1SYSCTL(8) System Administration SYSCTL(8)
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6 sysctl - configure kernel parameters at runtime
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9 sysctl [options] [variable[=value]] [...]
10 sysctl -p [file or regexp] [...]
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13 sysctl is used to modify kernel parameters at runtime. The parameters
14 available are those listed under /proc/sys/. Procfs is required for
15 sysctl support in Linux. You can use sysctl to both read and write
16 sysctl data.
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19 variable
20 The name of a key to read from. An example is kernel.ostype.
21 The '/' separator is also accepted in place of a '.'.
22 variable=value
24 To set a key, use the form variable=value where variable is the
25 key and value is the value to set it to. If the value contains
26 quotes or characters which are parsed by the shell, you may need
27 to enclose the value in double quotes.
28 -n, --values
30 Use this option to disable printing of the key name when print‐
31 ing values.
32 -e, --ignore
34 Use this option to ignore errors about unknown keys.
35 -N, --names
37 Use this option to only print the names. It may be useful with
38 shells that have programmable completion.
39 -q, --quiet
41 Use this option to not display the values set to stdout.
42 -w, --write
44 Use this option when all arguments prescribe a key to be set.
45 -p[FILE], --load[=FILE]
47 Load in sysctl settings from the file specified or
48 /etc/sysctl.conf if none given. Specifying - as filename means
49 reading data from standard input. Using this option will mean
50 arguments to sysctl are files, which are read in the order they
51 are specified. The file argument may be specified as regular
52 expression.
53 -a, --all
55 Display all values currently available.
56 --deprecated
58 Include deprecated parameters to --all values listing.
59 -b, --binary
61 Print value without new line.
62 --system
64 Load settings from all system configuration files. Files are
65 read from directories in the following list in given order from
66 top to bottom. Once a file of a given filename is loaded, any
67 file of the same name in subsequent directories is ignored.
68 /etc/sysctl.d/*.conf
69 /run/sysctl.d/*.conf
70 /usr/local/lib/sysctl.d/*.conf
71 /usr/lib/sysctl.d/*.conf
72 /lib/sysctl.d/*.conf
73 /etc/sysctl.conf
74 -r, --pattern pattern
76 Only apply settings that match pattern. The pattern uses ex‐
77 tended regular expression syntax.
78 -A Alias of -a
80 -d Alias of -h
82 -f Alias of -p
84 -X Alias of -a
86 -o Does nothing, exists for BSD compatibility.
88 -x Does nothing, exists for BSD compatibility.
90 -h, --help
92 Display help text and exit.
93 -V, --version
95 Display version information and exit.
96
98 /sbin/sysctl -a
99 /sbin/sysctl -n kernel.hostname
100 /sbin/sysctl -w kernel.domainname="example.com"
101 /sbin/sysctl -p/etc/sysctl.conf
102 /sbin/sysctl -a --pattern forward
103 /sbin/sysctl -a --pattern forward$
104 /sbin/sysctl -a --pattern 'net.ipv4.conf.(eth|wlan)0.arp'
105 /sbin/sysctl --system --pattern '^net.ipv6'
106
108 The base_reachable_time and retrans_time are deprecated. The sysctl
109 command does not allow changing values of these parameters. Users who
110 insist to use deprecated kernel interfaces should push values to /proc
111 file system by other means. For example:
112 echo 256 > /proc/sys/net/ipv6/neigh/eth0/base_reachable_time
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116 /proc/sys
117 /etc/sysctl.d/*.conf
118 /run/sysctl.d/*.conf
119 /usr/local/lib/sysctl.d/*.conf
120 /usr/lib/sysctl.d/*.conf
121 /lib/sysctl.d/*.conf
122 /etc/sysctl.conf
123
125 sysctl.conf(5) regex(7)
126
128 George Staikos ⟨staikos@0wned.org⟩
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131 Please send bug reports to ⟨procps@freelists.org⟩
132procps-ng 2020-02-27 SYSCTL(8)