The sysctl utility retrieves kernel state and allows processes with ap-
propriate privilege to set kernel state. The state to be retrieved or
set is described using a ``Management Information Base'' (``MIB'') style
name, described as a dotted set of components. The -a flag can be used
to list all the currently available string or integer values. The -A
flag will list all the known MIB names including tables. Those with
string or integer values will be printed as with the -a flag; for the
table values, the name of the utility to retrieve them is given.
The -n flag specifies that the printing of the field name should be sup-
pressed and that only its value should be output. This flag is useful
for setting shell variables. For example, to save the pagesize in vari-
able psize, use:
set psize=`sysctl -n hw.pagesize`
If just a MIB style name is given, the corresponding value is retrieved.
If a value is to be set, the -w flag must be specified and the MIB name
followed by an equal sign and the new value to be used.
The information available from sysctl consists of integers, strings, and
tables. The tabular information can only be retrieved by special purpose
programs such as ps, systat, and netstat. The string and integer informa-
tion is summaried below. For a detailed description of these variable
see sysctl(3). The changeable column indicates whether a process with
appropriate privilege can change the value.
