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.
17
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. This requires the -w
28 parameter to use.
29 -n, --values
31 Use this option to disable printing of the key name when print‐
32 ing values.
33 -e, --ignore
35 Use this option to ignore errors about unknown keys.
36 -N, --names
38 Use this option to only print the names. It may be useful with
39 shells that have programmable completion.
40 -q, --quiet
42 Use this option to not display the values set to stdout.
43 -w, --write
45 Use this option when you want to change a sysctl setting.
46 -p[FILE], --load[=FILE]
48 Load in sysctl settings from the file specified or
49 /etc/sysctl.conf if none given. Specifying - as filename means
50 reading data from standard input. Using this option will mean
51 arguments to sysctl are files, which are read in the order they
52 are specified. The file argument may be specified as regular
53 expression.
54 -a, --all
56 Display all values currently available.
57 --deprecated
59 Include deprecated parameters to --all values listing.
60 -b, --binary
62 Print value without new line.
63 --system
65 Load settings from all system configuration files. Files are
66 read from directories in the following list in given order from
67 top to bottom. Once a file of a given filename is loaded, any
68 file of the same name in subsequent directories is ignored.
69 /run/sysctl.d/*.conf
70 /etc/sysctl.d/*.conf
71 /usr/local/lib/sysctl.d/*.conf
72 /usr/lib/sysctl.d/*.conf
73 /lib/sysctl.d/*.conf
74 /etc/sysctl.conf
75 -r, --pattern pattern
77 Only apply settings that match pattern. The pattern uses
78 extended regular expression syntax.
79 -A Alias of -a
81 -d Alias of -h
83 -f Alias of -p
85 -X Alias of -a
87 -o Does nothing, exists for BSD compatibility.
89 -x Does nothing, exists for BSD compatibility.
91 -h, --help
93 Display help text and exit.
94 -V, --version
96 Display version information and exit.
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99 /sbin/sysctl -a
100 /sbin/sysctl -n kernel.hostname
101 /sbin/sysctl -w kernel.domainname="example.com"
102 /sbin/sysctl -p/etc/sysctl.conf
103 /sbin/sysctl -a --pattern forward
104 /sbin/sysctl -a --pattern forward$
105 /sbin/sysctl -a --pattern 'net.ipv4.conf.(eth|wlan)0.arp'
106 /sbin/sysctl --system --pattern '^net.ipv6'
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109 The base_reachable_time and retrans_time are deprecated. The sysctl
110 command does not allow changing values of these parameters. Users who
111 insist to use deprecated kernel interfaces should push values to /proc
112 file system by other means. For example:
113 echo 256 > /proc/sys/net/ipv6/neigh/eth0/base_reachable_time
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117 /proc/sys
118 /etc/sysctl.conf
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121 sysctl.conf(5) regex(7)
122
124 George Staikos ⟨staikos@0wned.org⟩
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127 Please send bug reports to ⟨procps@freelists.org⟩
128procps-ng Jan 2012 SYSCTL(8)