$ curl cheat.sh/
 cheat.sheets:sysctl 
# List all kernel keys (parameters) and their values.
sysctl [--all|-a]
# As above, but show only specified keys and their values.
sysctl [KEY_1 [KEY_2] ...]

# As above, but instead output only the values.
sysctl [--values|-n] [KEY_1 [KEY_2] ...]
# Not nearly as useful, but alternatively, output only the key names.
sysctl [--names|-N] [KEY_1 [KEY_2] ...]

# Assign one or more kernel keys a new value; usually requires root access.
sysctl [KEY_1=VALUE_1 [KEY_2=VALUE_2] ...]

 tldr:sysctl 
# sysctl
# List and change kernel runtime variables.
# More information: <https://manned.org/sysctl.8>.

# Show all available variables and their values:
sysctl -a

# Set a changeable kernel state variable:
sysctl -w section.tunable=value

# Get currently open file handlers:
sysctl fs.file-nr

# Get limit for simultaneous open files:
sysctl fs.file-max

# Apply changes from `/etc/sysctl.conf`:
sysctl -p

$
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