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NSYSCTL(8) System Manager's Manual NSYSCTL(8) NAME nsysctl -- get or set system state SYNOPSIS nsysctl [--libxo options [-r tagroot]] [-DdeFGgHIiJLnOpqTtVvWz] [-N | -hl [b | o | x]] [-B bufsize] [-f filename] [-j jailname] [-s sep] name[=value[,value]] ... nsysctl [--libxo options [-r tagroot]] [-DdeFGgHIJkLnOpqSTtVvWz] [-N | -hlu [b | o | x]] [-B bufsize] [-f filename] [-j jailname] [-s sep] -a DESCRIPTION The nsysctl utility is used to get or set the state of the system at runtime. The system exposes the available parameters as objects in a "Management Information Base" (MIB). nsysctl can explore the MIB, print object properties, retrieve or update their values, and display the output in both human and machine readable formats. Each object is identified by an "Object Identifier" (OID), which is a sequence of numbers. Numbers can be replaced with strings to form the object name. For example, "1.1" can be expressed as "kern.ostype". nsysctl accepts one or more object names, optionally followed by a new value. Alternatively, the -a flag can be used to display all available objects. nsysctl requires the sysctlinfo(4) interface. To load the required kernel module at boot time, place the following line in loader.conf(5): sysctlinfo_load="YES" The following options are available: --libxo options Generate output using libxo(3) in a variety of human and ma- chine readable formats. See xo_parse_args(3) for supported op- tions. -A Equivalent to -a -o. This option is obsolete. -a Display all objects. -b Print values in binary format. -B bufsize Use a buffer of bufsize bytes. -D Equivalent to -d -F -G -H -L -O -t. -d Show object descriptions. -e Use "=" as a key-value separator. -F Display the format string of each object. -f filename Load object names from filename. -G Show flags with their true (internal) values. -g Display flags associated with each object. -H Show the handler status of each object. -h Attempt to display values in a human-friendly format. -I Include internal nodes in the output. By default, only leaf nodes are shown. -i Ignore unknown objects. -J Show only objects flagged with PRISON. See jail(2) for de- tails. -j jailname Attach to the jail named jailname. See jail(2) and jls(8) for details. nsysctl initializes libxo(3), parses command-line op- tions, and attaches to the specified jail immediately after- ward. Any file specified with the -f option is read within the context of jailname. See jexec(8) for additional jail execu- tion methods. -k Include objects marked with the SKIP flag when used with -a. -L Display the aggregation label. -l Display the size of the value in bytes. -N Suppress value output. -n Suppress name output. -O Display the Object Identifier (OID). -o Display values in hexadecimal format, up to 16 bytes. -p Display property output in the format: "[PROPERTY-NAME]: property-value". -q Suppress certain warnings. -r tagroot Specify a tagroot for use with libxo(3). -S Also display the "sysctl.*" subtree when used with -a. -s sep Use sep as a separator. -T Show only objects that are settable via the loader. -t Display the type of each object. -u By default, -a hides objects without a value. This option dis- ables that behavior. -V Show only objects relevant to network subsystem virtualization, flagged with VNET. See vnet(9) for details. -v Display the nsysctl version and exit. -W Show only writable objects that are not marked as statistical. -X Equivalent to -a -x. This option is obsolete. -x Display values in hexadecimal format. -z Toggle the numeric or boolean value. A value of 0 becomes 1, and any non-zero value becomes 0. Only the first element of an array is modified. EXIT STATUS The nsysctl utility exits 0 on success, and >0 if an error occurs. EXAMPLES To retrieve the value of an object: % nsysctl kern.hostname To set the value of an object: % nsysctl kern.hostname=myBSD To display detailed information about an object: % nsysctl -pD kern.ostype To display object information in XML format: % nsysctl --libxo=xml,pretty -D kern.ostype COMPATIBILITY sysctl(8) prints internal and SKIP nodes when used with -aN, -ad, or -at. Otherwise, it only prints leaf nodes, skipping those marked with SKIP. To reproduce the same behavior with nsysctl, use the following equiva- lents: /sbin/sysctl /usr/local/sbin/nsysctl % sysctl -aN % nsysctl -aNIk % sysctl -ad % nsysctl -adIk % sysctl -at % nsysctl -atIk SEE ALSO jail(2), sysctl(3), sysctlmibinfo2(3), xo_parse_args(3), sysctlinfo(4), jexec(8), jls(8), sysctl(8) AUTHORS nsysctl was written by Alfonso Sabato Siciliano <asiciliano@FreeBSD.org>. FreeBSD 15.0 June 28, 2025 NSYSCTL(8)
NAME | SYNOPSIS | DESCRIPTION | EXIT STATUS | EXAMPLES | COMPATIBILITY | SEE ALSO | AUTHORS
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