.uuid=,\nrd.luks.uuid=, luks.options=, rd.luks.options=, luks.key=, rd.luks.key=\nConfigures the LUKS full-disk encryption logic at boot. For details, see systemd-\ncryptsetup-generator(8).\n\nAdded in version 186.\n\nfstab=, rd.fstab=\nConfigures the /etc/fstab logic at boot. For details, see systemd-fstab-generator(8).\n\nAdded in version 186.\n\nroot=, rootfstype=, rootflags=, ro, rw\nConfigures the root file system and its file system type and mount options, as well as\nwhether it shall be mounted read-only or read-write initially. For details, see systemd-\nfstab-generator(8).\n\nIf root= is not set (or set to \"gpt-auto\") the automatic root partition discovery\nimplemented by systemd-gpt-auto-generator(8) will be in effect. In this case rootfstype=,\nrootflags=, ro, rw will be interpreted by systemd-gpt-auto-generator.\n\nAdded in version 215.\n\nmount.usr=, mount.usrfstype=, mount.usrflags=\nConfigures the /usr file system (if required) and its file system type and mount options.\nFor details, see systemd-fstab-generator(8).\n\nAdded in version 235.\n\nveritytab=, rd.veritytab=, roothash=, systemd.verity=, rd.systemd.verity=,\nsystemd.verityrootdata=, systemd.verityroothash=, systemd.verity.rootoptions=, usrhash=,\nsystemd.verityusrdata=, systemd.verityusrhash=, systemd.verityusroptions=\nConfigures the integrity protection root hash for the root and /usr file systems, and\nother related parameters. For details, see systemd-veritysetup-generator(8).\n\nAdded in version 233.\n\nsystemd.gettyauto=\nConfigures whether the serial-getty@.service will run. For details, see systemd-getty-\ngenerator(8).\n\nAdded in version 250.\n\nsystemd.gptauto=, rd.systemd.gptauto=\nConfigures whether GPT-based partition auto-discovery shall be attempted. For details,\nsee systemd-gpt-auto-generator(8).\n\nAdded in version 215.\n\nsystemd.imagepolicy=, rd.systemd.imagepolicy=\nWhen GPT-based partition auto-discovery is used, configures the image dissection policy\nstring to apply, as per systemd.image-policy(7). For details see systemd-gpt-auto-\ngenerator(8).\n\nAdded in version 254.\n\nsystemd.defaulttimeoutstartsec=\nOverrides the default start job timeout DefaultTimeoutStartSec= at boot. For details, see\nsystemd-system.conf(5).\n\nAdded in version 230.\n\nsystemd.defaultdevicetimeoutsec=\nOverrides the default device timeout DefaultDeviceTimeoutSec= at boot. For details, see\nsystemd-system.conf(5).\n\nAdded in version 254.\n\nsystemd.watchdogdevice=\nOverrides the watchdog device path WatchdogDevice=. For details, see systemd-\nsystem.conf(5).\n\nAdded in version 236.\n\nsystemd.watchdogsec=\nOverrides the watchdog timeout settings otherwise configured with RuntimeWatchdog=,\nRebootWatchdog= and KExecWatchdogSec=. Takes a time value (if no unit is specified,\nseconds is the implicitly assumed time unit) or the special strings \"off\" or \"default\".\nFor details, see systemd-system.conf(5).\n\nAdded in version 250.\n\nsystemd.watchdogpresec=\nOverrides the watchdog pre-timeout settings otherwise configured with\nRuntimeWatchdogPreSec=. Takes a time value (if no unit is specified, seconds is the\nimplicitly assumed time unit) or the special strings \"off\" or \"default\". For details, see\nsystemd-system.conf(5).\n\nAdded in version 251.\n\nsystemd.watchdogpretimeoutgovernor=\nOverrides the watchdog pre-timeout settings otherwise configured with\nRuntimeWatchdogPreGovernor=. Takes a string value. For details, see systemd-\nsystem.conf(5).\n\nAdded in version 251.\n\nsystemd.cpuaffinity=\nOverrides the CPU affinity mask for the service manager and the default for all child\nprocesses it forks. This takes precedence over CPUAffinity=, see systemd-system.conf(5)\nfor details.\n\nAdded in version 245.\n\nmodulesload=, rd.modulesload=\nLoad a specific kernel module early at boot. For details, see systemd-modules-\nload.service(8).\n\nAdded in version 187.\n\nnameserver=, domain=\nConfigures DNS server information and search domains, see systemd-resolved.service(8) for\ndetails.\n\nAdded in version 253.\n\nresume=, resumeflags=\nEnables resume from hibernation using the specified device and mount options. All\nfstab(5)-like paths are supported. For details, see systemd-hibernate-resume-\ngenerator(8).\n\nAdded in version 217.\n\nsystemd.firstboot=\nTakes a boolean argument, defaults to on. If off, systemd-firstboot.service(8) will not\nquery the user for basic system settings, even if the system boots up for the first time\nand the relevant settings are not initialized yet. Not to be confused with\nsystemd.condition-first-boot= (see below), which overrides the result of the\nConditionFirstBoot= unit file condition, and thus controls more than just\nsystemd-firstboot.service behaviour.\n\nAdded in version 233.\n\nsystemd.condition-needs-update=\nTakes a boolean argument. If specified, overrides the result of ConditionNeedsUpdate=\nunit condition checks. See systemd.unit(5) for details.\n\nAdded in version 246.\n\nsystemd.condition-first-boot=\nTakes a boolean argument. If specified, overrides the result of ConditionFirstBoot= unit\ncondition checks. See systemd.unit(5) for details. Not to be confused with\nsystemd.firstboot= which only controls behaviour of the systemd-firstboot.service system\nservice but has no effect on the condition check (see above).\n\nAdded in version 246.\n\nsystemd.clock-usec=\nTakes a decimal, numeric timestamp in μs since January 1st 1970, 00:00am, to set the\nsystem clock to. The system time is set to the specified timestamp early during boot. It\nis not propagated to the hardware clock (RTC).\n\nAdded in version 246.\n\nsystemd.random-seed=\nTakes a base64 encoded random seed value to credit with full entropy to the kernel's\nrandom pool during early service manager initialization. This option is useful in testing\nenvironments where delays due to random pool initialization in entropy starved virtual\nmachines shall be avoided.\n\nNote that if this option is used the seed is accessible to unprivileged programs from\n/proc/cmdline. This option is hence a security risk when used outside of test systems,\nsince the (possibly) only seed used for initialization of the kernel's entropy pool might\nbe easily acquired by unprivileged programs.\n\nIt is recommended to pass 512 bytes of randomized data (as that matches the Linux kernel\npool size), which may be generated with a command like the following:\n\ndd if=/dev/urandom bs=512 count=1 status=none | base64 -w 0\n\nAgain: do not use this option outside of testing environments, it's a security risk\nelsewhere, as secret key material derived from the entropy pool can possibly be\nreconstructed by unprivileged programs.\n\nAdded in version 246.\n\nsystemd.hostname=\nAccepts a hostname to set during early boot. If specified takes precedence over what is\nset in /etc/hostname. Note that this does not bar later runtime changes to the hostname,\nit simply controls the initial hostname set during early boot.\n\nAdded in version 246.\n\nsystemd.tty.term.tty=, systemd.tty.rows.tty=, systemd.tty.columns.tty=\nThese arguments allow configuring default values for $TERM, TTYRows=, and TTYColumns= for\ntty tty. Additionally, systemd.tty.term.console will configure the $TERM value used by\nsystemd if not set explicitly using TERM on the kernel command line. The tty name should\nbe specified without the /dev/ prefix (e.g.  \"systemd.tty.rows.ttyS0=80\").\n\nAdded in version 254.\n",
            "subsections": []
        },
        "HISTORY": {
            "content": "systemd 252\nKernel command-line arguments systemd.unifiedcgrouphierarchy and\nsystemd.legacysystemdcgroupcontroller were deprecated. Please switch to the unified\ncgroup hierarchy.\n\nAdded in version 252.\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "systemd(1), systemd-system.conf(5), bootparam(7), systemd.system-credentials(7) smbios-\ntype-11(7), dracut.cmdline(7), systemd-debug-generator(8), systemd-fsck@.service(8), systemd-\nquotacheck.service(8), systemd-journald.service(8), systemd-vconsole-setup.service(8),\nsystemd-udevd.service(8), plymouth(8), systemd-cryptsetup-generator(8), systemd-veritysetup-\ngenerator(8), systemd-fstab-generator(8), systemd-getty-generator(8), systemd-gpt-auto-\ngenerator(8), systemd-volatile-root.service(8), systemd-modules-load.service(8), systemd-\nbacklight@.service(8), systemd-rfkill.service(8), systemd-hibernate-resume-generator(8),\nsystemd-firstboot.service(8), bootctl(1)\n",
            "subsections": []
        },
        "NOTES": {
            "content": "1. kernel-parameters.html\nhttps://docs.kernel.org/admin-guide/kernel-parameters.html\n\nsystemd 255                                                                   KERNEL-COMMAND-LINE(7)",
            "subsections": []
        }
    },
    "summary": "kernel-command-line - Kernel command line parameters",
    "flags": [],
    "examples": [],
    "see_also": [
        {
            "name": "systemd",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/systemd/1/json"
        },
        {
            "name": "systemd-system.conf",
            "section": "5",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-system.conf/5/json"
        },
        {
            "name": "bootparam",
            "section": "7",
            "url": "https://www.chedong.com/phpMan.php/man/bootparam/7/json"
        },
        {
            "name": "systemd.system-credentials",
            "section": "7",
            "url": "https://www.chedong.com/phpMan.php/man/systemd.system-credentials/7/json"
        },
        {
            "name": "type-11",
            "section": "7",
            "url": "https://www.chedong.com/phpMan.php/man/type-11/7/json"
        },
        {
            "name": "dracut.cmdline",
            "section": "7",
            "url": "https://www.chedong.com/phpMan.php/man/dracut.cmdline/7/json"
        },
        {
            "name": "systemd-debug-generator",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-debug-generator/8/json"
        },
        {
            "name": ".service",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/.service/8/json"
        },
        {
            "name": "quotacheck.service",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/quotacheck.service/8/json"
        },
        {
            "name": "systemd-journald.service",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-journald.service/8/json"
        },
        {
            "name": "systemd-vconsole-setup.service",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-vconsole-setup.service/8/json"
        },
        {
            "name": "systemd-udevd.service",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-udevd.service/8/json"
        },
        {
            "name": "plymouth",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/plymouth/8/json"
        },
        {
            "name": "systemd-cryptsetup-generator",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-cryptsetup-generator/8/json"
        },
        {
            "name": "generator",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/generator/8/json"
        },
        {
            "name": "systemd-fstab-generator",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-fstab-generator/8/json"
        },
        {
            "name": "systemd-getty-generator",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-getty-generator/8/json"
        },
        {
            "name": "generator",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/generator/8/json"
        },
        {
            "name": "systemd-volatile-root.service",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-volatile-root.service/8/json"
        },
        {
            "name": "systemd-modules-load.service",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-modules-load.service/8/json"
        },
        {
            "name": ".service",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/.service/8/json"
        },
        {
            "name": "systemd-rfkill.service",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-rfkill.service/8/json"
        },
        {
            "name": "systemd-hibernate-resume-generator",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-hibernate-resume-generator/8/json"
        },
        {
            "name": "systemd-firstboot.service",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/systemd-firstboot.service/8/json"
        },
        {
            "name": "bootctl",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/bootctl/1/json"
        }
    ]
}