{ "mode": "man", "parameter": "journalctl", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/journalctl/1/json", "generated": "2026-06-10T16:12:27Z", "synopsis": "journalctl [OPTIONS...] [MATCHES...]", "sections": { "NAME": { "content": "journalctl - Query the systemd journal\n", "subsections": [] }, "SYNOPSIS": { "content": "journalctl [OPTIONS...] [MATCHES...]\n", "subsections": [] }, "DESCRIPTION": { "content": "journalctl may be used to query the contents of the systemd(1) journal as written by systemd-\njournald.service(8).\n\nIf called without parameters, it will show the full contents of the journal, starting with\nthe oldest entry collected.\n\nIf one or more match arguments are passed, the output is filtered accordingly. A match is in\nthe format \"FIELD=VALUE\", e.g. \"SYSTEMDUNIT=httpd.service\", referring to the components of\na structured journal entry. See systemd.journal-fields(7) for a list of well-known fields. If\nmultiple matches are specified matching different fields, the log entries are filtered by\nboth, i.e. the resulting output will show only entries matching all the specified matches of\nthis kind. If two matches apply to the same field, then they are automatically matched as\nalternatives, i.e. the resulting output will show entries matching any of the specified\nmatches for the same field. Finally, the character \"+\" may appear as a separate word between\nother terms on the command line. This causes all matches before and after to be combined in a\ndisjunction (i.e. logical OR).\n\nIt is also possible to filter the entries by specifying an absolute file path as an argument.\nThe file path may be a file or a symbolic link and the file must exist at the time of the\nquery. If a file path refers to an executable binary, an \"EXE=\" match for the canonicalized\nbinary path is added to the query. If a file path refers to an executable script, a \"COMM=\"\nmatch for the script name is added to the query. If a file path refers to a device node,\n\"KERNELDEVICE=\" matches for the kernel name of the device and for each of its ancestor\ndevices is added to the query. Symbolic links are dereferenced, kernel names are synthesized,\nand parent devices are identified from the environment at the time of the query. In general,\na device node is the best proxy for an actual device, as log entries do not usually contain\nfields that identify an actual device. For the resulting log entries to be correct for the\nactual device, the relevant parts of the environment at the time the entry was logged, in\nparticular the actual device corresponding to the device node, must have been the same as\nthose at the time of the query. Because device nodes generally change their corresponding\ndevices across reboots, specifying a device node path causes the resulting entries to be\nrestricted to those from the current boot.\n\nAdditional constraints may be added using options --boot, --unit=, etc., to further limit\nwhat entries will be shown (logical AND).\n\nOutput is interleaved from all accessible journal files, whether they are rotated or\ncurrently being written, and regardless of whether they belong to the system itself or are\naccessible user journals. The --header option can be used to identify which files are being\nshown.\n\nThe set of journal files which will be used can be modified using the --user, --system,\n--directory, and --file options, see below.\n\nAll users are granted access to their private per-user journals. However, by default, only\nroot and users who are members of a few special groups are granted access to the system\njournal and the journals of other users. Members of the groups \"systemd-journal\", \"adm\", and\n\"wheel\" can read all journal files. Note that the two latter groups traditionally have\nadditional privileges specified by the distribution. Members of the \"wheel\" group can often\nperform administrative tasks.\n\nThe output is paged through less by default, and long lines are \"truncated\" to screen width.\nThe hidden part can be viewed by using the left-arrow and right-arrow keys. Paging can be\ndisabled; see the --no-pager option and the \"Environment\" section below.\n\nWhen outputting to a tty, lines are colored according to priority: lines of level ERROR and\nhigher are colored red; lines of level NOTICE and higher are highlighted; lines of level\nDEBUG are colored lighter grey; other lines are displayed normally.\n", "subsections": [] }, "OPTIONS": { "content": "The following options are understood:\n\n--no-full, --full, -l\nEllipsize fields when they do not fit in available columns. The default is to show full\nfields, allowing them to wrap or be truncated by the pager, if one is used.\n\nThe old options -l/--full are not useful anymore, except to undo --no-full.\n", "subsections": [ { "name": "-a --all", "content": "Show all fields in full, even if they include unprintable characters or are very long. By\ndefault, fields with unprintable characters are abbreviated as \"blob data\". (Note that\nthe pager may escape unprintable characters again.)\n", "flag": "-a", "long": "--all" }, { "name": "-f --follow", "content": "Show only the most recent journal entries, and continuously print new entries as they are\nappended to the journal.\n", "flag": "-f", "long": "--follow" }, { "name": "-e --pager-end", "content": "Immediately jump to the end of the journal inside the implied pager tool. This implies\n-n1000 to guarantee that the pager will not buffer logs of unbounded size. This may be\noverridden with an explicit -n with some other numeric value, while -nall will disable\nthis cap. Note that this option is only supported for the less(1) pager.\n", "flag": "-e", "long": "--pager-end" }, { "name": "-n --lines=", "content": "Show the most recent journal events and limit the number of events shown. If --follow is\nused, this option is implied. The argument is a positive integer or \"all\" to disable line\nlimiting. The default value is 10 if no argument is given.\n", "flag": "-n" }, { "name": "--no-tail", "content": "Show all stored output lines, even in follow mode. Undoes the effect of --lines=.\n", "long": "--no-tail" }, { "name": "-r --reverse", "content": "Reverse output so that the newest entries are displayed first.\n", "flag": "-r", "long": "--reverse" }, { "name": "-o --output=", "content": "Controls the formatting of the journal entries that are shown. Takes one of the following\noptions:\n\nshort\nis the default and generates an output that is mostly identical to the formatting of\nclassic syslog files, showing one line per journal entry.\n\nshort-full\nis very similar, but shows timestamps in the format the --since= and --until= options\naccept. Unlike the timestamp information shown in short output mode this mode\nincludes weekday, year and timezone information in the output, and is\nlocale-independent.\n\nshort-iso\nis very similar, but shows ISO 8601 wallclock timestamps.\n\nshort-iso-precise\nas for short-iso but includes full microsecond precision.\n\nshort-precise\nis very similar, but shows classic syslog timestamps with full microsecond precision.\n\nshort-monotonic\nis very similar, but shows monotonic timestamps instead of wallclock timestamps.\n\nshort-unix\nis very similar, but shows seconds passed since January 1st 1970 UTC instead of\nwallclock timestamps (\"UNIX time\"). The time is shown with microsecond accuracy.\n\nverbose\nshows the full-structured entry items with all fields.\n\nexport\nserializes the journal into a binary (but mostly text-based) stream suitable for\nbackups and network transfer (see Journal Export Format[1] for more information). To\nimport the binary stream back into native journald format use systemd-journal-\nremote(8).\n\njson\nformats entries as JSON objects, separated by newline characters (see Journal JSON\nFormat[2] for more information). Field values are generally encoded as JSON strings,\nwith three exceptions:\n\n1. Fields larger than 4096 bytes are encoded as null values. (This may be turned off\nby passing --all, but be aware that this may allocate overly long JSON objects.)\n\n2. Journal entries permit non-unique fields within the same log entry. JSON does not\nallow non-unique fields within objects. Due to this, if a non-unique field is\nencountered a JSON array is used as field value, listing all field values as\nelements.\n\n3. Fields containing non-printable or non-UTF8 bytes are encoded as arrays\ncontaining the raw bytes individually formatted as unsigned numbers.\n\nNote that this encoding is reversible (with the exception of the size limit).\n\njson-pretty\nformats entries as JSON data structures, but formats them in multiple lines in order\nto make them more readable by humans.\n\njson-sse\nformats entries as JSON data structures, but wraps them in a format suitable for\nServer-Sent Events[3].\n\njson-seq\nformats entries as JSON data structures, but prefixes them with an ASCII Record\nSeparator character (0x1E) and suffixes them with an ASCII Line Feed character\n(0x0A), in accordance with JavaScript Object Notation (JSON) Text Sequences[4]\n(\"application/json-seq\").\n\ncat\ngenerates a very terse output, only showing the actual message of each journal entry\nwith no metadata, not even a timestamp. If combined with the --output-fields= option\nwill output the listed fields for each log record, instead of the message.\n\nwith-unit\nsimilar to short-full, but prefixes the unit and user unit names instead of the\ntraditional syslog identifier. Useful when using templated instances, as it will\ninclude the arguments in the unit names.\n", "flag": "-o" }, { "name": "--output-fields=", "content": "A comma separated list of the fields which should be included in the output. This has an\neffect only for the output modes which would normally show all fields (verbose, export,\njson, json-pretty, json-sse and json-seq), as well as on cat. For the former, the\n\"CURSOR\", \"REALTIMETIMESTAMP\", \"MONOTONICTIMESTAMP\", and \"BOOTID\" fields are\nalways printed.\n" }, { "name": "--utc", "content": "Express time in Coordinated Universal Time (UTC).\n", "long": "--utc" }, { "name": "--no-hostname", "content": "Don't show the hostname field of log messages originating from the local host. This\nswitch has an effect only on the short family of output modes (see above).\n\nNote: this option does not remove occurrences of the hostname from log entries\nthemselves, so it does not prevent the hostname from being visible in the logs.\n", "long": "--no-hostname" }, { "name": "-x --catalog", "content": "Augment log lines with explanation texts from the message catalog. This will add\nexplanatory help texts to log messages in the output where this is available. These short\nhelp texts will explain the context of an error or log event, possible solutions, as well\nas pointers to support forums, developer documentation, and any other relevant manuals.\nNote that help texts are not available for all messages, but only for selected ones. For\nmore information on the message catalog, please refer to the Message Catalog Developer\nDocumentation[5].\n\nNote: when attaching journalctl output to bug reports, please do not use -x.\n", "flag": "-x", "long": "--catalog" }, { "name": "-q --quiet", "content": "Suppresses all informational messages (i.e. \"-- Journal begins at ...\", \"-- Reboot --\"),\nany warning messages regarding inaccessible system journals when run as a normal user.\n", "flag": "-q", "long": "--quiet" }, { "name": "-m --merge", "content": "Show entries interleaved from all available journals, including remote ones.\n", "flag": "-m", "long": "--merge" }, { "name": "-b --boot[=[", "content": "Show messages from a specific boot. This will add a match for \"BOOTID=\".\n\nThe argument may be empty, in which case logs for the current boot will be shown.\n\nIf the boot ID is omitted, a positive offset will look up the boots starting from the\nbeginning of the journal, and an equal-or-less-than zero offset will look up boots\nstarting from the end of the journal. Thus, 1 means the first boot found in the journal\nin chronological order, 2 the second and so on; while -0 is the last boot, -1 the boot\nbefore last, and so on. An empty offset is equivalent to specifying -0, except when the\ncurrent boot is not the last boot (e.g. because --directory was specified to look at logs\nfrom a different machine).\n\nIf the 32-character ID is specified, it may optionally be followed by offset which\nidentifies the boot relative to the one given by boot ID. Negative values mean earlier\nboots and positive values mean later boots. If offset is not specified, a value of zero\nis assumed, and the logs for the boot given by ID are shown.\n\nThe special argument all can be used to negate the effect of an earlier use of -b.\n", "flag": "-b" }, { "name": "--list-boots", "content": "Show a tabular list of boot numbers (relative to the current boot), their IDs, and the\ntimestamps of the first and last message pertaining to the boot.\n", "long": "--list-boots" }, { "name": "-k --dmesg", "content": "Show only kernel messages. This implies -b and adds the match \"TRANSPORT=kernel\".\n", "flag": "-k", "long": "--dmesg" }, { "name": "-t --identifier=", "content": "Show messages for the specified syslog identifier SYSLOGIDENTIFIER.\n\nThis parameter can be specified multiple times.\n", "flag": "-t" }, { "name": "-u --unit=", "content": "Show messages for the specified systemd unit UNIT (such as a service unit), or for any of\nthe units matched by PATTERN. If a pattern is specified, a list of unit names found in\nthe journal is compared with the specified pattern and all that match are used. For each\nunit name, a match is added for messages from the unit (\"SYSTEMDUNIT=UNIT\"), along with\nadditional matches for messages from systemd and messages about coredumps for the\nspecified unit. A match is also added for \"SYSTEMDSLICE=UNIT\", such that if the\nprovided UNIT is a systemd.slice(5) unit, all logs of children of the slice will be\nshown.\n\nThis parameter can be specified multiple times.\n", "flag": "-u" }, { "name": "--user-unit=", "content": "Show messages for the specified user session unit. This will add a match for messages\nfrom the unit (\"SYSTEMDUSERUNIT=\" and \"UID=\") and additional matches for messages\nfrom session systemd and messages about coredumps for the specified unit. A match is also\nadded for \"SYSTEMDUSERSLICE=UNIT\", such that if the provided UNIT is a\nsystemd.slice(5) unit, all logs of children of the unit will be shown.\n\nThis parameter can be specified multiple times.\n" }, { "name": "-p --priority=", "content": "Filter output by message priorities or priority ranges. Takes either a single numeric or\ntextual log level (i.e. between 0/\"emerg\" and 7/\"debug\"), or a range of numeric/text log\nlevels in the form FROM..TO. The log levels are the usual syslog log levels as documented\nin syslog(3), i.e. \"emerg\" (0), \"alert\" (1), \"crit\" (2), \"err\" (3), \"warning\" (4),\n\"notice\" (5), \"info\" (6), \"debug\" (7). If a single log level is specified, all messages\nwith this log level or a lower (hence more important) log level are shown. If a range is\nspecified, all messages within the range are shown, including both the start and the end\nvalue of the range. This will add \"PRIORITY=\" matches for the specified priorities.\n", "flag": "-p" }, { "name": "--facility=", "content": "Filter output by syslog facility. Takes a comma-separated list of numbers or facility\nnames. The names are the usual syslog facilities as documented in syslog(3).\n--facility=help may be used to display a list of known facility names and exit.\n" }, { "name": "-g --grep=", "content": "Filter output to entries where the MESSAGE= field matches the specified regular\nexpression. PERL-compatible regular expressions are used, see pcre2pattern(3) for a\ndetailed description of the syntax.\n\nIf the pattern is all lowercase, matching is case insensitive. Otherwise, matching is\ncase sensitive. This can be overridden with the --case-sensitive option, see below.\n", "flag": "-g" }, { "name": "--case-sensitive[=BOOLEAN]", "content": "Make pattern matching case sensitive or case insensitive.\n" }, { "name": "-c --cursor=", "content": "Start showing entries from the location in the journal specified by the passed cursor.\n\n--cursor-file=FILE\nIf FILE exists and contains a cursor, start showing entries after this location.\nOtherwise the show entries according the other given options. At the end, write the\ncursor of the last entry to FILE. Use this option to continually read the journal by\nsequentially calling journalctl.\n", "flag": "-c" }, { "name": "--after-cursor=", "content": "Start showing entries from the location in the journal after the location specified by\nthe passed cursor. The cursor is shown when the --show-cursor option is used.\n" }, { "name": "--show-cursor", "content": "The cursor is shown after the last entry after two dashes:\n\n-- cursor: s=0639...\n\nThe format of the cursor is private and subject to change.\n", "long": "--show-cursor" }, { "name": "-S --since= -U --until=", "content": "Start showing entries on or newer than the specified date, or on or older than the\nspecified date, respectively. Date specifications should be of the format \"2012-10-30\n18:17:16\". If the time part is omitted, \"00:00:00\" is assumed. If only the seconds\ncomponent is omitted, \":00\" is assumed. If the date component is omitted, the current day\nis assumed. Alternatively the strings \"yesterday\", \"today\", \"tomorrow\" are understood,\nwhich refer to 00:00:00 of the day before the current day, the current day, or the day\nafter the current day, respectively. \"now\" refers to the current time. Finally, relative\ntimes may be specified, prefixed with \"-\" or \"+\", referring to times before or after the\ncurrent time, respectively. For complete time and date specification, see\nsystemd.time(7). Note that --output=short-full prints timestamps that follow precisely\nthis format.\n", "flag": "-U" }, { "name": "-F --field=", "content": "Print all possible data values the specified field can take in all entries of the\njournal.\n", "flag": "-F" }, { "name": "-N --fields", "content": "Print all field names currently used in all entries of the journal.\n\n--system, --user\nShow messages from system services and the kernel (with --system). Show messages from\nservice of current user (with --user). If neither is specified, show all messages that\nthe user can see.\n", "flag": "-N", "long": "--fields" }, { "name": "-M --machine=", "content": "Show messages from a running, local container. Specify a container name to connect to.\n", "flag": "-M" }, { "name": "-D --directory=", "content": "Takes a directory path as argument. If specified, journalctl will operate on the\nspecified journal directory DIR instead of the default runtime and system journal paths.\n\n--file=GLOB\nTakes a file glob as an argument. If specified, journalctl will operate on the specified\njournal files matching GLOB instead of the default runtime and system journal paths. May\nbe specified multiple times, in which case files will be suitably interleaved.\n\n--root=ROOT\nTakes a directory path as an argument. If specified, journalctl will operate on journal\ndirectories and catalog file hierarchy underneath the specified directory instead of the\nroot directory (e.g. --update-catalog will create ROOT/var/lib/systemd/catalog/database,\nand journal files under ROOT/run/journal/ or ROOT/var/log/journal/ will be displayed).\n\n--image=IMAGE\nTakes a path to a disk image file or block device node. If specified, journalctl will\noperate on the file system in the indicated disk image. This is similar to --root= but\noperates on file systems stored in disk images or block devices, thus providing an easy\nway to extract log data from disk images. The disk image should either contain just a\nfile system or a set of file systems within a GPT partition table, following the\nDiscoverable Partitions Specification[6]. For further information on supported disk\nimages, see systemd-nspawn(1)'s switch of the same name.\n\n--namespace=NAMESPACE\nTakes a journal namespace identifier string as argument. If not specified the data\ncollected by the default namespace is shown. If specified shows the log data of the\nspecified namespace instead. If the namespace is specified as \"*\" data from all\nnamespaces is shown, interleaved. If the namespace identifier is prefixed with \"+\" data\nfrom the specified namespace and the default namespace is shown, interleaved, but no\nother. For details about journal namespaces see systemd-journald.service(8).\n", "flag": "-D" }, { "name": "--header", "content": "Instead of showing journal contents, show internal header information of the journal\nfields accessed.\n\nThis option is particularly useful when trying to identify out-of-order journal entries,\nas happens for example when the machine is booted with the wrong system time.\n", "long": "--header" }, { "name": "--disk-usage", "content": "Shows the current disk usage of all journal files. This shows the sum of the disk usage\nof all archived and active journal files.\n\n--vacuum-size=, --vacuum-time=, --vacuum-files=\nRemoves the oldest archived journal files until the disk space they use falls below the\nspecified size (specified with the usual \"K\", \"M\", \"G\" and \"T\" suffixes), or all archived\njournal files contain no data older than the specified timespan (specified with the usual\n\"s\", \"m\", \"h\", \"days\", \"months\", \"weeks\" and \"years\" suffixes), or no more than the\nspecified number of separate journal files remain. Note that running --vacuum-size= has\nonly an indirect effect on the output shown by --disk-usage, as the latter includes\nactive journal files, while the vacuuming operation only operates on archived journal\nfiles. Similarly, --vacuum-files= might not actually reduce the number of journal files\nto below the specified number, as it will not remove active journal files.\n\n--vacuum-size=, --vacuum-time= and --vacuum-files= may be combined in a single invocation\nto enforce any combination of a size, a time and a number of files limit on the archived\njournal files. Specifying any of these three parameters as zero is equivalent to not\nenforcing the specific limit, and is thus redundant.\n\nThese three switches may also be combined with --rotate into one command. If so, all\nactive files are rotated first, and the requested vacuuming operation is executed right\nafter. The rotation has the effect that all currently active files are archived (and\npotentially new, empty journal files opened as replacement), and hence the vacuuming\noperation has the greatest effect as it can take all log data written so far into\naccount.\n\n--list-catalog [128-bit-ID...]\nList the contents of the message catalog as a table of message IDs, plus their short\ndescription strings.\n\nIf any 128-bit-IDs are specified, only those entries are shown.\n\n--dump-catalog [128-bit-ID...]\nShow the contents of the message catalog, with entries separated by a line consisting of\ntwo dashes and the ID (the format is the same as .catalog files).\n\nIf any 128-bit-IDs are specified, only those entries are shown.\n", "long": "--disk-usage" }, { "name": "--update-catalog", "content": "Update the message catalog index. This command needs to be executed each time new catalog\nfiles are installed, removed, or updated to rebuild the binary catalog index.\n", "long": "--update-catalog" }, { "name": "--setup-keys", "content": "Instead of showing journal contents, generate a new key pair for Forward Secure Sealing\n(FSS). This will generate a sealing key and a verification key. The sealing key is stored\nin the journal data directory and shall remain on the host. The verification key should\nbe stored externally. Refer to the Seal= option in journald.conf(5) for information on\nForward Secure Sealing and for a link to a refereed scholarly paper detailing the\ncryptographic theory it is based on.\n", "long": "--setup-keys" }, { "name": "--force", "content": "When --setup-keys is passed and Forward Secure Sealing (FSS) has already been configured,\nrecreate FSS keys.\n", "long": "--force" }, { "name": "--interval=", "content": "Specifies the change interval for the sealing key when generating an FSS key pair with\n--setup-keys. Shorter intervals increase CPU consumption but shorten the time range of\nundetectable journal alterations. Defaults to 15min.\n" }, { "name": "--verify", "content": "Check the journal file for internal consistency. If the file has been generated with FSS\nenabled and the FSS verification key has been specified with --verify-key=, authenticity\nof the journal file is verified.\n", "long": "--verify" }, { "name": "--verify-key=", "content": "Specifies the FSS verification key to use for the --verify operation.\n" }, { "name": "--sync", "content": "Asks the journal daemon to write all yet unwritten journal data to the backing file\nsystem and synchronize all journals. This call does not return until the synchronization\noperation is complete. This command guarantees that any log messages written before its\ninvocation are safely stored on disk at the time it returns.\n", "long": "--sync" }, { "name": "--flush", "content": "Asks the journal daemon to flush any log data stored in /run/log/journal/ into\n/var/log/journal/, if persistent storage is enabled. This call does not return until the\noperation is complete. Note that this call is idempotent: the data is only flushed from\n/run/log/journal/ into /var/log/journal/ once during system runtime (but see\n--relinquish-var below), and this command exits cleanly without executing any operation\nif this has already happened. This command effectively guarantees that all data is\nflushed to /var/log/journal/ at the time it returns.\n", "long": "--flush" }, { "name": "--relinquish-var", "content": "Asks the journal daemon for the reverse operation to --flush: if requested the daemon\nwill write further log data to /run/log/journal/ and stops writing to /var/log/journal/.\nA subsequent call to --flush causes the log output to switch back to /var/log/journal/,\nsee above.\n", "long": "--relinquish-var" }, { "name": "--smart-relinquish-var", "content": "Similar to --relinquish-var but executes no operation if the root file system and\n/var/lib/journal/ reside on the same mount point. This operation is used during system\nshutdown in order to make the journal daemon stop writing data to /var/log/journal/ in\ncase that directory is located on a mount point that needs to be unmounted.\n", "long": "--smart-relinquish-var" }, { "name": "--rotate", "content": "Asks the journal daemon to rotate journal files. This call does not return until the\nrotation operation is complete. Journal file rotation has the effect that all currently\nactive journal files are marked as archived and renamed, so that they are never written\nto in future. New (empty) journal files are then created in their place. This operation\nmay be combined with --vacuum-size=, --vacuum-time= and --vacuum-file= into a single\ncommand, see above.\n", "long": "--rotate" }, { "name": "-h --help", "content": "Print a short help text and exit.\n", "flag": "-h", "long": "--help" }, { "name": "--version", "content": "Print a short version string and exit.\n", "long": "--version" }, { "name": "--no-pager", "content": "Do not pipe output into a pager.\n", "long": "--no-pager" } ] }, "EXIT STATUS": { "content": "On success, 0 is returned; otherwise, a non-zero failure code is returned.\n", "subsections": [] }, "ENVIRONMENT": { "content": "$SYSTEMDLOGLEVEL\nThe maximum log level of emitted messages (messages with a higher log level, i.e. less\nimportant ones, will be suppressed). Either one of (in order of decreasing importance)\nemerg, alert, crit, err, warning, notice, info, debug, or an integer in the range 0...7.\nSee syslog(3) for more information.\n\n$SYSTEMDLOGCOLOR\nA boolean. If true, messages written to the tty will be colored according to priority.\n\nThis setting is only useful when messages are written directly to the terminal, because\njournalctl(1) and other tools that display logs will color messages based on the log\nlevel on their own.\n\n$SYSTEMDLOGTIME\nA boolean. If true, console log messages will be prefixed with a timestamp.\n\nThis setting is only useful when messages are written directly to the terminal or a file,\nbecause journalctl(1) and other tools that display logs will attach timestamps based on\nthe entry metadata on their own.\n\n$SYSTEMDLOGLOCATION\nA boolean. If true, messages will be prefixed with a filename and line number in the\nsource code where the message originates.\n\nNote that the log location is often attached as metadata to journal entries anyway.\nIncluding it directly in the message text can nevertheless be convenient when debugging\nprograms.\n\n$SYSTEMDLOGTID\nA boolean. If true, messages will be prefixed with the current numerical thread ID (TID).\n\nNote that the this information is attached as metadata to journal entries anyway.\nIncluding it directly in the message text can nevertheless be convenient when debugging\nprograms.\n\n$SYSTEMDLOGTARGET\nThe destination for log messages. One of console (log to the attached tty),\nconsole-prefixed (log to the attached tty but with prefixes encoding the log level and\n\"facility\", see syslog(3), kmsg (log to the kernel circular log buffer), journal (log to\nthe journal), journal-or-kmsg (log to the journal if available, and to kmsg otherwise),\nauto (determine the appropriate log target automatically, the default), null (disable log\noutput).\n\n$SYSTEMDPAGER\nPager to use when --no-pager is not given; overrides $PAGER. If neither $SYSTEMDPAGER\nnor $PAGER are set, a set of well-known pager implementations are tried in turn,\nincluding less(1) and more(1), until one is found. If no pager implementation is\ndiscovered no pager is invoked. Setting this environment variable to an empty string or\nthe value \"cat\" is equivalent to passing --no-pager.\n\n$SYSTEMDLESS\nOverride the options passed to less (by default \"FRSXMK\").\n\nUsers might want to change two options in particular:\n\nK\nThis option instructs the pager to exit immediately when Ctrl+C is pressed. To allow\nless to handle Ctrl+C itself to switch back to the pager command prompt, unset this\noption.\n\nIf the value of $SYSTEMDLESS does not include \"K\", and the pager that is invoked is\nless, Ctrl+C will be ignored by the executable, and needs to be handled by the pager.\n\nX\nThis option instructs the pager to not send termcap initialization and\ndeinitialization strings to the terminal. It is set by default to allow command\noutput to remain visible in the terminal even after the pager exits. Nevertheless,\nthis prevents some pager functionality from working, in particular paged output\ncannot be scrolled with the mouse.\n\nSee less(1) for more discussion.\n\n$SYSTEMDLESSCHARSET\nOverride the charset passed to less (by default \"utf-8\", if the invoking terminal is\ndetermined to be UTF-8 compatible).\n\n$SYSTEMDPAGERSECURE\nTakes a boolean argument. When true, the \"secure\" mode of the pager is enabled; if false,\ndisabled. If $SYSTEMDPAGERSECURE is not set at all, secure mode is enabled if the\neffective UID is not the same as the owner of the login session, see geteuid(2) and\nsdpidgetowneruid(3). In secure mode, LESSSECURE=1 will be set when invoking the\npager, and the pager shall disable commands that open or create new files or start new\nsubprocesses. When $SYSTEMDPAGERSECURE is not set at all, pagers which are not known to\nimplement secure mode will not be used. (Currently only less(1) implements secure mode.)\n\nNote: when commands are invoked with elevated privileges, for example under sudo(8) or\npkexec(1), care must be taken to ensure that unintended interactive features are not\nenabled. \"Secure\" mode for the pager may be enabled automatically as describe above.\nSetting SYSTEMDPAGERSECURE=0 or not removing it from the inherited environment allows\nthe user to invoke arbitrary commands. Note that if the $SYSTEMDPAGER or $PAGER\nvariables are to be honoured, $SYSTEMDPAGERSECURE must be set too. It might be\nreasonable to completely disable the pager using --no-pager instead.\n\n$SYSTEMDCOLORS\nTakes a boolean argument. When true, systemd and related utilities will use colors in\ntheir output, otherwise the output will be monochrome. Additionally, the variable can\ntake one of the following special values: \"16\", \"256\" to restrict the use of colors to\nthe base 16 or 256 ANSI colors, respectively. This can be specified to override the\nautomatic decision based on $TERM and what the console is connected to.\n\n$SYSTEMDURLIFY\nThe value must be a boolean. Controls whether clickable links should be generated in the\noutput for terminal emulators supporting this. This can be specified to override the\ndecision that systemd makes based on $TERM and other conditions.\n", "subsections": [] }, "EXAMPLES": { "content": "Without arguments, all collected logs are shown unfiltered:\n\njournalctl\n\nWith one match specified, all entries with a field matching the expression are shown:\n\njournalctl SYSTEMDUNIT=avahi-daemon.service\njournalctl SYSTEMDCGROUP=/user.slice/user-42.slice/session-c1.scope\n\nIf two different fields are matched, only entries matching both expressions at the same time\nare shown:\n\njournalctl SYSTEMDUNIT=avahi-daemon.service PID=28097\n\nIf two matches refer to the same field, all entries matching either expression are shown:\n\njournalctl SYSTEMDUNIT=avahi-daemon.service SYSTEMDUNIT=dbus.service\n\nIf the separator \"+\" is used, two expressions may be combined in a logical OR. The following\nwill show all messages from the Avahi service process with the PID 28097 plus all messages\nfrom the D-Bus service (from any of its processes):\n\njournalctl SYSTEMDUNIT=avahi-daemon.service PID=28097 + SYSTEMDUNIT=dbus.service\n\nTo show all fields emitted by a unit and about the unit, option -u/--unit= should be used.\njournalctl -u name expands to a complex filter similar to\n\nSYSTEMDUNIT=name.service\n+ UNIT=name.service PID=1\n+ OBJECTSYSTEMDUNIT=name.service UID=0\n+ COREDUMPUNIT=name.service UID=0 MESSAGEID=fc2e22bc6ee647b6b90729ab34a250b1\n\n\n(see systemd.journal-fields(7) for an explanation of those patterns).\n\nShow all logs generated by the D-Bus executable:\n\njournalctl /usr/bin/dbus-daemon\n\nShow all kernel logs from previous boot:\n\njournalctl -k -b -1\n\nShow a live log display from a system service apache.service:\n\njournalctl -f -u apache\n", "subsections": [] }, "SEE ALSO": { "content": "systemd(1), systemd-journald.service(8), systemctl(1), coredumpctl(1), systemd.journal-\nfields(7), journald.conf(5), systemd.time(7), systemd-journal-remote.service(8), systemd-\njournal-upload.service(8)\n", "subsections": [] }, "NOTES": { "content": "1. Journal Export Format\nhttps://systemd.io/JOURNALEXPORTFORMATS#journal-export-format\n\n2. Journal JSON Format\nhttps://systemd.io/JOURNALEXPORTFORMATS#journal-json-format\n\n3. Server-Sent Events\nhttps://developer.mozilla.org/en-US/docs/Server-sentevents/Usingserver-sentevents\n\n4. JavaScript Object Notation (JSON) Text Sequences\nhttps://tools.ietf.org/html/rfc7464\n\n5. Message Catalog Developer Documentation\nhttps://www.freedesktop.org/wiki/Software/systemd/catalog\n\n6. Discoverable Partitions Specification\nhttps://systemd.io/DISCOVERABLEPARTITIONS\n\n\n\nsystemd 249 JOURNALCTL(1)", "subsections": [] } }, "summary": "journalctl - Query the systemd journal", "flags": [ { "flag": "-a", "long": "--all", "arg": null, "description": "Show all fields in full, even if they include unprintable characters or are very long. By default, fields with unprintable characters are abbreviated as \"blob data\". (Note that the pager may escape unprintable characters again.)" }, { "flag": "-f", "long": "--follow", "arg": null, "description": "Show only the most recent journal entries, and continuously print new entries as they are appended to the journal." }, { "flag": "-e", "long": "--pager-end", "arg": null, "description": "Immediately jump to the end of the journal inside the implied pager tool. This implies -n1000 to guarantee that the pager will not buffer logs of unbounded size. This may be overridden with an explicit -n with some other numeric value, while -nall will disable this cap. Note that this option is only supported for the less(1) pager." }, { "flag": "-n", "long": null, "arg": null, "description": "Show the most recent journal events and limit the number of events shown. If --follow is used, this option is implied. The argument is a positive integer or \"all\" to disable line limiting. The default value is 10 if no argument is given." }, { "flag": "", "long": "--no-tail", "arg": null, "description": "Show all stored output lines, even in follow mode. Undoes the effect of --lines=." }, { "flag": "-r", "long": "--reverse", "arg": null, "description": "Reverse output so that the newest entries are displayed first." }, { "flag": "-o", "long": null, "arg": null, "description": "Controls the formatting of the journal entries that are shown. Takes one of the following options: short is the default and generates an output that is mostly identical to the formatting of classic syslog files, showing one line per journal entry. short-full is very similar, but shows timestamps in the format the --since= and --until= options accept. Unlike the timestamp information shown in short output mode this mode includes weekday, year and timezone information in the output, and is locale-independent. short-iso is very similar, but shows ISO 8601 wallclock timestamps. short-iso-precise as for short-iso but includes full microsecond precision. short-precise is very similar, but shows classic syslog timestamps with full microsecond precision. short-monotonic is very similar, but shows monotonic timestamps instead of wallclock timestamps. short-unix is very similar, but shows seconds passed since January 1st 1970 UTC instead of wallclock timestamps (\"UNIX time\"). The time is shown with microsecond accuracy. verbose shows the full-structured entry items with all fields. export serializes the journal into a binary (but mostly text-based) stream suitable for backups and network transfer (see Journal Export Format[1] for more information). To import the binary stream back into native journald format use systemd-journal- remote(8). json formats entries as JSON objects, separated by newline characters (see Journal JSON Format[2] for more information). Field values are generally encoded as JSON strings, with three exceptions: 1. Fields larger than 4096 bytes are encoded as null values. (This may be turned off by passing --all, but be aware that this may allocate overly long JSON objects.) 2. Journal entries permit non-unique fields within the same log entry. JSON does not allow non-unique fields within objects. Due to this, if a non-unique field is encountered a JSON array is used as field value, listing all field values as elements. 3. Fields containing non-printable or non-UTF8 bytes are encoded as arrays containing the raw bytes individually formatted as unsigned numbers. Note that this encoding is reversible (with the exception of the size limit). json-pretty formats entries as JSON data structures, but formats them in multiple lines in order to make them more readable by humans. json-sse formats entries as JSON data structures, but wraps them in a format suitable for Server-Sent Events[3]. json-seq formats entries as JSON data structures, but prefixes them with an ASCII Record Separator character (0x1E) and suffixes them with an ASCII Line Feed character (0x0A), in accordance with JavaScript Object Notation (JSON) Text Sequences[4] (\"application/json-seq\"). cat generates a very terse output, only showing the actual message of each journal entry with no metadata, not even a timestamp. If combined with the --output-fields= option will output the listed fields for each log record, instead of the message. with-unit similar to short-full, but prefixes the unit and user unit names instead of the traditional syslog identifier. Useful when using templated instances, as it will include the arguments in the unit names." }, { "flag": "", "long": null, "arg": null, "description": "A comma separated list of the fields which should be included in the output. This has an effect only for the output modes which would normally show all fields (verbose, export, json, json-pretty, json-sse and json-seq), as well as on cat. For the former, the \"CURSOR\", \"REALTIMETIMESTAMP\", \"MONOTONICTIMESTAMP\", and \"BOOTID\" fields are always printed." }, { "flag": "", "long": "--utc", "arg": null, "description": "Express time in Coordinated Universal Time (UTC)." }, { "flag": "", "long": "--no-hostname", "arg": null, "description": "Don't show the hostname field of log messages originating from the local host. This switch has an effect only on the short family of output modes (see above). Note: this option does not remove occurrences of the hostname from log entries themselves, so it does not prevent the hostname from being visible in the logs." }, { "flag": "-x", "long": "--catalog", "arg": null, "description": "Augment log lines with explanation texts from the message catalog. This will add explanatory help texts to log messages in the output where this is available. These short help texts will explain the context of an error or log event, possible solutions, as well as pointers to support forums, developer documentation, and any other relevant manuals. Note that help texts are not available for all messages, but only for selected ones. For more information on the message catalog, please refer to the Message Catalog Developer Documentation[5]. Note: when attaching journalctl output to bug reports, please do not use -x." }, { "flag": "-q", "long": "--quiet", "arg": null, "description": "Suppresses all informational messages (i.e. \"-- Journal begins at ...\", \"-- Reboot --\"), any warning messages regarding inaccessible system journals when run as a normal user." }, { "flag": "-m", "long": "--merge", "arg": null, "description": "Show entries interleaved from all available journals, including remote ones." }, { "flag": "-b", "long": null, "arg": null, "description": "Show messages from a specific boot. This will add a match for \"BOOTID=\". The argument may be empty, in which case logs for the current boot will be shown. If the boot ID is omitted, a positive offset will look up the boots starting from the beginning of the journal, and an equal-or-less-than zero offset will look up boots starting from the end of the journal. Thus, 1 means the first boot found in the journal in chronological order, 2 the second and so on; while -0 is the last boot, -1 the boot before last, and so on. An empty offset is equivalent to specifying -0, except when the current boot is not the last boot (e.g. because --directory was specified to look at logs from a different machine). If the 32-character ID is specified, it may optionally be followed by offset which identifies the boot relative to the one given by boot ID. Negative values mean earlier boots and positive values mean later boots. If offset is not specified, a value of zero is assumed, and the logs for the boot given by ID are shown. The special argument all can be used to negate the effect of an earlier use of -b." }, { "flag": "", "long": "--list-boots", "arg": null, "description": "Show a tabular list of boot numbers (relative to the current boot), their IDs, and the timestamps of the first and last message pertaining to the boot." }, { "flag": "-k", "long": "--dmesg", "arg": null, "description": "Show only kernel messages. This implies -b and adds the match \"TRANSPORT=kernel\"." }, { "flag": "-t", "long": null, "arg": null, "description": "Show messages for the specified syslog identifier SYSLOGIDENTIFIER. This parameter can be specified multiple times." }, { "flag": "-u", "long": null, "arg": null, "description": "Show messages for the specified systemd unit UNIT (such as a service unit), or for any of the units matched by PATTERN. If a pattern is specified, a list of unit names found in the journal is compared with the specified pattern and all that match are used. For each unit name, a match is added for messages from the unit (\"SYSTEMDUNIT=UNIT\"), along with additional matches for messages from systemd and messages about coredumps for the specified unit. A match is also added for \"SYSTEMDSLICE=UNIT\", such that if the provided UNIT is a systemd.slice(5) unit, all logs of children of the slice will be shown. This parameter can be specified multiple times." }, { "flag": "", "long": null, "arg": null, "description": "Show messages for the specified user session unit. This will add a match for messages from the unit (\"SYSTEMDUSERUNIT=\" and \"UID=\") and additional matches for messages from session systemd and messages about coredumps for the specified unit. A match is also added for \"SYSTEMDUSERSLICE=UNIT\", such that if the provided UNIT is a systemd.slice(5) unit, all logs of children of the unit will be shown. This parameter can be specified multiple times." }, { "flag": "-p", "long": null, "arg": null, "description": "Filter output by message priorities or priority ranges. Takes either a single numeric or textual log level (i.e. between 0/\"emerg\" and 7/\"debug\"), or a range of numeric/text log levels in the form FROM..TO. The log levels are the usual syslog log levels as documented in syslog(3), i.e. \"emerg\" (0), \"alert\" (1), \"crit\" (2), \"err\" (3), \"warning\" (4), \"notice\" (5), \"info\" (6), \"debug\" (7). If a single log level is specified, all messages with this log level or a lower (hence more important) log level are shown. If a range is specified, all messages within the range are shown, including both the start and the end value of the range. This will add \"PRIORITY=\" matches for the specified priorities." }, { "flag": "", "long": null, "arg": null, "description": "Filter output by syslog facility. Takes a comma-separated list of numbers or facility names. The names are the usual syslog facilities as documented in syslog(3). --facility=help may be used to display a list of known facility names and exit." }, { "flag": "-g", "long": null, "arg": null, "description": "Filter output to entries where the MESSAGE= field matches the specified regular expression. PERL-compatible regular expressions are used, see pcre2pattern(3) for a detailed description of the syntax. If the pattern is all lowercase, matching is case insensitive. Otherwise, matching is case sensitive. This can be overridden with the --case-sensitive option, see below." }, { "flag": "", "long": null, "arg": null, "description": "Make pattern matching case sensitive or case insensitive." }, { "flag": "-c", "long": null, "arg": null, "description": "Start showing entries from the location in the journal specified by the passed cursor. --cursor-file=FILE If FILE exists and contains a cursor, start showing entries after this location. Otherwise the show entries according the other given options. At the end, write the cursor of the last entry to FILE. Use this option to continually read the journal by sequentially calling journalctl." }, { "flag": "", "long": null, "arg": null, "description": "Start showing entries from the location in the journal after the location specified by the passed cursor. The cursor is shown when the --show-cursor option is used." }, { "flag": "", "long": "--show-cursor", "arg": null, "description": "The cursor is shown after the last entry after two dashes: -- cursor: s=0639... The format of the cursor is private and subject to change." }, { "flag": "-U", "long": null, "arg": null, "description": "Start showing entries on or newer than the specified date, or on or older than the specified date, respectively. Date specifications should be of the format \"2012-10-30 18:17:16\". If the time part is omitted, \"00:00:00\" is assumed. If only the seconds component is omitted, \":00\" is assumed. If the date component is omitted, the current day is assumed. Alternatively the strings \"yesterday\", \"today\", \"tomorrow\" are understood, which refer to 00:00:00 of the day before the current day, the current day, or the day after the current day, respectively. \"now\" refers to the current time. Finally, relative times may be specified, prefixed with \"-\" or \"+\", referring to times before or after the current time, respectively. For complete time and date specification, see systemd.time(7). Note that --output=short-full prints timestamps that follow precisely this format." }, { "flag": "-F", "long": null, "arg": null, "description": "Print all possible data values the specified field can take in all entries of the journal." }, { "flag": "-N", "long": "--fields", "arg": null, "description": "Print all field names currently used in all entries of the journal. --system, --user Show messages from system services and the kernel (with --system). Show messages from service of current user (with --user). If neither is specified, show all messages that the user can see." }, { "flag": "-M", "long": null, "arg": null, "description": "Show messages from a running, local container. Specify a container name to connect to." }, { "flag": "-D", "long": null, "arg": null, "description": "Takes a directory path as argument. If specified, journalctl will operate on the specified journal directory DIR instead of the default runtime and system journal paths. --file=GLOB Takes a file glob as an argument. If specified, journalctl will operate on the specified journal files matching GLOB instead of the default runtime and system journal paths. May be specified multiple times, in which case files will be suitably interleaved. --root=ROOT Takes a directory path as an argument. If specified, journalctl will operate on journal directories and catalog file hierarchy underneath the specified directory instead of the root directory (e.g. --update-catalog will create ROOT/var/lib/systemd/catalog/database, and journal files under ROOT/run/journal/ or ROOT/var/log/journal/ will be displayed). --image=IMAGE Takes a path to a disk image file or block device node. If specified, journalctl will operate on the file system in the indicated disk image. This is similar to --root= but operates on file systems stored in disk images or block devices, thus providing an easy way to extract log data from disk images. The disk image should either contain just a file system or a set of file systems within a GPT partition table, following the Discoverable Partitions Specification[6]. For further information on supported disk images, see systemd-nspawn(1)'s switch of the same name. --namespace=NAMESPACE Takes a journal namespace identifier string as argument. If not specified the data collected by the default namespace is shown. If specified shows the log data of the specified namespace instead. If the namespace is specified as \"*\" data from all namespaces is shown, interleaved. If the namespace identifier is prefixed with \"+\" data from the specified namespace and the default namespace is shown, interleaved, but no other. For details about journal namespaces see systemd-journald.service(8)." }, { "flag": "", "long": "--header", "arg": null, "description": "Instead of showing journal contents, show internal header information of the journal fields accessed. This option is particularly useful when trying to identify out-of-order journal entries, as happens for example when the machine is booted with the wrong system time." }, { "flag": "", "long": "--disk-usage", "arg": null, "description": "Shows the current disk usage of all journal files. This shows the sum of the disk usage of all archived and active journal files. --vacuum-size=, --vacuum-time=, --vacuum-files= Removes the oldest archived journal files until the disk space they use falls below the specified size (specified with the usual \"K\", \"M\", \"G\" and \"T\" suffixes), or all archived journal files contain no data older than the specified timespan (specified with the usual \"s\", \"m\", \"h\", \"days\", \"months\", \"weeks\" and \"years\" suffixes), or no more than the specified number of separate journal files remain. Note that running --vacuum-size= has only an indirect effect on the output shown by --disk-usage, as the latter includes active journal files, while the vacuuming operation only operates on archived journal files. Similarly, --vacuum-files= might not actually reduce the number of journal files to below the specified number, as it will not remove active journal files. --vacuum-size=, --vacuum-time= and --vacuum-files= may be combined in a single invocation to enforce any combination of a size, a time and a number of files limit on the archived journal files. Specifying any of these three parameters as zero is equivalent to not enforcing the specific limit, and is thus redundant. These three switches may also be combined with --rotate into one command. If so, all active files are rotated first, and the requested vacuuming operation is executed right after. The rotation has the effect that all currently active files are archived (and potentially new, empty journal files opened as replacement), and hence the vacuuming operation has the greatest effect as it can take all log data written so far into account. --list-catalog [128-bit-ID...] List the contents of the message catalog as a table of message IDs, plus their short description strings. If any 128-bit-IDs are specified, only those entries are shown. --dump-catalog [128-bit-ID...] Show the contents of the message catalog, with entries separated by a line consisting of two dashes and the ID (the format is the same as .catalog files). If any 128-bit-IDs are specified, only those entries are shown." }, { "flag": "", "long": "--update-catalog", "arg": null, "description": "Update the message catalog index. This command needs to be executed each time new catalog files are installed, removed, or updated to rebuild the binary catalog index." }, { "flag": "", "long": "--setup-keys", "arg": null, "description": "Instead of showing journal contents, generate a new key pair for Forward Secure Sealing (FSS). This will generate a sealing key and a verification key. The sealing key is stored in the journal data directory and shall remain on the host. The verification key should be stored externally. Refer to the Seal= option in journald.conf(5) for information on Forward Secure Sealing and for a link to a refereed scholarly paper detailing the cryptographic theory it is based on." }, { "flag": "", "long": "--force", "arg": null, "description": "When --setup-keys is passed and Forward Secure Sealing (FSS) has already been configured, recreate FSS keys." }, { "flag": "", "long": null, "arg": null, "description": "Specifies the change interval for the sealing key when generating an FSS key pair with --setup-keys. Shorter intervals increase CPU consumption but shorten the time range of undetectable journal alterations. Defaults to 15min." }, { "flag": "", "long": "--verify", "arg": null, "description": "Check the journal file for internal consistency. If the file has been generated with FSS enabled and the FSS verification key has been specified with --verify-key=, authenticity of the journal file is verified." }, { "flag": "", "long": null, "arg": null, "description": "Specifies the FSS verification key to use for the --verify operation." }, { "flag": "", "long": "--sync", "arg": null, "description": "Asks the journal daemon to write all yet unwritten journal data to the backing file system and synchronize all journals. This call does not return until the synchronization operation is complete. This command guarantees that any log messages written before its invocation are safely stored on disk at the time it returns." }, { "flag": "", "long": "--flush", "arg": null, "description": "Asks the journal daemon to flush any log data stored in /run/log/journal/ into /var/log/journal/, if persistent storage is enabled. This call does not return until the operation is complete. Note that this call is idempotent: the data is only flushed from /run/log/journal/ into /var/log/journal/ once during system runtime (but see --relinquish-var below), and this command exits cleanly without executing any operation if this has already happened. This command effectively guarantees that all data is flushed to /var/log/journal/ at the time it returns." }, { "flag": "", "long": "--relinquish-var", "arg": null, "description": "Asks the journal daemon for the reverse operation to --flush: if requested the daemon will write further log data to /run/log/journal/ and stops writing to /var/log/journal/. A subsequent call to --flush causes the log output to switch back to /var/log/journal/, see above." }, { "flag": "", "long": "--smart-relinquish-var", "arg": null, "description": "Similar to --relinquish-var but executes no operation if the root file system and /var/lib/journal/ reside on the same mount point. This operation is used during system shutdown in order to make the journal daemon stop writing data to /var/log/journal/ in case that directory is located on a mount point that needs to be unmounted." }, { "flag": "", "long": "--rotate", "arg": null, "description": "Asks the journal daemon to rotate journal files. This call does not return until the rotation operation is complete. Journal file rotation has the effect that all currently active journal files are marked as archived and renamed, so that they are never written to in future. New (empty) journal files are then created in their place. This operation may be combined with --vacuum-size=, --vacuum-time= and --vacuum-file= into a single command, see above." }, { "flag": "-h", "long": "--help", "arg": null, "description": "Print a short help text and exit." }, { "flag": "", "long": "--version", "arg": null, "description": "Print a short version string and exit." }, { "flag": "", "long": "--no-pager", "arg": null, "description": "Do not pipe output into a pager." } ], "examples": [ "Without arguments, all collected logs are shown unfiltered:", "journalctl", "With one match specified, all entries with a field matching the expression are shown:", "journalctl SYSTEMDUNIT=avahi-daemon.service", "journalctl SYSTEMDCGROUP=/user.slice/user-42.slice/session-c1.scope", "If two different fields are matched, only entries matching both expressions at the same time", "are shown:", "journalctl SYSTEMDUNIT=avahi-daemon.service PID=28097", "If two matches refer to the same field, all entries matching either expression are shown:", "journalctl SYSTEMDUNIT=avahi-daemon.service SYSTEMDUNIT=dbus.service", "If the separator \"+\" is used, two expressions may be combined in a logical OR. The following", "will show all messages from the Avahi service process with the PID 28097 plus all messages", "from the D-Bus service (from any of its processes):", "journalctl SYSTEMDUNIT=avahi-daemon.service PID=28097 + SYSTEMDUNIT=dbus.service", "To show all fields emitted by a unit and about the unit, option -u/--unit= should be used.", "journalctl -u name expands to a complex filter similar to", "SYSTEMDUNIT=name.service", "+ UNIT=name.service PID=1", "+ OBJECTSYSTEMDUNIT=name.service UID=0", "+ COREDUMPUNIT=name.service UID=0 MESSAGEID=fc2e22bc6ee647b6b90729ab34a250b1", "(see systemd.journal-fields(7) for an explanation of those patterns).", "Show all logs generated by the D-Bus executable:", "journalctl /usr/bin/dbus-daemon", "Show all kernel logs from previous boot:", "journalctl -k -b -1", "Show a live log display from a system service apache.service:", "journalctl -f -u apache" ], "see_also": [ { "name": "systemd", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/systemd/1/json" }, { "name": "systemd-journald.service", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/systemd-journald.service/8/json" }, { "name": "systemctl", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/systemctl/1/json" }, { "name": "coredumpctl", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/coredumpctl/1/json" }, { "name": "fields", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/fields/7/json" }, { "name": "journald.conf", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/journald.conf/5/json" }, { "name": "systemd.time", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/systemd.time/7/json" }, { "name": "systemd-journal-remote.service", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/systemd-journal-remote.service/8/json" }, { "name": "journal-upload.service", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/journal-upload.service/8/json" } ], "tldr": { "source": "official", "description": "Query the systemd journal.", "examples": [ { "description": "Show the latest `n` lines and follow new messages (like `tail --follow` for traditional syslog)", "command": "journalctl {{-n|--lines}} {{n}} {{-f|--follow}}" }, { "description": "Show all messages with priority level 3 (errors) from the boot before last shutdown", "command": "journalctl {{-b|--boot}} -1 {{-p|--priority}} 3" }, { "description": "Show all messages by a specific unit", "command": "journalctl {{-u|--unit}} {{unit}}" }, { "description": "Show logs for a given unit since the last time it started", "command": "journalctl _SYSTEMD_INVOCATION_ID=$(systemctl show --value --property=InvocationID {{unit}})" }, { "description": "Filter messages within a time range (either timestamp or placeholders like \"yesterday\")", "command": "journalctl {{-S|--since}} {{now|today|yesterday|tomorrow|...}} {{-U|--until}} \"{{YYYY-MM-DD HH:MM:SS}}\"" }, { "description": "Show all messages by a specific process", "command": "journalctl _PID={{pid}}" }, { "description": "Show all messages by a specific executable", "command": "journalctl {{path/to/executable}}" }, { "description": "Delete journal logs which are older than 2 days", "command": "journalctl --vacuum-time 2d" } ] } }