The following commands are available when this module is loaded:
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SPDX-License-Identifier: Apache-2.0
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
Usage: -entropy-available [OPTION]...
Determines if enough entropy bits are available perform a non-blocking read from /dev/random. Exit code 1 indicates entropy pool is not sufficiently filled.
Options:
--help
Prints this help.
--tracecmd
Enables bash debug mode (set -x).
--selftest
Performs a self-test.
--
Terminates the option list.
Examples:
$ -entropy-available
/proc/sys/kernel/random/entropy_avail: 64
/proc/sys/kernel/random/read_wakeup_threshold: 2429
Implementation:
if [[ ! -e /proc/sys/kernel/random/read_wakeup_threshold ]]; then
echo "-entropy-available: Warning: Kernel parameter /proc/sys/kernel/random/read_wakeup_threshold is not present, assuming sufficient entropy is available."
return 0
fi
local avail=$(cat /proc/sys/kernel/random/entropy_avail)
local required=$(cat /proc/sys/kernel/random/read_wakeup_threshold)
echo "/proc/sys/kernel/random/entropy_avail: $avail"
echo "/proc/sys/kernel/random/read_wakeup_threshold: $required"
(( avail > required ))Usage: -fill-entropy [OPTION]... [DURATION]
Fills /dev/random with pseudo-random values from /dev/urandom.
Requirements:
+ Command 'rngd' must be available.
+ Sudo 'rngd' is required.
Parameters:
DURATION (default: '1', integer: 1-?)
Number of seconds the entropy pool will be filled.
Options:
--help
Prints this help.
--tracecmd
Enables bash debug mode (set -x).
--selftest
Performs a self-test.
--
Terminates the option list.
Examples:
$ -fill-entropy
Available entropy bits before: 1000
Generating for 1 second(s)...
Available entropy bits after: 1013
$ -fill-entropy 2
Available entropy bits before: 1013
Generating for 2 second(s)...
Available entropy bits after: 1039
Implementation:
echo -n "Available entropy bits before: "
cat /proc/sys/kernel/random/entropy_avail
echo "Generating for ${_DURATION} seconds..."
local timeoutCmd
if hash timeout 2>/dev/null; then
timeoutCmd="timeout"
elif hash gtimeout 2>/dev/null; then
timeoutCmd="gtimeout"
else
timeoutCmd="perl -e 'alarm shift; exec @ARGV'"
fi
if rngd --help | grep -q -- --feed-interval; then
# using timeoutCmd despite "--feed-interval" parameter because rngd in some environments randomly hangs (e.g. github actions with ubuntu 22)
sudo $timeoutCmd $((_DURATION + 1)) rngd --foreground -r /dev/urandom -o /dev/random --feed-interval ${_DURATION}
elif rngd --help | grep -q -- --timeout; then
# using timeoutCmd despite "--timeout" parameter because rngd in some environments randomly hangs (e.g. github actions with ubuntu 22)
sudo $timeoutCmd $((_DURATION + 1)) rngd --foreground -r /dev/urandom -o /dev/random --timeout ${_DURATION}
else
sudo $timeoutCmd ${_DURATION} rngd --foreground -r /dev/urandom -o /dev/random
fi
echo -n "Available entropy bits after: "
cat /proc/sys/kernel/random/entropy_availUsage: -random-number [OPTION]... RANGE
Generates a random number of the given range. The range is inclusive.
Requirements:
* Either:
+ Command 'shuf' must be available.
* Or:
+ Command 'gshuf' must be available.
Parameters:
RANGE (required, pattern: "[1-9][0-9]*-[1-9][0-9]*")
The numeric range LOW-HIGH, e.g. 1-5.
Options:
--help
Prints this help.
--tracecmd
Enables bash debug mode (set -x).
--selftest
Performs a self-test.
--
Terminates the option list.
Examples:
$ -random-number 1-1
1
$ -random-number 1-5
4
$ -random-number 200-299
253
Implementation:
if hash gshuf &>/dev/null; then # MacOS
gshuf -i ${_RANGE} -n 1
else
shuf -i ${_RANGE} -n 1
fiUsage: -random-string [OPTION]... LENGTH [CHARS]
Prints a random string of the given length containing the given characters.
Parameters:
LENGTH (required, integer: 1-?)
Length of the string to generate.
CHARS (default: '[:graph:]')
String to choose random characters from.
Options:
--help
Prints this help.
--tracecmd
Enables bash debug mode (set -x).
--selftest
Performs a self-test.
--
Terminates the option list.
Examples:
$ -random-string 12 0-9
686026902293
$ -random-string 8 a-zA-Z
ECtQptCz
$ -random-string 10 [:alnum:]
w2TZ8fHaRw
$ -random-string 10 [:alnum:][:punct:]
4pH?+40D):
Implementation:
# "2> >(grep -v "write error" >&2)" and "|| true" to mitigate "tr: write error: Broken pipe" on e.g. GitHub Actions
env -i LC_CTYPE=C tr -dc "$_CHARS" </dev/urandom 2> >(grep -v "write error" >&2) | head -c ${_LENGTH} || trueUsage: -test-all-random [OPTION]...
Performs a selftest of all functions of this module by executing each function with option '--selftest'.
Options:
--help
Prints this help.
--tracecmd
Enables bash debug mode (set -x).
--selftest
Performs a self-test.
--
Terminates the option list.
Implementation:
if [ -e /proc/sys/kernel/random/entropy_avail ]; then -entropy-available --selftest && echo || return 1; fi
if [ -e /proc/sys/kernel/random/entropy_avail ]; then -fill-entropy --selftest && echo || return 1; fi
-random-number --selftest && echo || return 1
if ! [[ $OSTYPE == 'darwin'* && $GITHUB_ACTIONS == 'true' ]]; then -random-string --selftest && echo || return 1; fi